docs: preserve established image semantics in redraw plan

WIP: preserve image redraw experiment and recovery plan
sixel: preserve image aspect across client geometries
2026-09-16 10:11:57 +00:00 · 2026-08-20 12:25:43 +01:00 · 2026-08-19 15:46:09 +01:00 · 2026-08-18 22:57:27 +01:00 · 2026-08-18 12:03:19 +01:00 · 2026-08-17 21:47:49 +01:00
29 changed files with 6071 additions and 703 deletions
--- a/IMAGE-REDRAW-PLAN.md
+++ b/IMAGE-REDRAW-PLAN.md
@@ -0,0 +1,715 @@
+# Image Redraw and Damage Plan
+
+## Purpose
+
+Make image redraws correct and efficient for tiled panes, floating panes,
+scrolling, copy-mode selection, pane borders, pane status lines, scrollbars,
+and clients using different output protocols.
+
+The intended model is retained: the visible screen is a scene of horizontal
+cell spans. A change damages cell-aligned regions, and the compositor redraws
+only scene spans intersecting those regions.
+
+Synchronized output may hide unavoidable intermediate terminal updates, but
+it must not be required for correctness.
+
+## Current state and recovery point
+
+The last clean, pushed commit on `4902-image-support` is:
+
+```
+ec9859b1 sixel: preserve image aspect across client geometries
+```
+
+That commit already contains the important persistent model:
+
+- sparse image placements represented by spans attached to grid lines;
+- input-protocol semantics and placement ordering;
+- source coordinates for cropping placement spans;
+- movement, copying, duplication, and removal of image spans with grid data;
+- per-client output backends for Kitty, SIXEL, and fallback rendering; and
+- cached image/rendering data.
+
+The current uncommitted changes touch eight files and mix several attempted
+optimizations. They are known to damage SIXEL in Mintty and cause unnecessary
+redraws with floating panes. Do not commit them as the solution.
+
+Before discarding them, save one patch outside the branch for reference:
+
+```
+git diff -- image.c regress/image-support.sh screen-redraw.c screen-write.c \
+    server-client.c tmux.h tty.c window-copy.c \
+    > /tmp/4902-image-redraw-experiment.patch
+```
+
+Then restore those tracked files to `ec9859b1` before beginning the new work.
+Do this only after the user explicitly approves the rollback.
+
+### Ideas worth retaining, but reimplementing separately
+
+- Redraw damage should be restricted to scene-visible spans.
+- Image-related selection tests are useful.
+- Floating-pane and pane-status regression scenarios are useful.
+- Window chrome must be emitted after pane image/text composition whenever
+  the same damaged region contains both.
+- A placement's complete canvas may need to be represented even where its
+  pixels are transparent; visibility and alpha must then be tested while
+  compositing rather than by losing the placement geometry.
+- Native scrolling should be selected according to the affected region and
+  backend behaviour.
+
+### Changes not worth retaining in their present form
+
+- Promoting an obscured-pane update to `PANE_REDRAW` and then sometimes to
+  `CLIENT_REDRAWWINDOW`.
+- Repairing images directly from individual `tty_cmd_*` text functions.
+- Separate ad-hoc redraw paths for images, selection, scrollbars, borders,
+  and floating panes.
+- The current `TTY_CTX_IMAGE_SCROLL`, `TTY_CTX_PANE_FULL_WIDTH`, and
+  `CLIENT_REDRAWSCROLLBARS` plumbing as a combined patch.
+- Assuming an unchanged pane-status string does not need physical redraw
+  after some other drawing operation has covered its cells.
+
+## Required invariants
+
+These rules should be written down in code comments and enforced throughout
+the implementation.
+
+1. **Input determines semantics.** Whether text removes an image layer, lies
+   above it, or lies below it is determined by the protocol received from the
+   application. It must not depend on whether the outer client uses Kitty,
+   SIXEL, or fallback output.
+
+2. **Output backends encode a scene.** An output backend may choose different
+   escape sequences, caches, or cropping, but it must render the same logical
+   result.
+
+3. **One compositor owns repair.** No output path may independently erase and
+   reconstruct image cells without going through the same scene ordering.
+
+4. **Damage is regional.** Ordinary content changes do not become pane-wide
+   or window-wide redraws. Full redraw remains appropriate for attachment,
+   resize, geometry changes, terminal reset, or invalid scene geometry.
+
+5. **Damage uses cell coordinates.** Pixel offsets are handled when an image
+   backend maps the damaged cells to a source-pixel crop.
+
+6. **Logical state changes before physical output.** Grid text and image spans
+   are moved, removed, or inserted first. Rendering then reads the completed
+   logical state.
+
+7. **Chrome is part of composition.** Pane borders, pane status lines,
+   scrollbars, menus, and floating panes must not be repaired independently in
+   an order that allows image output to cover them afterward.
+
+8. **No-image behaviour remains unchanged.** When a damaged region does not
+   intersect image data or graphical overlays, existing fast text output and
+   native scrolling should remain available.
+
+## Established image semantics
+
+The image semantics present at the `ec9859b1` recovery point are a
+compatibility requirement. They resulted from the review discussion in PR
+#5445, particularly the temporal-versus-positional model described in
+[Theory and Practice of Sprixels](https://nick-black.com/dankwiki/index.php?title=Theory_and_Practice_of_Sprixels#Transparency_and_z-ordering),
+and were accepted after commit `a4abd616`, which added the corresponding
+manual visual checks.
+
+- SIXEL input is temporal. Transparent pixels preserve what existed when the
+  SIXEL was emitted. A later text write annihilates the affected SIXEL cells;
+  the SIXEL does not remain logically behind that text.
+- Kitty input is positional. Negative-z placements remain below the text plane;
+  nonnegative placements remain above it. Text writes do not convert or remove
+  Kitty placements merely because the output client uses SIXEL.
+- Overlapping placements remain separate ordered layers. Transparent pixels in
+  an upper placement reveal retained lower placements or text.
+- Input protocol, z-index, and placement order determine the logical scene. The
+  attached client's output protocol only determines how that scene is encoded.
+- Redraw, damage, scrolling, copy mode, and backend conversion must preserve
+  these rules exactly.
+
+The manual checks introduced by `a4abd616` and the corresponding regression
+cases are semantic compatibility tests, not merely visual diagnostics.
+
+## Coordinate spaces
+
+Keep conversions explicit. Do not pass ambiguous `x` and `y` values between
+layers.
+
+- **Grid coordinates:** include history and belong to a pane's `struct grid`.
+- **Pane coordinates:** visible cells inside a pane.
+- **Window coordinates:** include pane offsets and floating-pane positions.
+- **Client scene coordinates:** window coordinates clipped by the client's
+  viewport (`ox`, `oy`, `sx`, and `sy`).
+- **Terminal coordinates:** include the client status-line offset and any
+  terminal viewport offset.
+- **Image source coordinates:** identify cell rows/columns within a placement;
+  the backend maps these to source pixels using terminal cell geometry and
+  placement pixel offsets.
+
+Store damage in window coordinates. Translate and clip it separately for each
+client when drawing, because clients may have different viewports, status-line
+positions, cell geometries, and output backends.
+
+## Compartmentalization
+
+Keep image implementation details in the existing image files. The rest of
+tmux should know only that some scene cells require image-aware composition.
+
+### `image.c`
+
+Own all protocol-independent image state and composition policy:
+
+- placements, spans, input protocol, z-index, serial ordering, and alpha;
+- applying input semantics when text overwrites image cells;
+- testing whether a grid rectangle intersects image placements;
+- mapping a damaged cell rectangle to ordered image fragments;
+- deciding which logical image layers are below or above the text plane;
+- generic backend dispatch; and
+- public image helpers used by the redraw subsystem.
+
+### `image-sixel.c`
+
+Own only SIXEL-specific output details:
+
+- cached quantized/indexed representations;
+- mapping cell crops to pixel and six-pixel-band crops;
+- emitting SIXEL fragments;
+- alpha and palette encoding; and
+- backend-specific reset, erase, and scrolling capabilities.
+
+### `image-kitty.c`
+
+Own only Kitty-specific output details:
+
+- client-side transmission and placement caches;
+- placement creation, clipping, movement, and deletion;
+- Kitty IDs and geometry; and
+- backend-specific reset and scrolling behaviour.
+
+### Other tmux files
+
+- `screen-redraw.c` owns scene construction, damage clipping, and the ordering
+  of pane content versus window chrome. It calls generic `image.c` helpers and
+  contains no Kitty or SIXEL protocol logic.
+- `screen-write.c` updates logical grid state and reports pane/window damage.
+  It must not render image fragments or select an output backend.
+- `tty.c` owns terminal text and scrolling primitives. It receives an already
+  selected native-scroll operation; it must not reconstruct image layers or
+  call image repair after individual characters.
+- `server-client.c` schedules and drains per-client damage. It must not inspect
+  image placements or output protocols.
+- `window-copy.c` reports copy-mode damage and copies logical image state using
+  generic image helpers; it must not render images itself.
+- `tmux.h` exposes only the minimum generic structures and function prototypes
+  required across those boundaries.
+
+Prefer one generic call from `screen-redraw.c` into `image.c` over `ENABLE_IMAGES`
+branches scattered through tty commands. A build without image support should
+retain the existing redraw path with minimal conditional code.
+
+## Damage representation
+
+Add a small regional damage abstraction owned by the redraw subsystem. Do not
+add per-cell queues or enlarge `struct grid_cell`.
+
+A damage entry needs:
+
+```
+x, y, sx, sy       window-cell rectangle
+reason             content, scroll exposure, pane move, chrome, and so on
+```
+
+The exact names should follow tmux style. A short list or dynamic array per
+client is sufficient. When a new rectangle is added:
+
+- clip it to the window;
+- discard empty rectangles;
+- merge overlapping or directly adjacent rectangles where that does not make
+  the result substantially larger;
+- cap the list at a modest number; above the cap, replace it with their union;
+- promote to a full redraw only if geometry is invalid or the union covers
+  most of the client scene.
+
+A shared window damage list must not be cleared after the first client draws.
+Either append translated window rectangles to every affected client, or give
+damage events monotonically increasing sequence numbers so each client can
+consume them independently. The simpler initial implementation is to append
+window-coordinate rectangles to each client currently displaying the window.
+
+Suggested public operations are conceptually:
+
+```
+redraw_damage_window(window, x, y, sx, sy, reason)
+redraw_damage_pane(window_pane, x, y, sx, sy, reason)
+redraw_damage_client(client, x, y, sx, sy, reason)
+```
+
+Do not expose image-backend details through these calls.
+
+## Regional scene composition
+
+Extend `screen-redraw.c` so an existing `redraw_scene` can be drawn through a
+set of clipping rectangles.
+
+For every damaged line:
+
+1. Intersect the damage rectangle with that line's scene spans.
+2. Split only at damage boundaries; do not rebuild the complete scene.
+3. Draw intersecting pane content in logical layer order.
+4. Draw window chrome intersecting the same rectangle last.
+
+For a pane span, the scene has already selected the topmost visible pane at
+that position. Composition inside that pane should then be explicit:
+
+1. image placements below the text plane, such as negative Kitty z-indexes;
+2. the text plane, including the requested copy-mode style;
+3. surviving temporal SIXEL placements and images above the text plane;
+4. pane borders, pane status, scrollbars, menus, and other chrome.
+
+The exact placement order is already represented by `struct image_placement`
+and its input protocol, z-index, and serial. Do not derive it from the client's
+output backend.
+
+Only the topmost pane content is normally needed because panes are opaque.
+Underlying pane content is retained in its own grid and becomes visible when a
+floating pane moves, at which time the old floating-pane rectangle is damaged
+and recomposed.
+
+### Image fragments
+
+An `image_span` is placement metadata, not a separately stored bitmap. For an
+intersection, compute the corresponding source-cell rectangle and ask the
+backend to emit that crop from its cached rendering.
+
+- Do not rerun quantization or dithering for every small damage rectangle.
+- SIXEL output operates in six-pixel vertical bands. Expand or clip the
+  backend operation as required, then ensure any additionally touched cells
+  are included in the same composition pass.
+- A transparent top image requires lower image layers to be drawn first.
+- Kitty placements may be deleted, clipped, or replaced only within the
+  damaged placement region.
+
+## Fast text writes
+
+Do not route every ordinary character through a deferred full compositor.
+
+For an application text write:
+
+1. Apply input-protocol damage rules to the logical image spans. For example,
+   text written after a SIXEL image removes the affected SIXEL coverage.
+2. Test whether the affected cells still intersect any image layer or scene
+   overlay requiring composition.
+3. If not, retain the existing direct `tty_cmd_cell`/`tty_cmd_cells` path.
+4. If they do, suppress conflicting direct terminal repair and enqueue only
+   those cells for regional composition.
+
+This decision belongs above the backend-specific tty output functions. Avoid
+callbacks such as `image_draw_after_text()` from several `tty_cmd_*` functions;
+they reproduce ordering logic in multiple places.
+
+## Selection and copy mode
+
+Copy mode must not mutate the application's logical image placements.
+
+- Treat selection as a temporary tmux UI style on the text plane.
+- Follow the chosen policy that selection highlighting does not overwrite
+  image-covered cells.
+- Mouse motion should damage only cells whose selection state actually
+  changed.
+- If changed selection cells do not intersect visible images, draw them using
+  the normal text fast path.
+- If they intersect an image canvas, compose those cells once; do not erase a
+  whole image or pane.
+- Entering or leaving copy mode should damage the visible pane rectangle once,
+  not repeatedly for every unchanged mouse event.
+
+Copy-mode image spans should be copied before its text view is composed, but
+this should be implemented through the same logical state and damage API, not
+through special tty repair calls.
+
+## Floating panes
+
+### Focus changes
+
+Changing the active pane should damage only cells whose appearance changes:
+
+- affected pane borders;
+- pane status cells whose style or contents change; and
+- any active-pane indicators.
+
+It must not redraw pane interiors or retransmit unrelated SIXEL images.
+
+### Moving or resizing a floating pane
+
+For an old rectangle `A` and new rectangle `B`:
+
+- invalidate the scene geometry;
+- damage `A union B` (represented as a few rectangles rather than necessarily
+  one large bounding box);
+- rebuild the scene because pane ownership changed;
+- recompose only spans intersecting those rectangles.
+
+The old rectangle restores tiled panes and any image fragments that were
+previously hidden. The new rectangle draws the floating pane and its chrome.
+Multiple overlapping floating panes follow their window z-order.
+
+## Scrolling
+
+Implement scrolling in three stages. Do not begin with the most complicated
+native-scroll optimization.
+
+### Stage 1: correct regional redraw
+
+1. Move grid text and image spans using the existing grid operations.
+2. Record the pane scroll rectangle and newly exposed rows.
+3. Recompose that rectangle from the completed logical scene.
+
+This may still retransmit more image data than desired, but it establishes a
+correct regional baseline without pane- or window-wide redraws.
+
+### Stage 2: native scrolling without obstructions
+
+Use the terminal's native scroll operation only when:
+
+- the backend/terminal is known to scroll its image pixels consistently;
+- the source and destination rectangle belong to the same visible pane;
+- no floating pane, menu, overlay, pane border/status, or reserved scrollbar
+  intersects it;
+- required vertical and horizontal margins are available and reliable; and
+- existing BCE and terminal-size checks permit the operation.
+
+After native scrolling, compose only newly exposed rows and any protocol-sized
+boundary expansion.
+
+### Stage 3: mixed native scrolling around obstructions
+
+Derive safe rectangles from visible scene spans:
+
+- a destination cell is native-scrollable only when its source cell and
+  destination cell are both visible parts of the same pane;
+- coalesce equal horizontal ranges across adjacent rows into rectangles;
+- native-scroll those maximal rectangles;
+- recompose cells crossing an obstruction boundary and newly exposed cells.
+
+With one floating pane, left and right strips can often scroll over the full
+height. Above and below it, cells whose source crosses behind the floating pane
+must be recomposed rather than recovered from terminal pixels.
+
+As a simpler optional strategy, native-scroll the full tiled-pane rectangle
+and recompose the floating pane's old/current rectangles afterward. This is
+correct if all disturbed cells are marked, but may visibly flash without
+synchronized output. Prefer safe-rectangle scrolling once correctness is
+established.
+
+If rectangle decomposition becomes too fragmented, fall back to regional
+composition. It is an optimization, never a separate correctness path.
+
+## Redraw scheduling
+
+Do not turn queued regional damage into `CLIENT_REDRAWWINDOW` merely because
+the tty output buffer is nonempty. Preserve the damage list and process it
+after output drains.
+
+Use full redraw only for:
+
+- initial attachment;
+- client or terminal geometry changes;
+- a terminal reset or invalid backend cache;
+- layout/viewport changes where rebuilding and clipping regions is not yet
+  safe; or
+- a damage union large enough that full redraw is cheaper.
+
+Focus changes, selection changes, ordinary scrolling, and moving one floating
+pane should remain regional.
+
+## Debugging instrumentation
+
+Add temporary debug logging before optimizing:
+
+- damage reason and window rectangle;
+- client clipping and coordinate translation;
+- scene generation used;
+- native-scroll rectangles selected;
+- spans recomposed in each layer phase; and
+- image fragments emitted by each backend.
+
+The log should make it possible to answer, for every SIXEL retransmission,
+which damage rectangle required it. Remove excessively noisy instrumentation
+before the final commit or keep it behind normal verbose logging.
+
+## Tests
+
+Build the tests before each optimization and keep each test focused on one
+invariant.
+
+### Automated regressions
+
+1. **No-image baseline:** ordinary output, scrolling, copy mode, floating pane
+   focus, borders, status lines, and scrollbars behave unchanged.
+2. **Focus only:** changing focus with a SIXEL elsewhere emits no SIXEL DCS and
+   updates only the affected border/status cells.
+3. **Selection outside image:** emits no image output.
+4. **Selection crossing image:** the image remains intact during and after the
+   drag; only changed non-image cells are highlighted.
+5. **Unobstructed scroll:** logical image spans move with text; where native
+   scrolling is supported, no complete SIXEL retransmission occurs.
+6. **Scroll with floating pane:** both pane-status lines, borders, scrollbar,
+   floating-pane contents, and visible image fragments remain correct.
+7. **Move floating pane:** old and new rectangles are restored; unrelated image
+   regions are not emitted.
+8. **Multiple floating panes:** overlapping z-order remains correct while the
+   top pane moves.
+9. **Transparent placement:** lower images/text show through correctly, and
+   moving/selection does not treat transparency as absent placement geometry.
+10. **Cross-backend clients:** the same input scene produces equivalent results
+    on Kitty, SIXEL, and fallback clients attached simultaneously.
+11. **Pane status top/bottom:** unchanged status contents are physically
+    restored if their cells were damaged.
+12. **Scrollbar reserved/overlay:** scroll thumb and track remain present and
+    images do not overwrite them.
+
+Where possible, capture raw terminal output and assert both presence and
+absence of DCS/APC sequences. `capture-pane` alone cannot prove physical output
+ordering because it observes logical grid contents rather than terminal image
+pixels.
+
+### Manual matrix
+
+Test at least:
+
+- Microsoft Terminal with SIXEL;
+- Mintty with SIXEL;
+- WezTerm with SIXEL;
+- Kitty with Kitty output;
+- a Kitty client attached to a session created from a SIXEL client and the
+  reverse; and
+- a terminal without graphical image support.
+
+For each, test scrolling by application output and mouse wheel, selecting text,
+entering/leaving copy mode, changing focus, opening/closing/moving a floating
+pane, pane status at top and bottom, and scrollbars.
+
+## Implementation steps and commit boundaries
+
+This must not be implemented as one monolithic change. Each numbered step is a
+separate commit, review, and testing gate. Do not begin the next step until the
+current step passes its focused tests. If a step exposes a pre-existing bug,
+record it before expanding the patch.
+
+### Step 0: archive the experiment and recover the baseline
+
+**Goal:** Begin development from known source rather than repairing the mixed
+experimental diff.
+
+**Work:**
+
+- Preserve the current diff and this plan on a clearly named WIP branch.
+- Return `4902-image-support` to clean commit `ec9859b1`.
+- Build with and without image support.
+- Run the existing image regression and ordinary tmux regression suite.
+
+**Gate:** The branch is clean and existing behaviour is reproduced. No product
+code is changed in this step.
+
+### Step 1: add focused regressions and tracing
+
+**Goal:** Establish observable failures before changing redraw behaviour.
+
+**Primary files:** `regress/image-support.sh`, temporary debug logging in
+`screen-redraw.c` if necessary.
+
+**Work:** Add independent tests for focus-only changes, selection crossing an
+image, unobstructed scrolling, scrolling beneath a floating pane, moving a
+floating pane, both pane-status lines, and scrollbars. Raw terminal output must
+be used where a test needs to prove that SIXEL or Kitty data was or was not
+emitted.
+
+**Gate:** Each test either passes on the baseline or has a documented expected
+failure. Tests must not depend on timing races or visual screenshots. The
+existing edge-case checks introduced by `a4abd616` must pass unchanged on the
+recovery baseline and establish the semantic compatibility result expected by
+later gates.
+
+**Not included:** No redraw implementation changes.
+
+### Step 2: introduce regional damage scheduling
+
+**Goal:** Represent and preserve small window-coordinate damage rectangles
+without changing the rendered result.
+
+**Primary files:** `screen-redraw.c`, `server-client.c`, minimal declarations in
+`tmux.h`.
+
+**Work:** Add per-client damage storage, clipping, merging, a complexity cap,
+and verbose logging. Existing callers may initially convert the damage to the
+same redraw they used before. Pending tty output must retain the region rather
+than promote it automatically to a full-window redraw.
+
+**Gate:** No-image and image output remain visually and byte-for-byte equivalent
+where practical. Unit-style tests verify rectangle clipping and merging.
+
+**Not included:** No image-layer traversal, selection changes, floating-pane
+optimization, or native scrolling.
+
+### Step 3: add a generic image-region composition API
+
+**Goal:** Give the scene compositor one protocol-independent way to render the
+image layers intersecting a cell rectangle.
+
+**Primary files:** `image.c`, `image-sixel.c`, `image-kitty.c`, with only generic
+prototypes in `tmux.h`.
+
+**Work:**
+
+- In `image.c`, intersect damage with placement spans and preserve logical
+  input/z/serial order.
+- In `image-sixel.c`, emit a crop from cached quantized data and handle SIXEL
+  band alignment.
+- In `image-kitty.c`, update/delete/place only the intersecting cached
+  placements.
+- Define clearly separate below-text and above-text passes.
+
+**Gate:** Rendering a whole image as adjacent damaged rectangles produces the
+same final scene as rendering it in one operation. Test transparent and
+overlapping placements on both output backends. The `a4abd616` semantic
+compatibility checks must continue to pass unchanged.
+
+**Not included:** No changes to individual tty text commands and no native
+scroll optimization.
+
+### Step 4: clip scene composition to damage rectangles
+
+**Goal:** Make `screen-redraw.c` repaint only scene spans intersecting queued
+damage.
+
+**Primary files:** `screen-redraw.c`; generic calls into `image.c`.
+
+**Work:** For each damaged line, intersect existing redraw spans, compose the
+selected pane's below-text images, text, and above-text images, then draw
+intersecting chrome last. Full redraw continues to use the same compositor with
+a full-client damage rectangle.
+
+**Gate:** Full and tiled panes redraw correctly; pane borders, pane status,
+scrollbars, menus, and images have deterministic output order. No floating-pane
+movement or scroll optimization is added yet.
+
+### Step 5: route text and selection damage through the compositor
+
+**Goal:** Repair only cells where text or copy-mode selection interacts with
+image layers.
+
+**Primary files:** `screen-write.c`, `window-copy.c`, `screen-redraw.c`, and
+logical helpers in `image.c`.
+
+**Work:** Apply input semantics to logical spans first. Preserve direct tty text
+output when no image placement intersects the cells. Otherwise enqueue those
+cells for composition. Selection changes damage only cells whose selection
+state changed and follow the policy of not overwriting image-covered cells.
+
+**Gate:** Dragging selection across an image never damages it, entering/leaving
+copy mode restores the same scene, and selection outside images emits no image
+data. The `a4abd616` semantic compatibility checks must continue to pass
+unchanged.
+
+**Not included:** Do not add image callbacks to `tty_cmd_cell`,
+`tty_cmd_cells`, or `tty_cmd_clearcharacter`.
+
+### Step 6: make floating-pane changes regional
+
+**Goal:** Focus, movement, resize, open, and close operations damage only the
+cells whose scene ownership or chrome changed.
+
+**Primary files:** floating-pane/window code that reports geometry changes,
+plus `screen-redraw.c`. Image implementation remains in the image files.
+
+**Work:** Focus changes enqueue border/status cells only. Movement and resize
+enqueue the old and new pane rectangles and invalidate scene geometry. Regional
+composition restores underlying panes/images in the old rectangle and draws
+the floating pane in the new rectangle.
+
+**Gate:** Changing focus emits no unrelated SIXEL/APC. Moving a floating pane
+does not damage images, either pane-status line, borders, or scrollbars. Test
+one and multiple overlapping floating panes.
+
+### Step 7: implement correct regional scrolling without native optimization
+
+**Goal:** Establish correct scrolling using logical state plus regional
+composition.
+
+**Primary files:** grid/image state helpers in `image.c`, damage reporting in
+`screen-write.c`, composition in `screen-redraw.c`.
+
+**Work:** Move text and image spans first, then damage the scroll rectangle and
+compose it. Do not use special image repair from `tty.c`.
+
+**Gate:** Application scrolling, mouse-wheel copy-mode scrolling, partial
+scroll regions, scrollbars, and scrolling beneath floating panes are correct on
+Kitty, Microsoft Terminal, Mintty, and WezTerm. This step may redraw more than
+the final optimized version, but must not redraw outside the scroll rectangle.
+The `a4abd616` semantic compatibility checks must continue to pass unchanged.
+
+### Step 8: enable native scrolling for unobstructed rectangles
+
+**Goal:** Avoid retransmitting image pixels when the terminal can safely move
+them.
+
+**Primary files:** scroll planning in `screen-redraw.c`, generic backend
+capability in `image.c`, backend facts in `image-sixel.c` and `image-kitty.c`,
+terminal primitive execution in `tty.c`.
+
+**Work:** Select native scrolling only when source/destination cells belong to
+the same unobstructed pane and terminal margins/backend behaviour permit it.
+Compose newly exposed rows afterward. Retain Step 7 as the fallback.
+
+**Gate:** Raw output proves the native scroll is used and a complete image is
+not retransmitted. Final output must match Step 7 on every tested backend.
+
+### Step 9: decompose scrolling around floating panes
+
+**Goal:** Combine native scrolling of safe rectangles with composition of
+obstructed and boundary rectangles.
+
+**Primary files:** scroll planning and scene-span traversal in
+`screen-redraw.c`; no new protocol logic outside the image files.
+
+**Work:** Derive maximal rectangles where both source and destination are
+visible cells of the same pane, coalesce adjacent equal ranges, natively scroll
+them, and compose everything else. Enforce a fragmentation threshold that
+falls back to Step 7.
+
+**Gate:** Scrolling beneath one or several floating panes produces the same
+final scene as Step 7, reduces emitted image data, and never loses pane status,
+borders, scrollbars, or images.
+
+### Step 10: cleanup, performance checks, and full regression
+
+**Goal:** Remove superseded paths only after all replacements are proven.
+
+**Work:** Remove obsolete redraw helpers and flags introduced or made unused by
+the new path. Reduce temporary logging. Check memory growth, rectangle-list
+bounds, output byte counts, and behaviour without image support. Run the entire
+regression suite and the manual terminal matrix.
+
+**Gate:** All completion criteria below are satisfied. Synchronized output may
+improve appearance, but disabling it does not alter final contents. The
+`a4abd616` semantic compatibility checks must continue to pass unchanged.
+
+Do not squash these implementation steps during development. Keeping their
+boundaries visible makes it possible to bisect correctness and performance
+regressions. They can be reorganized later only after review.
+
+## Completion criteria
+
+The work is complete when:
+
+- Mintty, Microsoft Terminal, WezTerm, and Kitty show no persistent damage;
+- focus and selection do not retransmit unrelated images;
+- floating-pane movement redraws only old/new affected regions;
+- scrolling preserves images, pane borders, both tiled and floating pane
+  status lines, and scrollbars;
+- input semantics produce the same composition on every output backend;
+- no-image performance and behaviour remain unchanged;
+- full regression tests pass; and
+- synchronized output improves appearance but disabling it never changes the
+  final screen contents.
--- a/Makefile.am
+++ b/Makefile.am
@@ -5,7 +5,8 @@ CLEANFILES = tmux.1.mdoc tmux.1.man cmd-parse.c
 # Distribution tarball options.
 EXTRA_DIST = \
 	CHANGES README COPYING example_tmux.conf \
-	osdep-*.c mdoc2man.awk tmux.1
+	osdep-*.c mdoc2man.awk tmux.1 \
+	tools/generate-image-diacritics.sh
 dist_EXTRA_tmux_SOURCES = compat/*.[ch]

 # Preprocessor flags.
@@ -246,9 +247,9 @@ if HAVE_UTF8PROC
 nodist_tmux_SOURCES += compat/utf8proc.c
 endif

-# Enable sixel support.
-if ENABLE_SIXEL
-dist_tmux_SOURCES += image.c image-sixel.c
+# Enable image support.
+if ENABLE_IMAGES
+dist_tmux_SOURCES += image.c image-sixel.c image-kitty.c
 endif

 # Add bits for fuzzing if enabled.
--- a/configure.ac
+++ b/configure.ac
@@ -530,15 +530,34 @@ if test "x$enable_cgroups" = xyes; then
 	fi
 fi

-# Enable sixel support.
+# Enable image support.
+AC_ARG_ENABLE(
+	images,
+	AS_HELP_STRING(--enable-images, enable Kitty/SIXEL/ASCII images)
+)
+
+# Keep the old option as an alias for one compatibility cycle.
 AC_ARG_ENABLE(
 	sixel,
-	AS_HELP_STRING(--enable-sixel, enable sixel images)
+	AS_HELP_STRING(--enable-sixel, deprecated alias for --enable-images)
 )
 if test "x$enable_sixel" = xyes; then
-	AC_DEFINE(ENABLE_SIXEL)
+	enable_images=yes
 fi
-AM_CONDITIONAL(ENABLE_SIXEL, [test "x$enable_sixel" = xyes])
+if test "x$enable_images" = xyes; then
+	PKG_CHECK_MODULES(
+		IMAGE,
+		[libpng >= 1.6 zlib],
+		[
+			AM_CPPFLAGS="$IMAGE_CFLAGS $AM_CPPFLAGS"
+			CPPFLAGS="$AM_CPPFLAGS $SAVED_CPPFLAGS"
+			LIBS="$IMAGE_LIBS $LIBS"
+		],
+		AC_MSG_ERROR("image support requires libpng 1.6 and zlib")
+	)
+	AC_DEFINE(ENABLE_IMAGES)
+fi
+AM_CONDITIONAL(ENABLE_IMAGES, [test "x$enable_images" = xyes])

 # Check for b64_ntop. If we have b64_ntop, we assume b64_pton as well.
 AC_MSG_CHECKING(for b64_ntop)
@@ -1137,10 +1156,10 @@ if test "x$enable_asan" = xyes; then
 else
 	AC_MSG_NOTICE([ASAN: off])
 fi
-if test "x$enable_sixel" = xyes; then
-	AC_MSG_NOTICE([SIXEL: on])
+if test "x$enable_images" = xyes; then
+	AC_MSG_NOTICE([images: on])
 else
-	AC_MSG_NOTICE([SIXEL: off])
+	AC_MSG_NOTICE([images: off])
 fi
 if test "x$enable_debug" = xyes; then
 	AC_MSG_NOTICE([debug: on])
--- a/format.c
+++ b/format.c
@@ -3018,6 +3018,17 @@ format_cb_sixel_support(__unused struct format_tree *ft)
 #endif
 }

+/* Callback for image_support. */
+static void *
+format_cb_image_support(__unused struct format_tree *ft)
+{
+#ifdef ENABLE_IMAGES
+	return (xstrdup("1"));
+#else
+	return (xstrdup("0"));
+#endif
+}
+
 /* Callback for active_window_index. */
 static void *
 format_cb_active_window_index(struct format_tree *ft)
@@ -3681,6 +3692,9 @@ static const struct format_table_entry format_table[] = {
 	{ "host_short", FORMAT_TABLE_STRING,
 	  format_cb_host_short
 	},
+	{ "image_support", FORMAT_TABLE_STRING,
+	  format_cb_image_support
+	},
 	{ "insert_flag", FORMAT_TABLE_STRING,
 	  format_cb_insert_flag
 	},
--- a/grid.c
+++ b/grid.c
@@ -86,6 +86,9 @@ grid_check_is_clear(struct grid *gd)
 		assert(gl->extdsize == 0);
 		assert(gl->flags == 0);
 		assert(gl->time == 0);
+#ifdef ENABLE_IMAGES
+		assert(gl->images == NULL);
+#endif
 	}
 }
 #else
@@ -353,6 +356,9 @@ grid_free_line(struct grid *gd, u_int py)
 	assert(gl->cellsize == 0 || gl->celldata != NULL);
 #endif

+#ifdef ENABLE_IMAGES
+	image_grid_free_line(gd, gl);
+#endif
 	free(gl->celldata);
 	free(gl->extddata);
 	memset(gl, 0, sizeof *gl);
@@ -397,6 +403,9 @@ void
 grid_destroy(struct grid *gd)
 {
 	grid_free_lines(gd, 0, gd->hsize + gd->sy);
+#ifdef ENABLE_IMAGES
+	image_grid_free(gd);
+#endif
 	free(gd->linedata);
 	free(gd);
 }
@@ -729,6 +738,9 @@ grid_clear(struct grid *gd, u_int px, u_int py, u_int nx, u_int ny, u_int bg)

 	if (nx == 0 || ny == 0)
 		return;
+#ifdef ENABLE_IMAGES
+	image_grid_damage(gd, px, py, nx, ny);
+#endif

 	if (px == 0 && nx == gd->sx) {
 		grid_clear_lines(gd, py, ny, bg);
@@ -764,6 +776,10 @@ grid_clear(struct grid *gd, u_int px, u_int py, u_int nx, u_int ny, u_int bg)
 void
 grid_clear_lines(struct grid *gd, u_int py, u_int ny, u_int bg)
 {
+	struct grid_line	*gl;
+#ifdef ENABLE_IMAGES
+	struct image_line	*images;
+#endif
 	u_int	yy;

 	if (ny == 0)
@@ -775,8 +791,18 @@ grid_clear_lines(struct grid *gd, u_int py, u_int ny, u_int bg)
 		return;

 	for (yy = py; yy < py + ny; yy++) {
-		grid_free_line(gd, yy);
+		gl = &gd->linedata[yy];
+#ifdef ENABLE_IMAGES
+		image_grid_damage(gd, 0, yy, gd->sx, 1);
+		images = gl->images;
+#endif
+		free(gl->celldata);
+		free(gl->extddata);
+		memset(gl, 0, sizeof *gl);
 		grid_empty_line(gd, yy, bg);
+#ifdef ENABLE_IMAGES
+		gl->images = images;
+#endif
 	}
 	if (py != 0)
 		gd->linedata[py - 1].flags &= ~GRID_LINE_WRAPPED;
@@ -841,6 +867,9 @@ grid_move_cells(struct grid *gd, u_int dx, u_int px, u_int py, u_int nx,

 	grid_expand_line(gd, py, px + nx, 8);
 	grid_expand_line(gd, py, dx + nx, 8);
+#ifdef ENABLE_IMAGES
+	image_grid_move_cells(gd, dx, px, py, nx);
+#endif
 	memmove(&gl->celldata[dx], &gl->celldata[px],
 	    nx * sizeof *gl->celldata);
 	if (dx + nx > gl->cellused)
@@ -1213,7 +1242,6 @@ grid_string_cells(struct grid *gd, u_int px, u_int py, u_int nx,
 		grid_get_cell(gd, xx, py, &gc);
 		if (gc.flags & GRID_FLAG_PADDING)
 			continue;
-
 		if (lastgc != NULL && (flags & GRID_STRING_WITH_SEQUENCES)) {
 			grid_string_cells_code(*lastgc, &gc, code, sizeof code,
 			    flags, s, &has_link);
@@ -1280,11 +1308,18 @@ grid_duplicate_lines(struct grid *dst, u_int dy, struct grid *src, u_int sy,
 {
 	struct grid_line	*dstl, *srcl;
 	u_int			 yy;
+#ifdef ENABLE_IMAGES
+	u_int			 original_dy, original_sy;
+#endif

 	if (dy + ny > dst->hsize + dst->sy)
 		ny = dst->hsize + dst->sy - dy;
 	if (sy + ny > src->hsize + src->sy)
 		ny = src->hsize + src->sy - sy;
+#ifdef ENABLE_IMAGES
+	original_dy = dy;
+	original_sy = sy;
+#endif
 	grid_free_lines(dst, dy, ny);

 	for (yy = 0; yy < ny; yy++) {
@@ -1292,6 +1327,9 @@ grid_duplicate_lines(struct grid *dst, u_int dy, struct grid *src, u_int sy,
 		dstl = &dst->linedata[dy];

 		memcpy(dstl, srcl, sizeof *dstl);
+#ifdef ENABLE_IMAGES
+		dstl->images = NULL;
+#endif
 		if (srcl->cellsize != 0) {
 			dstl->celldata = xreallocarray(NULL,
 			    srcl->cellsize, sizeof *dstl->celldata);
@@ -1311,6 +1349,9 @@ grid_duplicate_lines(struct grid *dst, u_int dy, struct grid *src, u_int sy,
 		sy++;
 		dy++;
 	}
+#ifdef ENABLE_IMAGES
+	image_grid_duplicate_lines(dst, original_dy, src, original_sy, ny);
+#endif
 }

 /* Mark line as dead. */
@@ -1321,6 +1362,30 @@ grid_reflow_dead(struct grid_line *gl)
 	gl->flags = GRID_LINE_DEAD;
 }

+/* Image rows are cell-aligned and must not be reflowed like text. */
+static int
+grid_reflow_has_image(struct grid_line *gl)
+{
+	struct grid_cell	 gc;
+	u_int			 i;
+
+#ifdef ENABLE_IMAGES
+	if (image_grid_line_has_images(gl))
+		return (1);
+#endif
+	if (~gl->flags & GRID_LINE_EXTENDED)
+		return (0);
+	for (i = 0; i < gl->cellused; i++) {
+		grid_get_cell1(gl, i, &gc);
+		/* Kitty Unicode placeholder base character (U+10EEEE). */
+		if (gc.data.size >= 4 && gc.data.data[0] == 0xf4 &&
+		    gc.data.data[1] == 0x8e && gc.data.data[2] == 0xbb &&
+		    gc.data.data[3] == 0xae)
+			return (1);
+	}
+	return (0);
+}
+
 /* Add lines, return the first new one. */
 static struct grid_line *
 grid_reflow_add(struct grid *gd, u_int n)
@@ -1383,6 +1448,10 @@ grid_reflow_join(struct grid *target, struct grid *gd, u_int sx, u_int yy,
 			break;
 		line = yy + 1 + lines;

+		/* Do not join wrapped text to a cell-aligned image row. */
+		if (grid_reflow_has_image(&gd->linedata[line]))
+			break;
+
 		/* If the next line is empty, skip it. */
 		if (~gd->linedata[line].flags & GRID_LINE_WRAPPED)
 			wrapped = 0;
@@ -1443,8 +1512,7 @@ grid_reflow_join(struct grid *target, struct grid *gd, u_int sx, u_int yy,

 	/* Remove the lines that were completely consumed. */
 	for (i = yy + 1; i < yy + 1 + lines; i++) {
-		free(gd->linedata[i].celldata);
-		free(gd->linedata[i].extddata);
+		grid_free_line(gd, i);
 		grid_reflow_dead(&gd->linedata[i]);
 	}

@@ -1546,6 +1614,12 @@ grid_reflow(struct grid *gd, u_int sx)
 		if (gl->flags & GRID_LINE_DEAD)
 			continue;

+		/* Keep image layers at their original cell coordinates. */
+		if (grid_reflow_has_image(gl)) {
+			grid_reflow_move(target, gl);
+			continue;
+		}
+
 		/*
 		 * Work out the width of this line. at is the point at which
 		 * the available width is hit, and width is the full line
--- a/image-kitty.c
+++ b/image-kitty.c
--- a/image-sixel.c
+++ b/image-sixel.c
--- a/image.c
+++ b/image.c
--- a/input.c
+++ b/input.c
@@ -145,6 +145,9 @@ struct input_ctx {
 	 */
 	struct evbuffer			*since_ground;
 	struct event			 ground_timer;
+#ifdef ENABLE_IMAGES
+	void				*kitty_state;
+#endif
 };

 /* Helper functions. */
@@ -183,6 +186,9 @@ static void	input_enter_osc(struct input_ctx *);
 static void	input_exit_osc(struct input_ctx *);
 static void	input_enter_apc(struct input_ctx *);
 static void	input_exit_apc(struct input_ctx *);
+#ifdef ENABLE_IMAGES
+static int	input_handle_kitty(struct input_ctx *, const u_char *, size_t);
+#endif
 static void	input_enter_rename(struct input_ctx *);
 static void	input_exit_rename(struct input_ctx *);

@@ -916,6 +922,9 @@ input_free(struct input_ctx *ictx)
 	event_del(&ictx->request_timer);

 	free(ictx->input_buf);
+#ifdef ENABLE_IMAGES
+	kitty_free_state(ictx->kitty_state);
+#endif
 	evbuffer_free(ictx->since_ground);
 	event_del(&ictx->ground_timer);

@@ -938,6 +947,7 @@ input_reset(struct input_ctx *ictx, int clear)
 			screen_write_start_pane(sctx, wp, &wp->base);
 		else
 			screen_write_start(sctx, &wp->base);
+		sctx->flags |= SCREEN_WRITE_INPUT;
 		screen_write_reset(sctx);
 		screen_write_stop(sctx);
 	}
@@ -1065,6 +1075,7 @@ input_parse_buffer(struct window_pane *wp, const u_char *buf, size_t len)
 		screen_write_start_pane(sctx, wp, &wp->base);
 	else
 		screen_write_start(sctx, &wp->base);
+	sctx->flags |= SCREEN_WRITE_INPUT;

 	log_debug("%s: %%%u %s, %zu bytes: %.*s", __func__, wp->id,
 	    ictx->state->name, len, (int)len, buf);
@@ -1084,6 +1095,7 @@ input_parse_screen(struct input_ctx *ictx, struct screen *s,
 		return;

 	screen_write_start_callback(sctx, s, cb, arg);
+	sctx->flags |= SCREEN_WRITE_INPUT;
 	input_parse(ictx, buf, len);
 	screen_write_stop(sctx);
 }
@@ -1583,7 +1595,7 @@ input_csi_dispatch(struct input_ctx *ictx)
 		case -1:
 			break;
 		case 0:
-#ifdef ENABLE_SIXEL
+#ifdef ENABLE_IMAGES
 			input_reply(ictx, 1, "\033[?1;2;4c");
 #else
 			input_reply(ictx, 1, "\033[?1;2c");
@@ -2101,7 +2113,7 @@ input_csi_dispatch_sm_private(struct input_ctx *ictx)
 static void
 input_csi_dispatch_sm_graphics(__unused struct input_ctx *ictx)
 {
-#ifdef ENABLE_SIXEL
+#ifdef ENABLE_IMAGES
 	int	n, m, o;

 	if (ictx->param_list_len > 3)
@@ -2626,10 +2638,10 @@ input_dcs_dispatch(struct input_ctx *ictx)
 	const char		 prefix[] = "tmux;";
 	const u_int		 prefixlen = (sizeof prefix) - 1;
 	long long		 allow_passthrough = 0;
-#ifdef ENABLE_SIXEL
+#ifdef ENABLE_IMAGES
 	struct window		*w;
 	struct sixel_image	*si;
-	int			 p2;
+	int			 p1, p2;
 #endif

 	if (wp == NULL)
@@ -2642,15 +2654,18 @@ input_dcs_dispatch(struct input_ctx *ictx)
 		return (0);
 	}

-#ifdef ENABLE_SIXEL
+#ifdef ENABLE_IMAGES
 	if (wp != NULL && buf[0] == 'q' && ictx->interm_len == 0) {
 		w = wp->window;
 		if (input_split(ictx) != 0)
 			return (0);
+		p1 = input_get(ictx, 0, 0, 0);
+		if (p1 == -1)
+			p1 = 0;
 		p2 = input_get(ictx, 1, 0, 0);
 		if (p2 == -1)
 			p2 = 0;
-		si = sixel_parse(buf, len, p2, w->xpixel, w->ypixel);
+		si = sixel_parse(buf, len, p1, p2, w->xpixel, w->ypixel);
 		if (si != NULL)
 			screen_write_sixelimage(sctx, si, ictx->cell.cell.bg);
 	}
@@ -2789,6 +2804,57 @@ input_enter_apc(struct input_ctx *ictx)
 }

 /* APC terminator (ST) received. */
+#ifdef ENABLE_IMAGES
+static int
+input_handle_kitty(struct input_ctx *ictx, const u_char *buf, size_t len)
+{
+	struct screen_write_ctx	*sctx = &ictx->ctx;
+	struct window_pane	*wp = ictx->wp;
+	struct image		*im;
+	u_int			 image_id = 0, replace_id = 0, quiet = 0;
+	u_int			 placement_id = 0;
+	int32_t			 z = 0;
+	char			 action = '\0', delete = '\0';
+	int			 status;
+
+	if (wp == NULL)
+		return (0);
+	im = kitty_parse_image(&ictx->kitty_state, buf, len,
+		    wp->window->xpixel,
+		    wp->window->ypixel, &image_id, &replace_id, &quiet, &action,
+		    &delete, &placement_id, &z, &status);
+	if (status == KITTY_PARSE_MORE)
+		return (1);
+	if (status != KITTY_PARSE_OK) {
+		if (quiet < 2 && action != '\0') {
+			if (status == KITTY_PARSE_MISSING)
+				input_reply(ictx, 0, "\033_Gi=%u;ENOENT\033\\",
+				    image_id);
+			else
+				input_reply(ictx, 0, "\033_Gi=%u;EINVAL\033\\",
+				    image_id);
+		}
+		return (1);
+	}
+	if (replace_id != 0)
+		image_clear(sctx, replace_id);
+	if (im != NULL) {
+		if (action == 'd')
+			image_clear_kitty(sctx, delete, image_id, placement_id, z);
+		else
+			image_write_kitty(sctx, im, ictx->cell.cell.bg, image_id,
+			    placement_id, z);
+		image_free(image_get_id(im));
+		if (quiet == 0 && image_id != 0)
+			input_reply(ictx, 0, "\033_Gi=%u;OK\033\\", image_id);
+	} else if (action == 'd')
+		image_clear_kitty(sctx, delete, image_id, placement_id, z);
+	else if ((action == 't' || action == 'q' || action == 'u') && quiet == 0)
+		input_reply(ictx, 0, "\033_Gi=%u;OK\033\\", image_id);
+	return (1);
+}
+#endif
+
 static void
 input_exit_apc(struct input_ctx *ictx)
 {
@@ -2799,6 +2865,13 @@ input_exit_apc(struct input_ctx *ictx)
 		return;
 	log_debug("%s: \"%s\"", __func__, ictx->input_buf);

+#ifdef ENABLE_IMAGES
+	if (ictx->input_len > 1 && ictx->input_buf[0] == 'G' &&
+	    input_handle_kitty(ictx, ictx->input_buf + 1,
+	    ictx->input_len - 1))
+		return;
+#endif
+
 	if (wp != NULL &&
 	    options_get_number(wp->options, "allow-set-title") &&
 	    screen_set_title(sctx->s, ictx->input_buf, 1)) {
@@ -2859,6 +2932,12 @@ input_top_bit_set(struct input_ctx *ictx)
 {
 	struct screen_write_ctx	*sctx = &ictx->ctx;
 	struct utf8_data	*ud = &ictx->utf8data;
+#ifdef ENABLE_IMAGES
+	struct grid_cell	 gc;
+	struct image		*im;
+	u_int			 x, source_x, source_y, image_id, placement_id;
+	int32_t			 z;
+#endif

 	ictx->flags &= ~INPUT_LAST;

@@ -2886,6 +2965,20 @@ input_top_bit_set(struct input_ctx *ictx)
 	utf8_copy(&ictx->cell.cell.data, ud);
 	screen_write_collect_add(sctx, &ictx->cell.cell);

+#ifdef ENABLE_IMAGES
+	if (sctx->s->cx != 0) {
+		x = sctx->s->cx - 1; /* cx-1 is the cell just written. */
+		grid_view_get_cell(sctx->s->grid, x, sctx->s->cy, &gc);
+		if (kitty_placeholder_to_image(ictx->kitty_state,
+		    sctx->s->grid, &gc, x, sctx->s->cy, &im, &source_x,
+		    &source_y, &image_id, &placement_id, &z)) {
+			grid_view_set_cell(sctx->s->grid, x, sctx->s->cy, &gc);
+			image_place_cell_kitty(sctx, im, x, sctx->s->cy, source_x,
+			    source_y, image_id, placement_id, z);
+		}
+	}
+#endif
+
 	utf8_copy(&ictx->last, &ictx->cell.cell.data);
 	ictx->flags |= INPUT_LAST;

--- a/options-table.c
+++ b/options-table.c
@@ -541,6 +541,7 @@ const struct options_table_entry options_table[] = {
 	  .scope = OPTIONS_TABLE_SERVER,
 	  .flags = OPTIONS_TABLE_IS_ARRAY,
 	  .default_str = "xterm*:clipboard:ccolour:cstyle:focus:title,"
+			 "xterm-kitty*:kitty,"
 			 "screen*:title,"
 			 "rxvt*:ignorefkeys",
 	  .separator = ",",
--- a/regress/image-support.sh
+++ b/regress/image-support.sh
@@ -0,0 +1,437 @@
+#!/bin/sh
+
+# Grid-resident image layers: Kitty input, history, copy and overwrite.
+
+PATH=/bin:/usr/bin
+TERM=screen
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -Limage$$ -f/dev/null"
+TMUX2="$TEST_TMUX -Limage-client$$ -f/dev/null"
+$TMUX kill-server 2>/dev/null
+$TMUX2 kill-server 2>/dev/null
+
+TMP=$(mktemp)
+FIXTURE=$(pwd)/monkey-2.sixel.txt
+trap "$TMUX kill-server 2>/dev/null; $TMUX2 kill-server 2>/dev/null; rm -f $TMP" 0 1 15
+
+$TMUX new-session -d -x 20 -y 8 "
+	printf '\033_Ga=T,q=2,f=32,s=2,v=2,c=2,r=2,m=1;/wAA/wD/\033\\'
+	printf '\033_Gm=0;AP8AAP///////w==\033\\'
+	i=0
+	while [ \$i -lt 10 ]; do printf '\nline-%d' \$i; i=\$((i + 1)); done
+	sleep 10"
+
+sleep 1
+[ "$($TMUX display-message -p '#{image_support}')" = 0 ] && exit 0
+
+# Images scroll as grid cells, while capture output contains ordinary spaces.
+[ "$($TMUX display-message -p '#{history_size}')" -gt 0 ] || exit 1
+$TMUX capture-pane -pS- >$TMP || exit 1
+grep '_G' $TMP >/dev/null && exit 1
+
+# Copy mode duplicates the backing grid, including image layers.
+$TMUX copy-mode || exit 1
+$TMUX send-keys -X history-top || exit 1
+$TMUX capture-pane -p >$TMP || exit 1
+$TMUX send-keys -X cancel || exit 1
+
+# Ordinary text updates the image underlay through the normal grid write path.
+# Deleting the image reveals the newly written text.
+$TMUX new-window -d "
+	printf '\033_Ga=T,q=2,f=32,s=2,v=2,c=2,r=2,i=8;/wAA/wD/AP8AAP///////w==\033\\'
+	printf '\033[HXY'
+	printf '\033_Ga=d,d=i,q=2,i=8\033\\'
+	sleep 10"
+sleep 1
+[ "$($TMUX capture-pane -pt:1 -S0 -E0)" = "XY" ] || exit 1
+
+# The protocol default is transmit-only; a later placement uses the retained
+# immutable image and advances by the same canonical one-cell footprint.
+$TMUX new-window -d "
+	printf '\033_Gq=2,f=32,s=1,v=1,c=1,r=1,i=9;/wAA/w==\033\\'
+	printf '\033_Ga=p,q=2,i=9\033\\'
+	printf '\033_Ga=d,d=I,q=2,i=9\033\\'
+	sleep 10"
+sleep 1
+[ "$($TMUX display-message -pt:2 '#{cursor_y}')" = 1 ] || exit 1
+
+# PNG Kitty input uses the shared image decoder and canonical cell sizing.
+$TMUX new-window -d "
+	printf '\033_Ga=T,q=2,f=100;iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAIGNIUk0AAHomAACAhAAA+gAAAIDoAAB1MAAA6mAAADqYAAAXcJy6UTwAAAAGUExURf8AAP///0EdNBEAAAABYktHRAH/Ai3eAAAAB3RJTUUH6ggCDAECH324BwAAAApJREFUCNdjYAAAAAIAAeIhvDMAAAAASUVORK5CYII=\033\\'
+	sleep 10"
+sleep 1
+[ "$($TMUX display-message -pt:3 '#{cursor_y}')" = 1 ] || exit 1
+
+# SIXEL input reaches the same grid layer and copy-mode paths.
+$TMUX new-window -d "cat '$FIXTURE'; sleep 10"
+sleep 1
+[ "$($TMUX display-message -pt:4 '#{cursor_y}')" -gt 0 ] || exit 1
+$TMUX copy-mode -t:4 || exit 1
+$TMUX send-keys -t:4 -X history-top || exit 1
+$TMUX capture-pane -pt:4 >$TMP || exit 1
+
+# A 26-pixel raster occupies two default 16-pixel cells, but the final cell
+# remains only partially filled instead of stretching the raster to 32 pixels.
+# A client without an image feature exposes this in the sampled text backend.
+$TMUX kill-server 2>/dev/null
+$TMUX2 new-session -d -x 10 -y 4 "
+	printf '\033Pq\"1;1;26;26#0;2;100;100;100#0!26~-!26~-!26~-!26~-!26B\033\\'
+	sleep 10" || exit 1
+$TMUX2 set -g status off || exit 1
+$TMUX2 set -as terminal-features ',*:sixel' || exit 1
+$TMUX new-session -d -x 10 -y 4 || exit 1
+$TMUX set -g status off || exit 1
+$TMUX pipe-pane -O "cat >$TMP" || exit 1
+$TMUX send-keys -l "$TMUX2 attach-session" || exit 1
+$TMUX send-keys Enter || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E0 >$TMP || exit 1
+grep -q '^#=' $TMP || exit 1
+
+# Re-emitting the image preserves the 26-pixel raster rather than expanding
+# it to the two complete 16-pixel grid cells occupied by the image.
+$TMUX pipe-pane || exit 1
+$TMUX pipe-pane -O "cat >$TMP" || exit 1
+$TMUX2 refresh-client -R || exit 1
+sleep 1
+grep -a '"1;1;26;26' $TMP >/dev/null || exit 1
+
+# A selection redraw uses the single-cell path. It must leave ASCII image
+# cells visible (graphical clients skip these cells to avoid erasing pixels).
+$TMUX2 copy-mode || exit 1
+$TMUX2 send-keys -X history-top || exit 1
+$TMUX2 send-keys -X start-of-line || exit 1
+$TMUX2 send-keys -N 4 -X cursor-right || exit 1
+$TMUX2 send-keys -X begin-selection || exit 1
+$TMUX pipe-pane || exit 1
+$TMUX pipe-pane -O "cat >$TMP" || exit 1
+$TMUX2 send-keys -X cursor-right || exit 1
+sleep 1
+$TMUX pipe-pane || exit 1
+grep -a '"1;1;' $TMP >/dev/null && exit 1
+$TMUX capture-pane -pS0 -E0 >$TMP || exit 1
+grep -q '^#=' $TMP || exit 1
+
+# Selection must also leave transparent cells inside the image canvas alone.
+# This 26-pixel canvas paints only its first pixel column, while the text below
+# it keeps the copy-mode cursor movable across both occupied terminal cells.
+$TMUX2 send-keys -X cancel || exit 1
+$TMUX2 new-window -d "
+	printf 'ab\r'
+	printf '\033Pq\"1;1;26;26#0;2;100;100;100#0~-#0~-#0~-#0~-#0B\033\\'
+	sleep 10" || exit 1
+$TMUX2 select-window -t:1 || exit 1
+sleep 1
+$TMUX2 copy-mode || exit 1
+$TMUX2 send-keys -X top-line || exit 1
+$TMUX2 send-keys -X start-of-line || exit 1
+$TMUX2 send-keys -X cursor-right || exit 1
+$TMUX2 send-keys -X begin-selection || exit 1
+$TMUX pipe-pane || exit 1
+$TMUX pipe-pane -O "cat >$TMP" || exit 1
+$TMUX2 send-keys -X cursor-right || exit 1
+sleep 1
+$TMUX pipe-pane || exit 1
+grep -a 'b' $TMP >/dev/null && exit 1
+
+# Scrolling moves the terminal's image rows with its text rows. It must not
+# force tmux to erase and retransmit the complete SIXEL image.
+$TMUX2 send-keys -X cancel || exit 1
+SCROLL_WINDOW=$($TMUX2 new-window -P -F '#{window_id}' \
+    "cat '$FIXTURE'; exec sh") || exit 1
+sleep 1
+$TMUX pipe-pane || exit 1
+$TMUX pipe-pane -O "cat >$TMP" || exit 1
+$TMUX2 send-keys -t"$SCROLL_WINDOW" -l \
+    "i=0; while [ \$i -lt 12 ]; do printf 'scroll-marker-%d\\n' \$i; i=\$((i + 1)); done" || exit 1
+$TMUX2 send-keys -t"$SCROLL_WINDOW" Enter || exit 1
+sleep 1
+grep -a 'scroll-marker-11' $TMP >/dev/null || exit 1
+grep -a '"1;1;' $TMP >/dev/null && exit 1
+
+# A retained Kitty image may be placed repeatedly using source rectangles.
+# Crop the green and white right column from a red/green/blue/white image.
+$TMUX kill-server 2>/dev/null
+$TMUX2 kill-server 2>/dev/null
+$TMUX2 new-session -d -x 10 -y 4 "
+	printf '\033_Ga=t,q=2,f=32,s=2,v=2,i=10;/wAA/wD/AP8AAP///////w==\033\\'
+	printf '\033_Ga=p,q=2,i=10,x=1,y=0,w=1,h=2,c=1,r=2\033\\'
+	sleep 10" || exit 1
+$TMUX2 set -g status off || exit 1
+$TMUX new-session -d -x 10 -y 4 || exit 1
+$TMUX set -g status off || exit 1
+$TMUX send-keys -l "$TMUX2 attach-session" || exit 1
+$TMUX send-keys Enter || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E1 >$TMP || exit 1
+[ "$(sed -n 1p $TMP)" = "*" ] || exit 1
+[ "$(sed -n 2p $TMP)" = "@" ] || exit 1
+
+# C=1 places the image without moving the cursor or scrolling. The four-row
+# image is clipped at the bottom of this four-row pane, leaving its white last
+# row off screen.
+$TMUX2 new-window -d "
+	printf '\033[2;3H'
+	printf '\033_Ga=T,q=2,C=1,f=32,s=1,v=4,c=1,r=4;AAAA/1VVVf+qqqr//////w==\033\\'
+	sleep 10" || exit 1
+$TMUX2 select-window -t:1 || exit 1
+sleep 1
+[ "$($TMUX2 display-message -p '#{cursor_x},#{cursor_y}')" = "2,1" ] || exit 1
+$TMUX capture-pane -pS0 -E3 >$TMP || exit 1
+[ "$(sed -n 3p $TMP)" = "  -" ] || exit 1
+[ "$(sed -n 4p $TMP)" = "  *" ] || exit 1
+
+# With normal cursor movement, scrolling is calculated from the full image
+# height. Rows which scrolled above the pane are then cropped from the top, so
+# the bottom three source rows remain visible and the cursor is on the last row.
+$TMUX2 new-window -d "
+	printf '\033[3;1H'
+	printf '\033_Ga=T,q=2,f=32,s=1,v=4,c=1,r=4;AAAA/1VVVf+qqqr//////w==\033\\'
+	sleep 10" || exit 1
+$TMUX2 select-window -t:2 || exit 1
+sleep 1
+[ "$($TMUX2 display-message -p '#{cursor_y}')" = 3 ] || exit 1
+$TMUX capture-pane -pS0 -E3 >$TMP || exit 1
+[ "$(sed -n 1p $TMP)" = "-" ] || exit 1
+[ "$(sed -n 2p $TMP)" = "*" ] || exit 1
+[ "$(sed -n 3p $TMP)" = "@" ] || exit 1
+
+# Image rows remain cell-aligned when a narrower terminal causes text
+# reflow. The ten-column rows are clipped to five columns, not split into four
+# wrapped rows.
+$TMUX2 new-window -d "
+	printf '\033_Ga=T,q=2,C=1,f=32,s=1,v=2,c=10,r=2;/wAA//////8=\033\\'
+	sleep 10" || exit 1
+$TMUX2 select-window -t:3 || exit 1
+sleep 1
+$TMUX resize-window -x 5 -y 4 || exit 1
+sleep 1
+[ "$($TMUX2 display-message -p '#{window_width}x#{window_height}')" = "5x4" ] || exit 1
+$TMUX capture-pane -pS0 -E3 >$TMP || exit 1
+[ "$(sed -n 1p $TMP)" = "....." ] || exit 1
+[ "$(sed -n 2p $TMP)" = "@@@@@" ] || exit 1
+[ -z "$(sed -n 3p $TMP)" ] || exit 1
+
+# Kitty virtual placements use U+10EEEE placeholder cells. Keep their rows at
+# fixed coordinates when narrowing the terminal, clipping instead of reflowing
+# the second half onto the following row.
+$TMUX resize-window -x 10 -y 4 || exit 1
+sleep 1
+$TMUX2 new-window -d "
+	printf '\\364\\216\\273\\256\\314\\205\\364\\216\\273\\256\\314\\205\\364\\216\\273\\256\\314\\205\\364\\216\\273\\256\\314\\205\\364\\216\\273\\256\\314\\205'
+	printf '\\364\\216\\273\\256\\314\\205\\364\\216\\273\\256\\314\\205\\364\\216\\273\\256\\314\\205\\364\\216\\273\\256\\314\\205\\364\\216\\273\\256\\314\\205'
+	sleep 10" || exit 1
+$TMUX2 select-window -t:4 || exit 1
+sleep 1
+$TMUX resize-window -x 5 -y 4 || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E3 >$TMP || exit 1
+[ -n "$(sed -n 1p $TMP)" ] || exit 1
+[ -z "$(sed -n 2p $TMP)" ] || exit 1
+$TMUX resize-window -x 10 -y 4 || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E3 >$TMP || exit 1
+[ "$(sed -n 1p $TMP | wc -c)" = 61 ] || exit 1
+[ -z "$(sed -n 2p $TMP)" ] || exit 1
+
+# A placement ID supplied with transmit-and-place is reused by a later place.
+# This is the sequence used by chawan: the newline moves the cursor down before
+# the second command, so the folder moves down one row without leaving a copy.
+PLACEMENT_WINDOW=$($TMUX2 new-window -dP -F '#{window_id}' "
+	printf '\033_GC=1,s=26,v=26,p=1,q=2,i=1,a=T,f=100,m=0;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\033\\'
+	printf '\n'
+	sleep 1
+	printf '\033_GC=1,s=26,v=26,p=1,q=2,i=1,a=p;\033\\'
+	printf '\n'
+	sleep 10") || exit 1
+$TMUX2 select-window -t"$PLACEMENT_WINDOW" || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E3 >$TMP || exit 1
+[ -z "$(sed -n 1p $TMP)" ] || exit 1
+[ -n "$(sed -n 2p $TMP)" ] || exit 1
+
+# A nonzero Kitty placement ID identifies one placement of an image. Reusing
+# the same image and placement IDs moves it rather than leaving the old cells.
+PLACEMENT_WINDOW=$($TMUX2 new-window -dP -F '#{window_id}' "
+	printf '\033_Ga=t,q=2,f=32,s=1,v=1,i=11;/////w==\033\\'
+	printf '\033[2;2H\033_Ga=p,q=2,C=1,i=11,p=7,c=2,r=1\033\\'
+	printf '\033[4;6H\033_Ga=p,q=2,C=1,i=11,p=7,c=2,r=1\033\\'
+	sleep 10") || exit 1
+$TMUX2 select-window -t"$PLACEMENT_WINDOW" || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E3 >$TMP || exit 1
+[ -z "$(sed -n 2p $TMP)" ] || exit 1
+[ "$(sed -n 4p $TMP)" = "     @@" ] || exit 1
+
+# Deleting one placement ID leaves other placements of the image intact.
+PLACEMENT_WINDOW=$($TMUX2 new-window -dP -F '#{window_id}' "
+	printf '\033_Ga=t,q=2,f=32,s=1,v=1,i=12;/////w==\033\\'
+	printf '\033[2;2H\033_Ga=p,q=2,C=1,i=12,p=7,c=2,r=1\033\\'
+	printf '\033[4;6H\033_Ga=p,q=2,C=1,i=12,p=8,c=2,r=1\033\\'
+	printf '\033_Ga=d,d=i,q=2,i=12,p=7\033\\'
+	sleep 10") || exit 1
+$TMUX2 select-window -t"$PLACEMENT_WINDOW" || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E3 >$TMP || exit 1
+[ -z "$(sed -n 2p $TMP)" ] || exit 1
+[ "$(sed -n 4p $TMP)" = "     @@" ] || exit 1
+
+# Image layers retain the cells beneath them. Deleting a transparent image
+# must reveal the original text rather than replacing it with spaces.
+PLACEMENT_WINDOW=$($TMUX2 new-window -dP -F '#{window_id}' "
+	printf 'XY'
+	printf '\033[H'
+	printf '\033_Ga=T,q=2,C=1,f=32,s=1,v=1,c=2,r=1,i=13,p=7;////AA==\033\\'
+	printf '\033_Ga=d,d=i,q=2,i=13,p=7\033\\'
+	sleep 10") || exit 1
+$TMUX2 select-window -t"$PLACEMENT_WINDOW" || exit 1
+sleep 1
+[ "$($TMUX2 capture-pane -pS0 -E0)" = "XY" ] || exit 1
+
+# Text written over a Kitty placement updates its underlay without deleting
+# the image. Deleting the placement afterwards reveals the updated text.
+TEXT_WINDOW=$($TMUX2 new-window -dP -F '#{window_id}' "
+	printf 'test\r'
+	printf '\033_Ga=T,q=2,C=1,f=32,s=2,v=2,c=2,r=2,i=14,p=7;/wAA/wD/AP8AAP///////w==\033\\'
+	printf '\r'
+	printf 'test\n'
+	printf 'test\n'
+	$TEST_TMUX wait-for image-text-delete-$$
+	printf '\033_Ga=d,d=i,q=2,i=14,p=7\033\\'
+	sleep 10") || exit 1
+$TMUX2 select-window -t"$TEXT_WINDOW" || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E1 >$TMP || exit 1
+[ "$(sed -n 1p $TMP)" = ".*st" ] || exit 1
+[ "$(sed -n 2p $TMP)" = " @st" ] || exit 1
+$TMUX2 wait-for -S image-text-delete-$$ || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E1 >$TMP || exit 1
+[ "$(sed -n 1p $TMP)" = "test" ] || exit 1
+[ "$(sed -n 2p $TMP)" = "test" ] || exit 1
+
+# Kitty z-indexes and SIXEL's temporal plane are properties of the input, not
+# of the outer terminal. Exercise the logical scene through the fallback
+# backend: higher nonnegative z-indexes cover lower ones and text, ordinary
+# negative z-indexes cover backgrounds but not text, and very negative ones
+# remain below the background.
+Z_WINDOW=$($TMUX2 new-window -dP -F '#{window_id}' "
+	printf '\033_Ga=t,q=2,f=32,s=1,v=1,i=21;/wAA/w==\033\\'
+	printf '\033_Ga=t,q=2,f=32,s=1,v=1,i=22;/////w==\033\\'
+	printf 'X\r'
+	printf '\033_Ga=p,q=2,C=1,i=21,p=1,z=2,c=1,r=1\033\\'
+	printf '\033_Ga=p,q=2,C=1,i=22,p=2,z=1,c=1,r=1\033\\'
+	printf '\033[2;1H\033[41m \033[0m\r'
+	printf '\033_Ga=p,q=2,C=1,i=21,p=3,z=-1,c=1,r=1\033\\'
+	printf '\033[3;1HY\r'
+	printf '\033_Ga=p,q=2,C=1,i=21,p=4,z=-1,c=1,r=1\033\\'
+	printf '\033[4;1H\033[41m \033[0m\r'
+	printf '\033_Ga=p,q=2,C=1,i=21,p=5,z=-1073741825,c=1,r=1\033\\'
+	$TEST_TMUX wait-for image-z-top-$$
+	printf '\033_Ga=d,d=z,q=2,z=2\033\\'
+	$TEST_TMUX wait-for image-z-lower-$$
+	printf '\033_Ga=d,d=z,q=2,z=1\033\\'
+	sleep 10") || exit 1
+$TMUX2 select-window -t"$Z_WINDOW" || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E3 >$TMP || exit 1
+[ "$(sed -n 1p $TMP)" = "." ] || exit 1
+[ "$(sed -n 2p $TMP)" = "." ] || exit 1
+[ "$(sed -n 3p $TMP)" = "Y" ] || exit 1
+[ -z "$(sed -n 4p $TMP)" ] || exit 1
+$TMUX2 wait-for -S image-z-top-$$ || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E0 >$TMP || exit 1
+[ "$(sed -n 1p $TMP)" = "@" ] || exit 1
+$TMUX2 wait-for -S image-z-lower-$$ || exit 1
+sleep 1
+$TMUX capture-pane -pS0 -E0 >$TMP || exit 1
+[ "$(sed -n 1p $TMP)" = "X" ] || exit 1
+
+# A weighted median at the maximum channel level must still leave colours on
+# both sides of the split. This skewed black, grey and white image used to stop
+# palette generation after one colour instead of producing three.
+$TMUX kill-server 2>/dev/null
+$TMUX2 kill-server 2>/dev/null
+$TMUX2 new-session -d -x 20 -y 4 "
+	printf '\033_Ga=T,q=2,C=1,f=24,s=100,v=1,c=10,r=1;AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICA////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////\033\\'
+	sleep 10" || exit 1
+$TMUX2 set -g status off || exit 1
+$TMUX2 set -as terminal-features ',*:sixel' || exit 1
+$TMUX new-session -d -x 20 -y 4 || exit 1
+$TMUX set -g status off || exit 1
+$TMUX pipe-pane -O "cat >$TMP" || exit 1
+$TMUX send-keys -l "$TMUX2 attach-session" || exit 1
+$TMUX send-keys Enter || exit 1
+sleep 1
+grep -a '#2;2;' $TMP >/dev/null || exit 1
+
+# A pane redraw on a SIXEL terminal must not clear the status line, which is
+# outside the window scene and may not be redrawn after the pane scrolls.
+$TMUX kill-server 2>/dev/null
+$TMUX2 kill-server 2>/dev/null
+$TMUX2 new-session -d -x 20 -y 8 || exit 1
+$TMUX2 set -g 'status-format[0]' 'STATUS' || exit 1
+$TMUX2 set -as terminal-features ',*:sixel' || exit 1
+$TMUX new-session -d -x 20 -y 8 || exit 1
+$TMUX set -g status off || exit 1
+$TMUX send-keys -l "$TMUX2 attach-session" || exit 1
+$TMUX send-keys Enter || exit 1
+sleep 1
+$TMUX2 send-keys -l 'seq 30' || exit 1
+$TMUX2 send-keys Enter || exit 1
+sleep 1
+$TMUX capture-pane -p >$TMP || exit 1
+[ "$(tail -n 1 $TMP)" = "STATUS" ] || exit 1
+
+# A partial redraw of a tiled pane must clear only its visible scene spans.
+# Clearing its entire rectangle would erase a floating pane above it, while
+# the tiled pane redraw correctly skips the obscured area and cannot restore it.
+$TMUX kill-server 2>/dev/null
+$TMUX2 kill-server 2>/dev/null
+$TMUX2 new-session -d -x 40 -y 15 \
+    "printf 'TILED PANE'; sleep 10" || exit 1
+TILED_PANE=$($TMUX2 display-message -p '#{pane_id}') || exit 1
+FLOATING_PANE=$($TMUX2 new-pane -dP -F '#{pane_id}' -x 20 -y 6 -X 10 -Y 4 \
+    "printf 'FLOATING PANE'; sleep 10") || exit 1
+$TMUX2 set -g status off || exit 1
+$TMUX2 set -as terminal-features ',*:sixel' || exit 1
+$TMUX2 select-pane -t"$FLOATING_PANE" || exit 1
+$TMUX new-session -d -x 40 -y 15 || exit 1
+$TMUX set -g status off || exit 1
+$TMUX send-keys -l "$TMUX2 attach-session" || exit 1
+$TMUX send-keys Enter || exit 1
+sleep 1
+$TMUX2 copy-mode -t"$TILED_PANE" || exit 1
+sleep 1
+$TMUX capture-pane -p >$TMP || exit 1
+grep 'TILED PANE' $TMP >/dev/null || exit 1
+grep 'FLOATING PANE' $TMP >/dev/null || exit 1
+
+# An obscured pane is normally redrawn a line at a time when it scrolls, but
+# that path cannot restore graphical image layers. It must defer to the scene
+# redraw so the visible part of the image is emitted around the floating pane.
+IMAGE_PANE=$($TMUX2 new-window -dP -F '#{pane_id}' \
+    "cat '$FIXTURE'; exec sh") || exit 1
+$TMUX2 set -g pane-border-status top || exit 1
+$TMUX2 set -pt"$IMAGE_PANE" pane-border-format 'IMAGE STATUS' || exit 1
+FLOATING_PANE=$($TMUX2 new-pane -dP -F '#{pane_id}' -x 20 -y 6 -X 10 -Y 4 \
+    "printf 'FLOATING PANE'; sleep 10") || exit 1
+$TMUX2 set -pt"$FLOATING_PANE" pane-border-format 'FLOAT STATUS' || exit 1
+$TMUX2 select-pane -t"$FLOATING_PANE" || exit 1
+sleep 1
+$TMUX pipe-pane || exit 1
+$TMUX pipe-pane -O "cat >$TMP" || exit 1
+$TMUX2 send-keys -t"$IMAGE_PANE" -l \
+    "i=0; while [ \$i -lt 5 ]; do printf 'image-scroll-%d\\n' \$i; i=\$((i + 1)); done" || exit 1
+$TMUX2 send-keys -t"$IMAGE_PANE" Enter || exit 1
+sleep 1
+$TMUX pipe-pane || exit 1
+grep -a 'image-scroll-4' $TMP >/dev/null || exit 1
+grep -a '"1;1;' $TMP >/dev/null || exit 1
+$TMUX capture-pane -p >$TMP || exit 1
+grep 'IMAGE STATUS' $TMP >/dev/null || exit 1
+grep 'FLOAT STATUS' $TMP >/dev/null || exit 1
+
+exit 0
--- a/regress/monkey-2.sixel.txt
+++ b/regress/monkey-2.sixel.txt
--- a/resize.c
+++ b/resize.c
@@ -386,10 +386,12 @@ recalculate_size(struct window *w, int now)
 	 * got a resize scheduled, then use the new size; otherwise the old.
 	 */
 	if (w->flags & WINDOW_RESIZE) {
-		if (!now && changed && w->new_sx == sx && w->new_sy == sy)
+		if (!now && changed && w->new_sx == sx && w->new_sy == sy &&
+		    w->new_xpixel == xpixel && w->new_ypixel == ypixel)
 			changed = 0;
 	} else {
-		if (!now && changed && w->sx == sx && w->sy == sy)
+		if (!now && changed && w->sx == sx && w->sy == sy &&
+		    w->xpixel == xpixel && w->ypixel == ypixel)
 			changed = 0;
 	}

--- a/screen-redraw.c
+++ b/screen-redraw.c
@@ -99,6 +99,13 @@ enum redraw_span_type {
 #define REDRAW_ALL 0x7fffffff
 #define REDRAW_IS_ALL(flags) ((flags) == REDRAW_ALL)

+enum redraw_image_phase {
+	REDRAW_IMAGES_BEFORE,
+	REDRAW_TEXT,
+	REDRAW_IMAGES_AFTER,
+	REDRAW_CHROME
+};
+
 /* UTF-8 isolate characters. */
 #define REDRAW_START_ISOLATE "\342\201\246"
 #define REDRAW_END_ISOLATE "\342\201\251"
@@ -1106,7 +1113,8 @@ redraw_get_scene(struct client *c)
 /* Draw a pane span. */
 static void
 redraw_draw_pane_span(struct redraw_draw_ctx *dctx,
-    struct redraw_span *span, u_int x, u_int y, u_int n)
+    struct redraw_span *span, u_int x, u_int y, u_int n,
+    enum redraw_image_phase phase)
 {
 	struct redraw_scene	*scene = dctx->scene;
 	struct client		*c = scene->c;
@@ -1124,7 +1132,14 @@ redraw_draw_pane_span(struct redraw_draw_ctx *dctx,

 	px = span->data.p.px + (x - span->x);
 	py = span->data.p.py;
-	tty_draw_line(tty, s, px, py, n, x, y, &style_ctx);
+#ifdef ENABLE_IMAGES
+	if (phase != REDRAW_TEXT)
+		image_draw_line(tty, s, px, py, n, x, y,
+		    phase == REDRAW_IMAGES_BEFORE, &style_ctx);
+	else
+#endif
+	if (phase == REDRAW_TEXT)
+		tty_draw_line(tty, s, px, py, n, x, y, &style_ctx);
 }

 /* Get default border style for spans without a pane. */
@@ -1379,7 +1394,7 @@ redraw_draw_menu_span(struct redraw_draw_ctx *dctx,
 /* Draw a span. */
 static void
 redraw_draw_span(struct redraw_draw_ctx *dctx, struct redraw_span *span,
-    u_int y)
+    u_int y, enum redraw_image_phase phase)
 {
 	struct redraw_scene	*scene = dctx->scene;
 	struct redraw_span_data	*data = &span->data;
@@ -1400,10 +1415,15 @@ redraw_draw_span(struct redraw_draw_ctx *dctx, struct redraw_span *span,
 			continue;
 		x = rr->px;
 		n = rr->nx;
+		if (type == REDRAW_SPAN_PANE) {
+			if (phase == REDRAW_CHROME)
+				continue;
+		} else if (phase != REDRAW_CHROME)
+			continue;

 		switch (span->data.type) {
 		case REDRAW_SPAN_PANE:
-			redraw_draw_pane_span(dctx, span, x, y, n);
+			redraw_draw_pane_span(dctx, span, x, y, n, phase);
 			break;
 		case REDRAW_SPAN_BORDER:
 		case REDRAW_SPAN_EMPTY:
@@ -1432,6 +1452,11 @@ redraw_draw_pane_lines(struct redraw_draw_ctx *dctx, struct window_pane *wp,
 	struct redraw_line	*line;
 	struct redraw_spans	*spans;
 	struct redraw_span	*span;
+#ifdef ENABLE_IMAGES
+	struct visible_ranges	*r;
+	struct visible_range	*rr;
+	u_int			 i;
+#endif
 	u_int			 cy;
 	int			 y, top, bottom;

@@ -1444,24 +1469,53 @@ redraw_draw_pane_lines(struct redraw_draw_ctx *dctx, struct window_pane *wp,
 	if (bottom > (int)scene->sy)
 		bottom = scene->sy;

-	for (y = top; y < bottom; y++) {
-		line = &scene->lines[y];
-		if (dctx->flags & REDRAW_STATUS_TOP)
-			cy = dctx->status_lines + y;
-		else
+#ifdef ENABLE_IMAGES
+	if (flags & REDRAW_PANE) {
+		for (y = top; y < bottom; y++) {
+			line = &scene->lines[y];
 			cy = y;
-		if (flags & REDRAW_PANE) {
+			if (dctx->flags & REDRAW_STATUS_TOP)
+				cy += dctx->status_lines;
 			spans = &line->spans[REDRAW_SPAN_PANE];
 			TAILQ_FOREACH(span, spans, entry) {
-				if (span->data.p.wp == wp)
-					redraw_draw_span(dctx, span, cy);
+				if (span->data.p.wp != wp)
+					continue;
+				r = tty_check_overlay_range(&scene->c->tty,
+				    span->x, cy, span->width);
+				for (i = 0; i < r->used; i++) {
+					rr = &r->ranges[i];
+					if (rr->nx != 0) {
+						image_redraw_start(&scene->c->tty,
+						    rr->px, cy, rr->nx, 1);
+					}
+				}
 			}
 		}
-		if (flags & REDRAW_PANE_SCROLLBAR) {
-			spans = &line->spans[REDRAW_SPAN_SCROLLBAR];
-			TAILQ_FOREACH(span, spans, entry) {
-				if (span->data.sb.wp == wp)
-					redraw_draw_span(dctx, span, cy);
+	}
+#endif
+
+	for (enum redraw_image_phase phase = REDRAW_IMAGES_BEFORE;
+	    phase <= REDRAW_CHROME; phase++) {
+		for (y = top; y < bottom; y++) {
+			line = &scene->lines[y];
+			if (dctx->flags & REDRAW_STATUS_TOP)
+				cy = dctx->status_lines + y;
+			else
+				cy = y;
+			if (flags & REDRAW_PANE) {
+				spans = &line->spans[REDRAW_SPAN_PANE];
+				TAILQ_FOREACH(span, spans, entry) {
+					if (span->data.p.wp == wp)
+						redraw_draw_span(dctx, span, cy, phase);
+				}
+			}
+			if (phase == REDRAW_CHROME &&
+			    (flags & REDRAW_PANE_SCROLLBAR)) {
+				spans = &line->spans[REDRAW_SPAN_SCROLLBAR];
+				TAILQ_FOREACH(span, spans, entry) {
+					if (span->data.sb.wp == wp)
+						redraw_draw_span(dctx, span, cy, phase);
+				}
 			}
 		}
 	}
@@ -1477,13 +1531,15 @@ redraw_draw_lines(struct redraw_draw_ctx *dctx, int flags)
 	struct redraw_span	*span;
 	u_int			 y, cy, type;

-	for (y = 0; y < scene->sy; y++) {
-		line = &scene->lines[y];
-		if (dctx->flags & REDRAW_STATUS_TOP)
-			cy = dctx->status_lines + y;
-		else
-			cy = y;
-		for (type = 0; type < REDRAW_SPAN_TYPES; type++) {
+	for (enum redraw_image_phase phase = REDRAW_IMAGES_BEFORE;
+	    phase <= REDRAW_CHROME; phase++) {
+		for (y = 0; y < scene->sy; y++) {
+			line = &scene->lines[y];
+			if (dctx->flags & REDRAW_STATUS_TOP)
+				cy = dctx->status_lines + y;
+			else
+				cy = y;
+			for (type = 0; type < REDRAW_SPAN_TYPES; type++) {
 			if (!REDRAW_IS_ALL(flags)) {
 				switch (type) {
 				case REDRAW_SPAN_PANE:
@@ -1520,7 +1576,8 @@ redraw_draw_lines(struct redraw_draw_ctx *dctx, int flags)
 			}
 			spans = &line->spans[type];
 			TAILQ_FOREACH(span, spans, entry)
-				redraw_draw_span(dctx, span, cy);
+				redraw_draw_span(dctx, span, cy, phase);
+			}
 		}
 	}
 }
@@ -1541,7 +1598,7 @@ redraw_draw_menu_lines(struct redraw_draw_ctx *dctx)
 		else
 			cy = y;
 		TAILQ_FOREACH(span, &line->spans[REDRAW_SPAN_MENU], entry)
-			redraw_draw_span(dctx, span, cy);
+			redraw_draw_span(dctx, span, cy, REDRAW_TEXT);
 	}
 }

@@ -1731,9 +1788,10 @@ redraw_draw(struct client *c, struct window_pane *wp, int flags)
 	}

 	if (flags & REDRAW_PANE_STATUS) {
-		redraw = 0;
+		redraw = !!(flags & REDRAW_PANE_BORDER);
 		TAILQ_FOREACH(loop, &scene->w->panes, entry) {
-			if (REDRAW_IS_ALL(flags))
+			if (REDRAW_IS_ALL(flags) ||
+			    (flags & REDRAW_PANE_BORDER))
 				loop->flags |= PANE_NEWSTATUS;
 			else
 				loop->flags &= ~PANE_NEWSTATUS;
@@ -1771,6 +1829,14 @@ redraw_draw(struct client *c, struct window_pane *wp, int flags)
 		}
 	}
 	tty_sync_start(tty);
+#ifdef ENABLE_IMAGES
+	if (wp == NULL && (flags & REDRAW_PANE)) {
+		y = 0;
+		if (dctx.flags & REDRAW_STATUS_TOP)
+			y = dctx.status_lines;
+		image_redraw_start(tty, 0, y, scene->sx, scene->sy);
+	}
+#endif
 	tty_update_mode(tty, tty->mode & ~CURSOR_MODES, NULL);

 	if (wp != NULL)
@@ -1817,15 +1883,6 @@ redraw_draw(struct client *c, struct window_pane *wp, int flags)
 	tty_reset(tty);
 	tty_sync_end(tty);

-#ifdef ENABLE_SIXEL
-	if (wp != NULL)
-		tty_draw_images(c, wp);
-	else {
-		TAILQ_FOREACH(loop, &scene->w->panes, entry)
-			tty_draw_images(c, loop);
-	}
-#endif
-
 	log_debug("%s: finished @%u redraw", c->name, scene->w->id);
 }

--- a/screen-write.c
+++ b/screen-write.c
@@ -34,6 +34,10 @@ static void	screen_write_collect_clear(struct screen_write_ctx *, u_int,
 static void	screen_write_collect_scroll(struct screen_write_ctx *, u_int);
 static void	screen_write_collect_flush(struct screen_write_ctx *, int,
 		    const char *);
+#ifdef ENABLE_IMAGES
+static int	screen_write_image_damage(struct screen_write_ctx *, u_int,
+		    u_int, u_int, u_int);
+#endif
 static int	screen_write_overwrite(struct screen_write_ctx *,
 		    struct grid_cell *, u_int);
 static int	screen_write_combine(struct screen_write_ctx *,
@@ -135,6 +139,8 @@ static int
 screen_write_set_client_cb(struct tty_ctx *ttyctx, struct client *c)
 {
 	struct window_pane	*wp = ttyctx->arg;
+	u_int			 sx, sb_w = 0;
+	int			 xoff;

 	if (ttyctx->flags & TTY_CTX_INVISIBLE_PANES) {
 		if (session_has(c->session, wp->window))
@@ -168,6 +174,21 @@ screen_write_set_client_cb(struct tty_ctx *ttyctx, struct client *c)

 	ttyctx->xoff = ttyctx->rxoff = wp->xoff;
 	ttyctx->yoff = ttyctx->ryoff = wp->yoff;
+	ttyctx->flags &= ~TTY_CTX_PANE_FULL_WIDTH;
+	if (~ttyctx->flags & TTY_CTX_WINDOW_BIGGER &&
+	    !window_has_floating_panes(wp->window)) {
+		xoff = wp->xoff;
+		sx = wp->sx;
+		if (window_pane_scrollbar_reserve(wp)) {
+			sb_w = wp->scrollbar_style.width +
+			    wp->scrollbar_style.pad;
+			sx += sb_w;
+			if (wp->window->sb_pos == PANE_SCROLLBARS_LEFT)
+				xoff -= sb_w;
+		}
+		if (xoff == 0 && sx >= c->tty.sx)
+			ttyctx->flags |= TTY_CTX_PANE_FULL_WIDTH;
+	}

 	if (status_at_line(c) == 0)
 		ttyctx->yoff += status_line_size(c);
@@ -361,6 +382,23 @@ screen_write_init(struct screen_write_ctx *ctx, struct screen *s)
 	ctx->bg = 8;
 }

+#ifdef ENABLE_IMAGES
+/* Damage temporal images when application input writes text cells. */
+static int
+screen_write_image_damage(struct screen_write_ctx *ctx, u_int x, u_int y,
+    u_int sx, u_int sy)
+{
+	int	found;
+
+	if (~ctx->flags & SCREEN_WRITE_INPUT)
+		return (0);
+	found = image_grid_check_area(ctx->s->grid, x,
+	    ctx->s->grid->hsize + y, sx, sy);
+	image_grid_damage(ctx->s->grid, x, ctx->s->grid->hsize + y, sx, sy);
+	return (found);
+}
+#endif
+
 /* Initialize writing with a pane. */
 void
 screen_write_start_pane(struct screen_write_ctx *ctx, struct window_pane *wp,
@@ -1285,15 +1323,14 @@ screen_write_clear_dirty(struct window_pane *wp)
 	}
 }

-/* Redraw all visible cells in a pane. */
+/* Redraw an obscured pane through the scene to preserve floating panes. */
 static void
-screen_write_redraw_pane(struct screen_write_ctx *ctx, struct tty_ctx *ttyctx)
+screen_write_redraw_pane(struct screen_write_ctx *ctx)
 {
-	struct screen	*s = ctx->s;
-	u_int		 yy;
-
-	for (yy = 0; yy < screen_size_y(s); yy++)
-		screen_write_redraw_line(ctx, ttyctx, yy);
+	if (ctx->wp != NULL) {
+		ctx->wp->flags |= PANE_REDRAW;
+		server_redraw_window_borders(ctx->wp->window);
+	}
 }

 /* VT100 alignment test. */
@@ -1308,9 +1345,11 @@ screen_write_alignmenttest(struct screen_write_ctx *ctx)
 	memcpy(&gc, &grid_default_cell, sizeof gc);
 	utf8_set(&gc.data, 'E');

-#ifdef ENABLE_SIXEL
-	if (image_free_all(s) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	image_redraw_all(ctx);
+	if (ctx->flags & SCREEN_WRITE_INPUT)
+		image_grid_damage(s->grid, 0, s->grid->hsize,
+		    screen_size_x(s), screen_size_y(s));
 #endif

 	for (yy = 0; yy < screen_size_y(s); yy++) {
@@ -1334,7 +1373,7 @@ screen_write_alignmenttest(struct screen_write_ctx *ctx)
 		return;
 	}

-	screen_write_redraw_pane(ctx, &ttyctx);
+	screen_write_redraw_pane(ctx);
 }

 /* Insert nx characters. */
@@ -1355,9 +1394,8 @@ screen_write_insertcharacter(struct screen_write_ctx *ctx, u_int nx, u_int bg)
 	if (s->cx > screen_size_x(s) - 1)
 		return;

-#ifdef ENABLE_SIXEL
-	if (image_check_line(s, s->cy, 1) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	image_redraw_area(ctx, 0, s->cy, screen_size_x(s), 1);
 #endif

 	screen_write_initctx(ctx, &ttyctx, 0, 1);
@@ -1396,9 +1434,8 @@ screen_write_deletecharacter(struct screen_write_ctx *ctx, u_int nx, u_int bg)
 	if (s->cx > screen_size_x(s) - 1)
 		return;

-#ifdef ENABLE_SIXEL
-	if (image_check_line(s, s->cy, 1) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	image_redraw_area(ctx, 0, s->cy, screen_size_x(s), 1);
 #endif

 	screen_write_initctx(ctx, &ttyctx, 0, 1);
@@ -1437,9 +1474,8 @@ screen_write_clearcharacter(struct screen_write_ctx *ctx, u_int nx, u_int bg)
 	if (s->cx > screen_size_x(s) - 1)
 		return;

-#ifdef ENABLE_SIXEL
-	if (image_check_line(s, s->cy, 1) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	image_redraw_area(ctx, 0, s->cy, screen_size_x(s), 1);
 #endif

 	screen_write_initctx(ctx, &ttyctx, 0, 1);
@@ -1472,11 +1508,6 @@ screen_write_insertline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 	if (ny == 0)
 		ny = 1;

-#ifdef ENABLE_SIXEL
-	if (image_check_line(s, s->cy, sy - s->cy) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
-#endif
-
 	if (s->cy < s->rupper || s->cy > s->rlower) {
 		if (ny > sy - s->cy)
 			ny = sy - s->cy;
@@ -1498,7 +1529,7 @@ screen_write_insertline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 			return;
 		}

-		screen_write_redraw_pane(ctx, &ttyctx);
+		screen_write_redraw_pane(ctx);
 		return;
 	}

@@ -1525,7 +1556,7 @@ screen_write_insertline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 		return;
 	}

-	screen_write_redraw_pane(ctx, &ttyctx);
+	screen_write_redraw_pane(ctx);
 }

 /* Delete ny lines. */
@@ -1540,11 +1571,6 @@ screen_write_deleteline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 	if (ny == 0)
 		ny = 1;

-#ifdef ENABLE_SIXEL
-	if (image_check_line(s, s->cy, sy - s->cy) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
-#endif
-
 	if (s->cy < s->rupper || s->cy > s->rlower) {
 		if (ny > sy - s->cy)
 			ny = sy - s->cy;
@@ -1567,7 +1593,7 @@ screen_write_deleteline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 			return;
 		}

-		screen_write_redraw_pane(ctx, &ttyctx);
+		screen_write_redraw_pane(ctx);
 		return;
 	}

@@ -1595,7 +1621,7 @@ screen_write_deleteline(struct screen_write_ctx *ctx, u_int ny, u_int bg)
 		return;
 	}

-	screen_write_redraw_pane(ctx, &ttyctx);
+	screen_write_redraw_pane(ctx);
 }

 /* Clear line at cursor. */
@@ -1613,9 +1639,8 @@ screen_write_clearline(struct screen_write_ctx *ctx, u_int bg)
 	if (gl->cellsize == 0 && COLOUR_DEFAULT(bg))
 		return;

-#ifdef ENABLE_SIXEL
-	if (image_check_line(s, s->cy, 1) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	image_redraw_area(ctx, 0, s->cy, screen_size_x(s), 1);
 #endif

 	flags = gl->flags & GRID_LINE_OSC133_FLAGS;
@@ -1652,9 +1677,8 @@ screen_write_clearendofline(struct screen_write_ctx *ctx, u_int bg)
 	if (s->cx > sx - 1 || (s->cx >= gl->cellsize && COLOUR_DEFAULT(bg)))
 		return;

-#ifdef ENABLE_SIXEL
-	if (image_check_line(s, s->cy, 1) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	image_redraw_area(ctx, 0, s->cy, screen_size_x(s), 1);
 #endif

 	grid_view_clear(s->grid, s->cx, s->cy, sx - s->cx, 1, bg);
@@ -1679,9 +1703,8 @@ screen_write_clearstartofline(struct screen_write_ctx *ctx, u_int bg)
 		return;
 	}

-#ifdef ENABLE_SIXEL
-	if (image_check_line(s, s->cy, 1) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	image_redraw_area(ctx, 0, s->cy, screen_size_x(s), 1);
 #endif

 	if (s->cx > sx - 1)
@@ -1726,6 +1749,9 @@ screen_write_reverseindex(struct screen_write_ctx *ctx, u_int bg)
 	struct screen	*s = ctx->s;
 	struct tty_ctx	 ttyctx;
 	u_int		 ry;
+#ifdef ENABLE_IMAGES
+	int		 image_scroll;
+#endif

 	if (s->cy != s->rupper) {
 		if (s->cy > 0)
@@ -1733,16 +1759,20 @@ screen_write_reverseindex(struct screen_write_ctx *ctx, u_int bg)
 		return;
 	}

-#ifdef ENABLE_SIXEL
-	if (image_free_all(s) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	image_scroll = image_grid_check_area(s->grid, 0,
+	    s->grid->hsize + s->rupper, screen_size_x(s),
+	    s->rlower - s->rupper + 1);
 #endif
-
 	grid_view_scroll_region_down(s->grid, s->rupper, s->rlower, bg);
 	screen_write_collect_flush(ctx, 0, __func__);

 	screen_write_initctx(ctx, &ttyctx, 1, 1);
 	ttyctx.bg = bg;
+#ifdef ENABLE_IMAGES
+	if (image_scroll)
+		ttyctx.flags |= TTY_CTX_IMAGE_SCROLL;
+#endif

 	ry = s->rlower + 1 - s->rupper;
 	if (!screen_write_should_draw_lines(ctx, s->rupper, ry))
@@ -1752,7 +1782,7 @@ screen_write_reverseindex(struct screen_write_ctx *ctx, u_int bg)
 		return;
 	}

-	screen_write_redraw_pane(ctx, &ttyctx);
+	screen_write_redraw_pane(ctx);
 }

 /* Set scroll region. */
@@ -1785,9 +1815,6 @@ screen_write_linefeed(struct screen_write_ctx *ctx, int wrapped, u_int bg)
 	struct screen		*s = ctx->s;
 	struct grid		*gd = s->grid;
 	struct grid_line	*gl;
-#ifdef ENABLE_SIXEL
-	int			 redraw = 0;
-#endif
 	u_int			 rupper = s->rupper, rlower = s->rlower;

 	gl = grid_get_line(gd, gd->hsize + s->cy);
@@ -1808,13 +1835,10 @@ screen_write_linefeed(struct screen_write_ctx *ctx, int wrapped, u_int bg)
 		return;
 	}

-#ifdef ENABLE_SIXEL
-	if (rlower == screen_size_y(s) - 1)
-		redraw = image_scroll_up(s, 1);
-	else
-		redraw = image_check_line(s, rupper, rlower - rupper);
-	if (redraw && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	if (image_grid_check_area(gd, 0, gd->hsize + rupper,
+	    screen_size_x(s), rlower - rupper + 1))
+		ctx->scrolled_images = 1;
 #endif

 	grid_view_scroll_region_up(gd, s->rupper, s->rlower, bg);
@@ -1840,9 +1864,10 @@ screen_write_scrollup(struct screen_write_ctx *ctx, u_int lines, u_int bg)
 		ctx->bg = bg;
 	}

-#ifdef ENABLE_SIXEL
-	if (image_scroll_up(s, lines) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	if (image_grid_check_area(gd, 0, gd->hsize + s->rupper,
+	    screen_size_x(s), s->rlower - s->rupper + 1))
+		ctx->scrolled_images = 1;
 #endif

 	for (i = 0; i < lines; i++) {
@@ -1869,9 +1894,10 @@ screen_write_scrolldown(struct screen_write_ctx *ctx, u_int lines, u_int bg)
 	else if (lines > s->rlower - s->rupper + 1)
 		lines = s->rlower - s->rupper + 1;

-#ifdef ENABLE_SIXEL
-	if (image_free_all(s) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	if (image_grid_check_area(gd, 0, gd->hsize + s->rupper,
+	    screen_size_x(s), s->rlower - s->rupper + 1))
+		ttyctx.flags |= TTY_CTX_IMAGE_SCROLL;
 #endif

 	for (i = 0; i < lines; i++)
@@ -1888,7 +1914,7 @@ screen_write_scrolldown(struct screen_write_ctx *ctx, u_int lines, u_int bg)
 		return;
 	}

-	screen_write_redraw_pane(ctx, &ttyctx);
+	screen_write_redraw_pane(ctx);
 }

 /* Carriage return (cursor to start of line). */
@@ -1910,9 +1936,8 @@ screen_write_clearendofscreen(struct screen_write_ctx *ctx, u_int bg)
 	struct visible_ranges	*r;
 	struct visible_range	*ri;

-#ifdef ENABLE_SIXEL
-	if (image_check_line(s, s->cy, sy - s->cy) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	image_redraw_area(ctx, 0, s->cy, screen_size_x(s), sy - s->cy);
 #endif

 	screen_write_initctx(ctx, &ttyctx, 1, 1);
@@ -1991,9 +2016,8 @@ screen_write_clearstartofscreen(struct screen_write_ctx *ctx, u_int bg)
 	struct visible_ranges	*r;
 	struct visible_range	*ri;

-#ifdef ENABLE_SIXEL
-	if (image_check_line(s, 0, s->cy - 1) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	image_redraw_area(ctx, 0, 0, screen_size_x(s), s->cy + 1);
 #endif

 	screen_write_initctx(ctx, &ttyctx, 1, 1);
@@ -2064,9 +2088,8 @@ screen_write_clearscreen(struct screen_write_ctx *ctx, u_int bg)
 	struct visible_ranges	*r;
 	struct visible_range	*ri;

-#ifdef ENABLE_SIXEL
-	if (image_free_all(s) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	image_redraw_all(ctx);
 #endif

 	screen_write_initctx(ctx, &ttyctx, 1, 1);
@@ -2274,7 +2297,7 @@ screen_write_collect_flush_scrolled(struct screen_write_ctx *ctx)

 	screen_write_initctx(ctx, &ttyctx, 1, 1);
 	if (ttyctx.flags & TTY_CTX_PANE_OBSCURED && wp != NULL) {
-		screen_write_redraw_pane(ctx, &ttyctx);
+		screen_write_redraw_pane(ctx);
 		return 0;
 	}
 	if (wp != NULL && window_pane_scrollbar_overlay_visible(wp)) {
@@ -2291,6 +2314,10 @@ screen_write_collect_flush_scrolled(struct screen_write_ctx *ctx)
 		ttyctx.orlower -= (wp->yoff + wp->sy - wp->window->sy);
 	ttyctx.n = ctx->scrolled;
 	ttyctx.bg = ctx->bg;
+#ifdef ENABLE_IMAGES
+	if (ctx->scrolled_images)
+		ttyctx.flags |= TTY_CTX_IMAGE_SCROLL;
+#endif
 	tty_write(tty_cmd_scrollup, &ttyctx);

 	if (wp != NULL)
@@ -2420,6 +2447,9 @@ screen_write_collect_flush(struct screen_write_ctx *ctx, int scroll_only,
 		if (!screen_write_collect_flush_scrolled(ctx))
 			goto discard;
 		ctx->scrolled = 0;
+#ifdef ENABLE_IMAGES
+		ctx->scrolled_images = 0;
+#endif
 	}
 	ctx->bg = 8;

@@ -2443,6 +2473,9 @@ discard:
 		}
 	}
 	ctx->scrolled = 0;
+#ifdef ENABLE_IMAGES
+	ctx->scrolled_images = 0;
+#endif
 	ctx->bg = 8;
 }

@@ -2569,9 +2602,8 @@ screen_write_collect_end(struct screen_write_ctx *ctx)
 		}
 	}

-#ifdef ENABLE_SIXEL
-	if (image_check_area(s, s->cx, s->cy, ci->used, 1) && ctx->wp != NULL)
-		ctx->wp->flags |= PANE_REDRAW;
+#ifdef ENABLE_IMAGES
+	screen_write_image_damage(ctx, s->cx, s->cy, ci->used, 1);
 #endif

 	grid_view_set_cells(s->grid, s->cx, s->cy, &ci->gc, cl->data + ci->x,
@@ -2661,6 +2693,9 @@ screen_write_cell(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 	u_int			 sx = screen_size_x(s), sy = screen_size_y(s);
 	u_int			 width = ud->width, xx, not_wrap, i, n, vis;
 	int			 selected, skip = 1, redraw = 0;
+#ifdef ENABLE_IMAGES
+	int			 selection_image = 0;
+#endif
 	int			 yoff = 0, xoff = 0;
 	struct visible_ranges	*r;
 	struct visible_range	*ri;
@@ -2701,6 +2736,12 @@ screen_write_cell(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 		return;
 	screen_write_initctx(ctx, &ttyctx, 0, 0);

+#ifdef ENABLE_IMAGES
+	/* Input semantics decide which image layers this text damages. */
+	if (screen_write_image_damage(ctx, s->cx, s->cy, width, 1))
+		skip = 0;
+#endif
+
 	/* Handle overwriting of UTF-8 characters. */
 	gl = grid_get_line(s->grid, s->grid->hsize + s->cy);
 	if (gl->flags & GRID_LINE_EXTENDED) {
@@ -2748,6 +2789,14 @@ screen_write_cell(struct screen_write_ctx *ctx, const struct grid_cell *gc)

 	/* Update the selected flag and set the cell. */
 	selected = screen_check_selection(s, s->cx, s->cy);
+#ifdef ENABLE_IMAGES
+	/* Selection highlighting must not overwrite image-covered cells. */
+	if (selected && image_grid_check_area(gd, s->cx,
+	    gd->hsize + s->cy, width, 1)) {
+		selected = 0;
+		selection_image = 1;
+	}
+#endif
 	if (selected && (~gc->flags & GRID_FLAG_SELECTED)) {
 		memcpy(&tmp_gc, gc, sizeof tmp_gc);
 		tmp_gc.flags |= GRID_FLAG_SELECTED;
@@ -2758,6 +2807,11 @@ screen_write_cell(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 		grid_view_set_cell(gd, s->cx, s->cy, &tmp_gc);
 	} else if (!skip)
 		grid_view_set_cell(gd, s->cx, s->cy, gc);
+#ifdef ENABLE_IMAGES
+	if (selection_image)
+		skip = 1;
+	else
+#endif
 	if (selected)
 		skip = 0;

@@ -2927,6 +2981,9 @@ screen_write_combine(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 		force_wide = 0;

 	/* Set the new cell. */
+#ifdef ENABLE_IMAGES
+	screen_write_image_damage(ctx, cx - n, cy, n, 1);
+#endif
 	grid_view_set_cell(gd, cx - n, cy, &last);
 	if (force_wide)
 		grid_view_set_padding(gd, cx - 1, cy, last.bg);
@@ -3060,63 +3117,21 @@ screen_write_rawstring(struct screen_write_ctx *ctx, u_char *str, u_int len,
 	tty_write(tty_cmd_rawstring, &ttyctx);
 }

-#ifdef ENABLE_SIXEL
+#ifdef ENABLE_IMAGES
 /* Write a SIXEL image. */
 void
 screen_write_sixelimage(struct screen_write_ctx *ctx, struct sixel_image *si,
    u_int bg)
 {
-	struct screen		*s = ctx->s;
-	struct grid		*gd = s->grid;
-	struct tty_ctx		 ttyctx;
-	u_int			 x, y, sx, sy, cx = s->cx, cy = s->cy, i, lines;
-	struct sixel_image	*new;
+	struct image	*im;

-	if (screen_size_y(s) == 1)
-		return;
-
-	sixel_size_in_cells(si, &x, &y);
-	if (x > screen_size_x(s) || y > screen_size_y(s) - 1) {
-		if (x > screen_size_x(s) - cx)
-			sx = screen_size_x(s) - cx;
-		else
-			sx = x;
-		if (y > screen_size_y(s) - 1)
-			sy = screen_size_y(s) - 1;
-		else
-			sy = y;
-		new = sixel_scale(si, 0, 0, 0, y - sy, sx, sy, 1);
+	im = sixel_to_image(si);
+	if (im == NULL) {
 		sixel_free(si);
-		if (new == NULL)
-			return;
-		sixel_size_in_cells(new, &x, &y);
-		si = new;
+		return;
 	}
-
-	sy = screen_size_y(s) - cy;
-	if (sy <= y) {
-		lines = y - sy + 1;
-		if (image_scroll_up(s, lines) && ctx->wp != NULL)
-			ctx->wp->flags |= PANE_REDRAW;
-		for (i = 0; i < lines; i++) {
-			grid_view_scroll_region_up(gd, 0, screen_size_y(s) - 1,
-			    bg);
-			screen_write_collect_scroll(ctx, bg);
-		}
-		ctx->scrolled += lines;
-		if (lines > cy)
-			screen_write_cursormove(ctx, -1, 0, 0);
-		else
-			screen_write_cursormove(ctx, -1, cy - lines, 0);
-	}
-	screen_write_collect_flush(ctx, 0, __func__);
-
-	screen_write_initctx(ctx, &ttyctx, 0, 0);
-	ttyctx.image = image_store(s, si);
-
-	tty_write(tty_cmd_sixelimage, &ttyctx);
-
-	screen_write_cursormove(ctx, 0, cy + y, 0);
+	image_write_sixel(ctx, im, bg);
+	image_free(image_get_id(im));
 }
 #endif

--- a/screen.c
+++ b/screen.c
@@ -93,11 +93,6 @@ screen_init(struct screen *s, u_int sx, u_int sy, u_int hlimit)
 	s->tabs = NULL;
 	s->sel = NULL;

-#ifdef ENABLE_SIXEL
-	TAILQ_INIT(&s->images);
-	TAILQ_INIT(&s->saved_images);
-#endif
-
 	s->write_list = NULL;
 	s->hyperlinks = NULL;

@@ -131,11 +126,6 @@ screen_reinit(struct screen *s, int check)

 	screen_clear_selection(s);
 	screen_free_titles(s);
-
-#ifdef ENABLE_SIXEL
-	image_free_all(s);
-#endif
-
 	screen_set_progress_bar(s, PROGRESS_BAR_HIDDEN, 0);
 	screen_reset_hyperlinks(s);
 }
@@ -154,10 +144,6 @@ screen_reset_hyperlinks(struct screen *s)
 void
 screen_free(struct screen *s)
 {
-#ifdef ENABLE_SIXEL
-	struct image	*im;
-#endif
-
 	free(s->sel);
 	free(s->tabs);
 	free(s->path);
@@ -174,17 +160,6 @@ screen_free(struct screen *s)
 		hyperlinks_free(s->hyperlinks);
 	screen_free_titles(s);

-#ifdef ENABLE_SIXEL
-	/*
-	 * Images saved when entering the alternate screen stay linked in the
-	 * global list; move them back so they are freed and unlinked here, or
-	 * a later eviction would write through this freed screen.
-	 */
-	TAILQ_CONCAT(&s->images, &s->saved_images, entry);
-	TAILQ_FOREACH(im, &s->images, entry)
-		im->list = &s->images;
-	image_free_all(s);
-#endif
 }

 /* Reset tabs to default, eight spaces apart. */
@@ -377,10 +352,6 @@ screen_resize_cursor(struct screen *s, u_int sx, u_int sy, int reflow,
 	if (sy != screen_size_y(s))
 		screen_resize_y(s, sy, eat_empty, &cy);

-#ifdef ENABLE_SIXEL
-	image_free_all(s);
-#endif
-
 	if (reflow)
 		screen_reflow(s, sx, &cx, &cy, cursor);

@@ -692,10 +663,6 @@ int
 screen_alternate_on(struct screen *s, struct grid_cell *gc, int cursor)
 {
 	u_int		 sx, sy;
-#ifdef ENABLE_SIXEL
-	struct image	*im;
-#endif
-
 	if (SCREEN_IS_ALTERNATE(s))
 		return 0;
 	sx = screen_size_x(s);
@@ -709,12 +676,6 @@ screen_alternate_on(struct screen *s, struct grid_cell *gc, int cursor)
 	}
 	memcpy(&s->saved_cell, gc, sizeof s->saved_cell);

-#ifdef ENABLE_SIXEL
-	TAILQ_CONCAT(&s->saved_images, &s->images, entry);
-	TAILQ_FOREACH(im, &s->saved_images, entry)
-	    im->list = &s->saved_images;
-#endif
-
 	grid_view_clear(s->grid, 0, 0, sx, sy, 8);

 	s->saved_flags = s->grid->flags;
@@ -728,10 +689,6 @@ int
 screen_alternate_off(struct screen *s, struct grid_cell *gc, int cursor)
 {
 	u_int		 sx = screen_size_x(s), sy = screen_size_y(s);
-#ifdef ENABLE_SIXEL
-	struct image	*im;
-#endif
-
 	/*
 	 * If the current size is different, temporarily resize to the old size
 	 * before copying back.
@@ -774,13 +731,6 @@ screen_alternate_off(struct screen *s, struct grid_cell *gc, int cursor)
 	grid_destroy(s->saved_grid);
 	s->saved_grid = NULL;

-#ifdef ENABLE_SIXEL
-	image_free_all(s);
-	TAILQ_CONCAT(&s->images, &s->saved_images, entry);
-	TAILQ_FOREACH(im, &s->images, entry)
-	    im->list = &s->images;
-#endif
-
 	if (s->cx > screen_size_x(s) - 1)
 		s->cx = screen_size_x(s) - 1;
 	if (s->cy > screen_size_y(s) - 1)
--- a/server-client.c
+++ b/server-client.c
@@ -2441,18 +2441,19 @@ server_client_check_redraw(struct client *c)

 	if (c->flags & (CLIENT_CONTROL|CLIENT_SUSPENDED))
 		return;
-	if (c->flags & CLIENT_ALLREDRAWFLAGS) {
-		log_debug("%s: redraw%s%s%s%s%s", c->name,
+	if (c->flags & (CLIENT_ALLREDRAWFLAGS|CLIENT_REDRAWSCROLLBARS)) {
+		log_debug("%s: redraw%s%s%s%s%s%s", c->name,
 		    (c->flags & CLIENT_REDRAWWINDOW) ? " window" : "",
 		    (c->flags & CLIENT_REDRAWSTATUS) ? " status" : "",
 		    (c->flags & CLIENT_REDRAWBORDERS) ? " borders" : "",
 		    (c->flags & CLIENT_REDRAWOVERLAY) ? " overlay" : "",
-		    (c->flags & CLIENT_REDRAWMENU) ? " menu" : "");
+		    (c->flags & CLIENT_REDRAWMENU) ? " menu" : "",
+		    (c->flags & CLIENT_REDRAWSCROLLBARS) ? " scrollbars" : "");
 	}

 	/* Work out if a redraw is actually needed. */
 	needed = 0;
-	if (c->flags & CLIENT_ALLREDRAWFLAGS)
+	if (c->flags & (CLIENT_ALLREDRAWFLAGS|CLIENT_REDRAWSCROLLBARS))
 		needed = 1;
 	else if (server_client_any_pane_redraw(c))
 		needed = 1;
@@ -2478,8 +2479,14 @@ server_client_check_redraw(struct client *c)
 			log_debug("redraw timer started");
 			evtimer_add(&ev, &tv);
 		}
-		if (server_client_any_pane_redraw(c))
-			c->flags |= CLIENT_REDRAWWINDOW;
+		TAILQ_FOREACH(wp, &w->panes, entry) {
+			if (wp->flags & PANE_REDRAW) {
+				c->flags |= CLIENT_REDRAWWINDOW;
+				break;
+			}
+			if (wp->flags & PANE_REDRAWSCROLLBAR)
+				c->flags |= CLIENT_REDRAWSCROLLBARS;
+		}
 		return;
 	}

@@ -2498,7 +2505,8 @@ server_client_check_redraw(struct client *c)
 				log_debug("%s: redraw pane %%%u", __func__,
 				    wp->id);
 				redraw_pane(c, wp);
-			} else if (wp->flags & PANE_REDRAWSCROLLBAR) {
+			} else if ((wp->flags & PANE_REDRAWSCROLLBAR) ||
+			    (c->flags & CLIENT_REDRAWSCROLLBARS)) {
 				log_debug("%s: redraw scrollbar %%%u", __func__,
 				    wp->id);
 				redraw_pane_scrollbar(c, wp);
@@ -2528,7 +2536,8 @@ server_client_check_redraw(struct client *c)
 	 * All the redraw flags can now be cleared. Also record how many bytes
 	 * were written.
 	 */
-	c->flags &= ~(CLIENT_ALLREDRAWFLAGS|CLIENT_STATUSFORCE);
+	c->flags &= ~(CLIENT_ALLREDRAWFLAGS|CLIENT_REDRAWSCROLLBARS|
+	    CLIENT_STATUSFORCE);
 	c->redraw = EVBUFFER_LENGTH(tty->out);
 	log_debug("%s: redraw added %zu bytes", c->name, c->redraw);
 }
--- a/style.c
+++ b/style.c
@@ -30,7 +30,8 @@

 /* Default style. */
 static struct style style_default = {
-	{ { { ' ' }, 0, 1, 1 }, 0, 0, 8, 8, 0, 0 },
+	{ { { ' ' }, 0, 1, 1 }, 0, 0, 8, 8, 0, 0
+	},
 	0,
 	0,

--- a/tmux.1
+++ b/tmux.1
@@ -5073,6 +5073,10 @@ Ignore function keys from
 and use the
 .Nm
 internal set only.
+.It kitty
+Supports Kitty graphics using Unicode placeholders.
+The terminal must support the Kitty Unicode placeholder extension, not only
+the basic Kitty graphics protocol.
 .It margins
 Supports DECSLRM margins.
 .It mouse
--- a/tmux.h
+++ b/tmux.h
@@ -75,7 +75,12 @@ struct screen_write_cline;
 struct screen_write_ctx;
 struct session;

-#ifdef ENABLE_SIXEL
+#ifdef ENABLE_IMAGES
+struct image;
+struct image_backend;
+struct image_rect;
+struct image_line;
+struct image_store;
 struct sixel_image;
 #endif

@@ -858,7 +863,7 @@ struct colour_palette {
 struct grid_cell {
 	struct utf8_data	data;
 	u_short			attr;
-	u_char			flags;
+	u_short			flags;
 	int			fg;
 	int			bg;
 	int			us;
@@ -869,7 +874,7 @@ struct grid_cell {
 struct grid_extd_entry {
 	utf8_char		data;
 	u_short			attr;
-	u_char			flags;
+	u_short			flags;
 	int			fg;
 	int			bg;
 	int			us;
@@ -887,7 +892,7 @@ struct grid_cell_entry {
 			u_char	data;
 		} data;
 	};
-	u_char			flags;
+	u_short			flags;
 } __packed;

 /* OSC 133 data for a grid line. */
@@ -911,6 +916,9 @@ struct grid_line {
 	u_int			 time;
 	struct osc133_data	 osc133_data;
 	u_short			 flags;
+#ifdef ENABLE_IMAGES
+	struct image_line	*images;
+#endif
 };

 /* Entire grid of cells. */
@@ -930,6 +938,9 @@ struct grid {
 	u_int			 scroll_generation;

 	struct grid_line	*linedata;
+#ifdef ENABLE_IMAGES
+	struct image_store	*images;
+#endif
 };

 /* Virtual cursor in a grid. */
@@ -1021,24 +1032,8 @@ struct style {
 	u_int			link;
 };

-#ifdef ENABLE_SIXEL
-/* Image. */
-struct image {
-	struct screen		*s;
-	struct sixel_image	*data;
-	char			*fallback;
-
-	u_int			 px;
-	u_int			 py;
-	u_int			 sx;
-	u_int			 sy;
-
-	struct images		*list;
-	TAILQ_ENTRY (image)	 entry;
-
-	TAILQ_ENTRY (image)	 all_entry;
-};
-TAILQ_HEAD(images, image);
+#ifdef ENABLE_IMAGES
+#define IMAGE_SIZE_LIMIT (64 * 1024 * 1024)
 #endif

 /* Cursor style. */
@@ -1097,11 +1092,6 @@ struct screen {
 	bitstr_t			*tabs;
 	struct screen_sel		*sel;

-#ifdef ENABLE_SIXEL
-	struct images			 images;
-	struct images			 saved_images;
-#endif
-
 	struct screen_write_cline	*write_list;

 	struct hyperlinks		*hyperlinks;
@@ -1119,12 +1109,16 @@ struct screen_write_ctx {
 #define SCREEN_WRITE_SYNC 0x1
 #define SCREEN_WRITE_OBSCURED 0x2
 #define SCREEN_WRITE_CHECKED_IF_OBSCURED 0x4
+#define SCREEN_WRITE_INPUT 0x8

 	screen_write_init_ctx_cb	 init_ctx_cb;
 	void				*arg;

 	struct screen_write_citem	*item;
 	u_int				 scrolled;
+#ifdef ENABLE_IMAGES
+	int				 scrolled_images;
+#endif
 	u_int				 bg;
 };

@@ -1731,7 +1725,8 @@ struct tty_term {
 #define TERM_RGBCOLOURS 0x10
 #define TERM_VT100LIKE 0x20
 #define TERM_SIXEL 0x40
-#define TERM_INVALIDMS 0x80
+#define TERM_KITTY 0x80
+#define TERM_INVALIDMS 0x100
 	int		 flags;

 	LIST_ENTRY(tty_term) entry;
@@ -1833,6 +1828,10 @@ struct tty {

 	struct event	 key_timer;
 	struct tty_key	*key_tree;
+#ifdef ENABLE_IMAGES
+	const struct image_backend *image_backend;
+	void		*image_data;
+#endif
 };

 /* Terminal command context. */
@@ -1854,6 +1853,8 @@ struct tty_ctx {
 #define TTY_CTX_OVERLAY_SYNC 0x10
 #define TTY_CTX_CELL_INVALIDATE 0x20
 #define TTY_CTX_PANE_OBSCURED 0x40
+#define TTY_CTX_IMAGE_SCROLL 0x80
+#define TTY_CTX_PANE_FULL_WIDTH 0x100

 	union {
 		u_int			 n;
@@ -1869,7 +1870,7 @@ struct tty_ctx {
 			size_t		 size;
 		} sel;

-#ifdef ENABLE_SIXEL
+#ifdef ENABLE_IMAGES
 		struct image		*image;
 #endif
 	};
@@ -2287,7 +2288,7 @@ struct client {
 #define CLIENT_STARTSERVER 0x10000000
 #define CLIENT_REDRAWMENU 0x20000000
 #define CLIENT_NOFORK 0x40000000
-/* 0x80000000ULL unused */
+#define CLIENT_REDRAWSCROLLBARS 0x80000000ULL
 #define CLIENT_CONTROL_PAUSEAFTER 0x100000000ULL
 #define CLIENT_CONTROL_WAITEXIT 0x200000000ULL
 #define CLIENT_WINDOWSIZECHANGED 0x400000000ULL
@@ -2988,10 +2989,6 @@ void	tty_cmd_scrolldown(struct tty *, const struct tty_ctx *);
 void	tty_cmd_reverseindex(struct tty *, const struct tty_ctx *);
 void	tty_cmd_setselection(struct tty *, const struct tty_ctx *);
 void	tty_cmd_rawstring(struct tty *, const struct tty_ctx *);
-#ifdef ENABLE_SIXEL
-void	tty_cmd_sixelimage(struct tty *, const struct tty_ctx *);
-void	tty_draw_images(struct client *, struct window_pane *);
-#endif
 void	tty_cmd_syncstart(struct tty *, const struct tty_ctx *);
 void	tty_default_colours(struct grid_cell *, struct window_pane *, u_int *);

@@ -3634,7 +3631,7 @@ void	 screen_write_setselection(struct screen_write_ctx *, const char *,
 	     u_char *, u_int);
 void	 screen_write_rawstring(struct screen_write_ctx *, u_char *, u_int,
 	     int);
-#ifdef ENABLE_SIXEL
+#ifdef ENABLE_IMAGES
 void	 screen_write_sixelimage(struct screen_write_ctx *,
 	     struct sixel_image *, u_int);
 #endif
@@ -4220,17 +4217,106 @@ void		 spawn_editor_finish(struct window_pane *);
 /* regsub.c */
 char		*regsub(const char *, const char *, const char *, int);

-#ifdef ENABLE_SIXEL
+#ifdef ENABLE_IMAGES
 /* image.c */
-int		 image_free_all(struct screen *);
-struct image	*image_store(struct screen *, struct sixel_image *);
-int		 image_check_line(struct screen *, u_int, u_int);
-int		 image_check_area(struct screen *, u_int, u_int, u_int, u_int);
-int		 image_scroll_up(struct screen *, u_int);
+#define IMAGE_BACKEND_GRAPHICAL 0x1
+#define IMAGE_BACKEND_SCROLLS   0x2

+struct image	*image_create(u_int, u_int, u_int, u_int, u_int, u_int,
+		     u_char *);
+struct image	*image_create_view(struct image *, u_int, u_int, u_int,
+		     u_int, u_int, u_int, u_int, u_int, u_int, u_int);
+struct image	*image_find(u_int);
+u_int		 image_get_id(const struct image *);
+void		 image_get_size(const struct image *, u_int *, u_int *);
+void		 image_get_canvas_size(const struct image *, u_int *, u_int *);
+void		 image_get_size_in_cells(const struct image *, u_int *, u_int *);
+const u_char	*image_get_pixels(const struct image *, size_t *, size_t *);
+void		 image_set_no_cursor(struct image *);
+struct sixel_image *image_get_sixel(const struct image *);
+void		 image_set_sixel(struct image *, struct sixel_image *);
+void		 image_ref(u_int);
+void		 image_free(u_int);
+void		 image_write_sixel(struct screen_write_ctx *, struct image *,
+		     u_int);
+void		 image_write_kitty(struct screen_write_ctx *, struct image *,
+		     u_int, u_int, u_int, int32_t);
+void		 image_get_pixel_rect(const struct image *, u_int, u_int,
+		     u_int, u_int, u_int *, u_int *, u_int *, u_int *);
+void		 image_size_in_cells(u_int, u_int, u_int, u_int, u_int *,
+		     u_int *);
+u_char		*image_base64_decode(const char *, size_t, size_t, size_t *);
+u_char		*image_png_decode(const u_char *, size_t, size_t, u_int *,
+		     u_int *);
+void		 image_redraw_area(struct screen_write_ctx *, u_int, u_int,
+		     u_int, u_int);
+void		 image_redraw_all(struct screen_write_ctx *);
+void		 image_redraw_start(struct tty *, u_int, u_int, u_int, u_int);
+int		 image_backend_flags(struct tty *);
+void		 image_tty_update(struct tty *);
+void		 image_tty_geometry_changed(struct tty *);
+void		 image_tty_free(struct tty *, int);
+void		 image_draw_line(struct tty *, struct screen *, u_int, u_int,
+		     u_int, u_int, u_int, int, const struct tty_style_ctx *);
+void		 image_draw_after_text(struct tty *, struct screen *, u_int,
+		     u_int, u_int, u_int, u_int, const struct tty_style_ctx *);
+void		 image_get_fallback_cell(struct tty *, struct image *, u_int,
+		     u_int, const struct grid_cell *, struct grid_cell *,
+		     const struct tty_style_ctx *);
+int		 image_get_fallback_at(struct tty *, struct screen *, u_int,
+		     u_int, const struct grid_cell *, struct grid_cell *,
+		     const struct tty_style_ctx *);
+struct image	*image_rect_get_image(const struct image_rect *);
+const struct grid_cell *image_rect_get_cell(
+			     const struct image_rect *);
+void		 image_rect_get_coords(const struct image_rect *,
+		     u_int *, u_int *, u_int *, u_int *, u_int *, u_int *);
+int32_t		 image_rect_get_z(const struct image_rect *);
+void		 image_clear(struct screen_write_ctx *, u_int);
+void		 image_clear_kitty(struct screen_write_ctx *, char, u_int,
+		     u_int, int32_t);
+void		 image_grid_damage(struct grid *, u_int, u_int, u_int, u_int);
+void		 image_grid_free_line(struct grid *, struct grid_line *);
+void		 image_grid_free(struct grid *);
+void		 image_grid_move_cells(struct grid *, u_int, u_int, u_int,
+		     u_int);
+void		 image_grid_duplicate_lines(struct grid *, u_int, struct grid *,
+		     u_int, u_int);
+void		 image_grid_copy_area(struct grid *, u_int, u_int, struct grid *,
+		     u_int, u_int, u_int, u_int);
+int		 image_grid_line_has_images(const struct grid_line *);
+int		 image_grid_check_area(struct grid *, u_int, u_int, u_int,
+		     u_int);
+int		 image_grid_get_source(struct grid *, u_int, u_int,
+		     struct image *, u_int *, u_int *);
+void		 image_place_cell_kitty(struct screen_write_ctx *, struct image *,
+		     u_int, u_int, u_int, u_int, u_int, u_int, int32_t);
+#define KITTY_PARSE_ERROR -1
+#define KITTY_PARSE_OK 0
+#define KITTY_PARSE_MORE 1
+#define KITTY_PARSE_MISSING 2
+struct image	*kitty_parse_image(void **, const u_char *, size_t, u_int,
+		     u_int, u_int *, u_int *, u_int *, char *, char *, u_int *,
+		     int32_t *, int *);
+int		 kitty_placeholder_to_image(void *, struct grid *,
+		     struct grid_cell *, u_int, u_int, struct image **, u_int *,
+		     u_int *, u_int *, u_int *, int32_t *);
+void		 kitty_free_state(void *);
+void		 kitty_draw_rect(struct tty *,
+			     const struct image_rect *, const struct tty_style_ctx *);
+void		 kitty_redraw_start(struct tty *, u_int, u_int, u_int, u_int);
+void		 kitty_free_output_state(struct tty *, int);
+#endif
+
+#ifdef ENABLE_IMAGES
 /* image-sixel.c */
 #define SIXEL_COLOUR_REGISTERS 1024
-struct sixel_image *sixel_parse(const char *, size_t, u_int, u_int, u_int);
+void		 sixel_draw_rect(struct tty *,
+		     const struct image_rect *, const struct tty_style_ctx *);
+void		 sixel_redraw_start(struct tty *, u_int, u_int, u_int, u_int);
+void		 sixel_free_output(struct tty *, int);
+struct sixel_image *sixel_parse(const char *, size_t, u_int, u_int, u_int,
+    u_int);
 void		 sixel_free(struct sixel_image *);
 void		 sixel_log(struct sixel_image *);
 void		 sixel_size_in_cells(struct sixel_image *, u_int *, u_int *);
@@ -4239,6 +4325,7 @@ struct sixel_image *sixel_scale(struct sixel_image *, u_int, u_int, u_int,
 char		*sixel_print(struct sixel_image *, struct sixel_image *,
 		     size_t *);
 struct screen	*sixel_to_screen(struct sixel_image *);
+struct image	*sixel_to_image(struct sixel_image *);
 #endif

 /* server-acl.c */
--- a/tools/generate-image-diacritics.sh
+++ b/tools/generate-image-diacritics.sh
@@ -0,0 +1,51 @@
+#!/bin/sh
+
+# Generate the Unicode diacritic table used by Kitty image placeholders.
+#
+# Input must be UnicodeData.txt from Unicode 6.0.0:
+# https://www.unicode.org/Public/6.0.0/ucd/UnicodeData.txt
+# SHA-256: 90b45b777346bef027556f9c6cb3ea5d7d745bd60d6762855c08d8a22d34f771
+#
+# The selection follows the public Kitty graphics protocol: nonspacing marks
+# with canonical combining class 230, NSM bidi class, no decomposition, minus
+# characters which may be combined or normalized in ways unsuitable for a
+# row or column index.
+
+if [ "$#" -ne 1 ]; then
+	echo "usage: $0 UnicodeData.txt" >&2
+	exit 1
+fi
+
+awk -F ';' '
+BEGIN {
+	omit["0300"] = omit["0301"] = omit["0302"] = 1
+	omit["0303"] = omit["0304"] = omit["0306"] = 1
+	omit["0307"] = omit["0308"] = omit["0309"] = 1
+	omit["030A"] = omit["030B"] = omit["030C"] = 1
+	omit["030F"] = omit["0311"] = omit["0313"] = 1
+	omit["0314"] = omit["0342"] = omit["0653"] = 1
+	omit["0654"] = 1
+}
+$3 == "Mn" && $4 == "230" && $5 == "NSM" && $6 == "" && !omit[$1] {
+	point[++count] = $1
+}
+END {
+	if (count != 297) {
+		printf "expected 297 diacritics, found %u\n", count > "/dev/stderr"
+		exit 1
+	}
+	print "static const uint32_t kitty_diacritics[] = {"
+	for (i = 1; i <= count; i++) {
+		if ((i - 1) % 8 == 0)
+			printf "\t"
+		printf "0x%s", point[i]
+		if (i != count)
+			printf ","
+		if (i == count || i % 8 == 0)
+			printf "\n"
+		else
+			printf " "
+	}
+	print "};"
+}
+' "$1"
--- a/tools/image-edge-test.sh
+++ b/tools/image-edge-test.sh
@@ -0,0 +1,104 @@
+#!/bin/sh
+
+# Compact visual check for image subcell geometry and layering. Run inside a
+# tmux pane on Kitty or a SIXEL terminal; it needs at least 90 columns/24 rows.
+
+if [ -z "$TMUX" ]; then
+	echo "Run this script inside tmux." >&2
+	exit 1
+fi
+
+columns=$(tput cols 2>/dev/null || echo 0)
+lines=$(tput lines 2>/dev/null || echo 0)
+if [ "$columns" -lt 90 ] || [ "$lines" -lt 24 ]; then
+	echo "This test needs at least 90 columns and 24 rows." >&2
+	exit 1
+fi
+
+at()
+{
+	printf '\033[%s;%sH' "$1" "$2"
+}
+
+kitty()
+{
+	printf '\033_G%s\033\\' "$1"
+}
+
+kitty_solid()
+{
+	id=$1
+	rgba=$2
+	payload=$(i=0; while [ "$i" -lt 256 ]; do
+		printf "$rgba"
+		i=$((i + 1))
+	done | base64 | tr -d '\n')
+	kitty "a=t,q=2,f=32,s=16,v=16,i=$id;$payload"
+}
+
+sixel_folder()
+{
+	printf '\033P0;1q"1;1;26;26#0;2;50;50;50#1;2;0;0;0#2;2;49;49;49#3;2;33;33;33#4;2;47;47;47#5;2;44;44;44#6;2;48;48;48#2?O?C!5?S!4?__?_?__$#0?_wW!5KGwo_-#0?~~!8?!10@BB}w$#2!12?a_A?A?A?A??@E-#0?~~!7?KK~~KK!7?~~$#2!9?K!6?K-#0?F^[owowowowowowowowooS^F$#2?G!10?@@!7?G??G-\033\\'
+}
+
+feature_info=$(tmux display-message -p \
+    'term=#{client_termname} features=#{client_termfeatures} cells=#{client_cell_width}x#{client_cell_height}')
+
+printf '\033[2J\033[H\033[?25l'
+at 1 2
+printf 'tmux image edge-case check'
+at 2 2
+printf '%s' "$feature_info"
+
+kitty_solid 201 '\377\000\000\377'
+kitty_solid 202 '\000\377\000\377'
+kitty_solid 203 '\000\000\377\377'
+
+# The 26-pixel folder occupies whole grid cells, but its visible right and
+# bottom edges must remain partial rather than stretching to those boundaries.
+at 4 2
+printf '1. partial SIXEL: folder should be the same size as direct output'
+at 4 72
+sixel_folder
+
+# Chawan emits X/Y for its image padding. The red square must begin slightly
+# below and right of the [img] anchor, never over it.
+at 8 2
+printf '2. Kitty X/Y: RED begins below/right of the [img] anchor'
+at 8 72
+printf '[img]'
+at 9 72
+kitty 'a=p,q=2,C=1,i=201,p=1,x=0,y=0,w=16,h=16,c=3,r=2,X=6,Y=6'
+
+# Positive Kitty z overlays text and other lower z images; negative z is
+# below text. The shared red/blue edge makes any wrong order obvious.
+at 12 2
+printf '3. Kitty z: BLUE covers RED; GREEN stays behind TEXT'
+at 12 72
+printf 'TEXT'
+at 12 72
+kitty 'a=p,q=2,C=1,i=202,p=2,x=0,y=0,w=16,h=16,c=4,r=2,z=-1'
+at 14 72
+kitty 'a=p,q=2,C=1,i=201,p=3,x=0,y=0,w=16,h=16,c=4,r=2,z=1'
+at 14 74
+kitty 'a=p,q=2,C=1,i=203,p=4,x=0,y=0,w=16,h=16,c=4,r=2,z=2'
+
+# SIXEL is temporal: a later image covers text, while later text destroys the
+# affected image cells. Both results should match on Kitty and SIXEL output.
+at 18 2
+printf '4. SIXEL after text: folder covers FOLDER'
+at 18 72
+printf 'FOLDER'
+at 18 72
+sixel_folder
+at 21 2
+printf '5. SIXEL before text: TEXT WINS, no folder remnant'
+at 21 72
+sixel_folder
+at 21 72
+printf 'TEXT WINS'
+
+at 23 2
+printf 'Take one screenshot, then press Enter to return to the shell.'
+printf '\033[?25h'
+IFS= read -r _image_edge_reply
--- a/tools/image-visual-test.sh
+++ b/tools/image-visual-test.sh
@@ -0,0 +1,109 @@
+#!/bin/sh
+
+# One-screen visual check for tmux image input and layering. Run this inside a
+# tmux pane attached to Kitty, WezTerm, Microsoft Terminal, or a basic terminal.
+
+if [ -z "$TMUX" ]; then
+	echo "Run this script inside tmux." >&2
+	exit 1
+fi
+
+columns=$(tput cols 2>/dev/null || echo 0)
+lines=$(tput lines 2>/dev/null || echo 0)
+if [ "$columns" -lt 72 ] || [ "$lines" -lt 23 ]; then
+	echo "This test needs at least 72 columns and 23 rows." >&2
+	exit 1
+fi
+
+at()
+{
+	printf '\033[%s;%sH' "$1" "$2"
+}
+
+kitty()
+{
+	printf '\033_G%s\033\\' "$1"
+}
+
+# Transmit a 16x16 solid RGBA texture. A one-pixel texture is unsuitable here
+# because Kitty filters its transparent texture border into scaled edges.
+kitty_solid()
+{
+	id=$1
+	rgba=$2
+	payload=$(i=0; while [ "$i" -lt 256 ]; do
+		printf "$rgba"
+		i=$((i + 1))
+	done | base64 | tr -d '\n')
+	kitty "a=t,q=2,f=32,s=16,v=16,i=$id;$payload"
+}
+
+# A small 26x26 transparent SIXEL folder, used by the supplied bptato tests.
+sixel_folder()
+{
+	printf '\033P0;1q"1;1;26;26#0;2;50;50;50#1;2;0;0;0#2;2;49;49;49#3;2;33;33;33#4;2;47;47;47#5;2;44;44;44#6;2;48;48;48#2?O?C!5?S!4?__?_?__$#0?_wW!5KGwo_-#0?~~!8?!10@BB}w$#2!12?a_A?A?A?A??@E-#0?~~!7?KK~~KK!7?~~$#2!9?K!6?K-#0?F^[owowowowowowowowooS^F$#2?G!10?@@!7?G??G-\033\\'
+}
+
+feature_info=$(tmux display-message -p \
+    'term=#{client_termname} features=#{client_termfeatures} cells=#{client_cell_width}x#{client_cell_height}')
+
+printf '\033[2J\033[H\033[?25l'
+at 1 2
+printf 'tmux image visual check'
+at 2 2
+printf '%s' "$feature_info"
+
+# Red is placed after its text at a positive Kitty z-index, so it must cover
+# the text. Green is placed below the text at a negative Kitty z-index.
+kitty_solid 101 '\377\000\000\377'
+kitty_solid 102 '\000\377\000\377'
+kitty_solid 103 '\000\000\377\377'
+kitty_solid 104 '\377\000\000\177'
+
+at 4 2
+printf '1. positive Kitty z: RED must hide TEXT UNDER at right'
+at 4 62
+printf 'TEXT UNDER'
+at 4 60
+kitty 'a=p,q=2,C=1,i=101,p=1,x=1,y=1,w=14,h=14,c=18,r=2,z=1'
+
+at 7 2
+printf '2. negative Kitty z: GREEN remains behind TEXT ON TOP'
+at 7 60
+kitty 'a=p,q=2,C=1,i=102,p=2,x=1,y=1,w=14,h=14,c=18,r=2,z=-1'
+at 7 62
+printf 'TEXT ON TOP'
+
+at 10 2
+printf '3. Kitty z overlap: RED left, BLUE on top at right'
+at 11 55
+kitty 'a=p,q=2,C=1,i=101,p=3,x=1,y=1,w=14,h=14,c=18,r=3,z=1'
+at 11 64
+kitty 'a=p,q=2,C=1,i=103,p=4,x=1,y=1,w=14,h=14,c=9,r=3,z=2'
+
+at 15 2
+printf '4. alpha: half-transparent RED, dithered on SIXEL'
+at 15 60
+kitty 'a=p,q=2,C=1,i=104,p=5,x=1,y=1,w=14,h=14,c=18,r=2,z=1'
+
+# SIXEL semantics are temporal: later text destroys a SIXEL image, while a
+# later SIXEL image appears over existing text.
+at 18 2
+printf '5. SIXEL after text: folder covers FOLDER at right'
+at 18 65
+printf 'FOLDER'
+at 18 65
+sixel_folder
+
+at 21 2
+printf '6. SIXEL before text: no folder remains behind TEXT WINS'
+at 21 65
+sixel_folder
+at 21 65
+printf 'TEXT WINS'
+
+at 23 2
+printf 'Take one screenshot, then press Enter to return to the shell.'
+at 23 66
+printf '\033[?25h'
+IFS= read -r _image_visual_reply
--- a/tty-draw.c
+++ b/tty-draw.c
@@ -123,6 +123,10 @@ tty_draw_line(struct tty *tty, struct screen *s, u_int px, u_int py, u_int nx,
 	struct grid		*gd = s->grid;
 	const struct grid_cell	*gcp;
 	struct grid_cell	 gc, ngc, last;
+#ifdef ENABLE_IMAGES
+	struct grid_cell	 image_gc;
+	int			 image_status;
+#endif
 	struct grid_line	*gl;
 	u_int			 i, j, last_i, cx, ex, width;
 	u_int			 cellsize, bg;
@@ -247,20 +251,35 @@ tty_draw_line(struct tty *tty, struct screen *s, u_int px, u_int py, u_int nx,

 			if (px >= ex || i >= ex - px) {
 				/* Outside the area being drawn. */
-				empty = nx - i;
 				gcp = &grid_default_cell;
+#ifdef ENABLE_IMAGES
+				image_status = image_get_fallback_at(tty, s, px + i,
+				    py, gcp, &image_gc, style_ctx);
+				if (image_status == 1) {
+					gcp = &image_gc;
+					empty = 0;
+				} else if (image_status == -1)
+					empty = 1;
+				else
+#endif
+					empty = nx - i;
 			} else {
 				/* Get the current cell. */
 				grid_view_get_cell(gd, px + i, py, &gc);
+				gcp = &gc;
+#ifdef ENABLE_IMAGES
+				if (image_get_fallback_at(tty, s, px + i, py, &gc,
+				    &image_gc, style_ctx) == 1)
+					gcp = &image_gc;
+#endif

 				/* Work out empty cells. */
-				empty = tty_draw_line_get_empty(&gc, &last,
-				    nx - i);
+				empty = tty_draw_line_get_empty(gcp, &last, nx - i);
 				if (empty != 0)
-					gcp = &gc;
+					;
 				else {
 					/* Update for codeset if needed. */
-					gcp = tty_check_codeset(tty, &gc);
+					gcp = tty_check_codeset(tty, gcp);

 					/* And for selection. */
 					if (gcp->flags & GRID_FLAG_SELECTED) {
--- a/tty-features.c
+++ b/tty-features.c
@@ -224,9 +224,11 @@ static const struct tty_feature tty_feature_strikethrough = {
 	0
 };

+#define TTY_FEATURE_SYNC "Sync=\\E[?2026%?%p1%{1}%-%tl%eh%;"
+
 /* Terminal supports synchronized updates. */
 static const char *const tty_feature_sync_capabilities[] = {
-	"Sync=\\E[?2026%?%p1%{1}%-%tl%eh%;",
+	TTY_FEATURE_SYNC,
 	NULL
 };
 static const struct tty_feature tty_feature_sync = {
@@ -357,6 +359,18 @@ static const struct tty_feature tty_feature_sixel = {
 	TERM_SIXEL
 };

+/* Terminal has Kitty graphics protocol Unicode placeholder capability. */
+static const char *const tty_feature_kitty_capabilities[] = {
+	"Kty",
+	TTY_FEATURE_SYNC,
+	NULL
+};
+static const struct tty_feature tty_feature_kitty = {
+	"kitty",
+	tty_feature_kitty_capabilities,
+	TERM_KITTY
+};
+
 /* Terminal supports the OSC 9;4 progress bar. */
 static const char *const tty_feature_progressbar_capabilities[] = {
 	"Spb=\\E]9;4;%p1%d;%p2%d\\E\\\\",
@@ -379,6 +393,7 @@ static const struct tty_feature *const tty_features[] = {
 	&tty_feature_extkeys,
 	&tty_feature_focus,
 	&tty_feature_ignorefkeys,
+	&tty_feature_kitty,
 	&tty_feature_margins,
 	&tty_feature_mouse,
 	&tty_feature_osc7,
@@ -609,6 +624,7 @@ tty_default_features(struct client *c, const char *name, u_int version)
 			      "extkeys,"
 			      "focus,"
 		  	      "hyperlinks,"
+			      "sixel,"
 			      "usstyle"
 		},
 		{ .name = "ghostty",
@@ -622,7 +638,20 @@ tty_default_features(struct client *c, const char *name, u_int version)
 			      "osc7,"
 			      "sync,"
 			      "usstyle,"
-			      "progressbar"
+			      "progressbar,"
+			      "kitty"
+		},
+		{ .name = "kitty",
+		  .features = TTY_FEATURES_BASE_MODERN_XTERM ","
+			      "ccolour,"
+			      "cstyle,"
+			      "extkeys,"
+			      "focus,"
+			      "hyperlinks,"
+			      "osc7,"
+			      "sync,"
+			      "usstyle,"
+			      "kitty"
 		},
 		{ .name = "Rio",
 		  .features = TTY_FEATURES_BASE_MODERN_XTERM ","
--- a/tty-keys.c
+++ b/tty-keys.c
@@ -728,6 +728,7 @@ tty_keys_winsz(struct tty *tty, const char *buf, size_t len, size_t *size)
 		char_y = (ypixel && tty->sy) ? ypixel / tty->sy : 0;
 		tty_set_size(tty, tty->sx, tty->sy, char_x, char_y);
 		tty_invalidate(tty);
+		recalculate_sizes();

 		tty->flags &= ~TTY_WINSIZEQUERY;
 		*size = end + 1;
--- a/tty-term.c
+++ b/tty-term.c
@@ -524,6 +524,7 @@ tty_term_apply_overrides(struct tty_term *term)
 	tty_term_validate(term);
 }

+/* Mark terminals whose Ms capability does not contain a clipboard argument. */
 static void
 tty_term_validate(struct tty_term *term)
 {
--- a/tty.c
+++ b/tty.c
@@ -62,17 +62,15 @@ static void	tty_region(struct tty *, u_int, u_int);
 static void	tty_margin_pane(struct tty *, const struct tty_ctx *);
 static void	tty_margin(struct tty *, u_int, u_int);
 static int	tty_large_region(struct tty *, const struct tty_ctx *);
+static int	tty_scroll_images(struct tty *, const struct tty_ctx *, int *);
 static void	tty_redraw_region(struct tty *, const struct tty_ctx *);
 static void	tty_emulate_repeat(struct tty *, enum tty_code_code,
 		    enum tty_code_code, u_int);
+static void	tty_draw_pane_line(struct tty *, const struct tty_ctx *, u_int,
+		    u_int, u_int, u_int, u_int);
 static void	tty_draw_pane(struct tty *, const struct tty_ctx *, u_int);
 static int	tty_check_overlay(struct tty *, u_int, u_int);

-#ifdef ENABLE_SIXEL
-static void	tty_write_one(void (*)(struct tty *, const struct tty_ctx *),
-		    struct client *, struct tty_ctx *);
-#endif
-
 #define tty_use_margin(tty) \
 	(tty->term->flags & TERM_DECSLRM)
 #define tty_full_width(tty, ctx) \
@@ -163,10 +161,21 @@ tty_resize(struct tty *tty)
 void
 tty_set_size(struct tty *tty, u_int sx, u_int sy, u_int xpixel, u_int ypixel)
 {
+#ifdef ENABLE_IMAGES
+	int	geometry_changed;
+
+	geometry_changed = (tty->xpixel != xpixel || tty->ypixel != ypixel);
+#endif
 	tty->sx = sx;
 	tty->sy = sy;
 	tty->xpixel = xpixel;
 	tty->ypixel = ypixel;
+#ifdef ENABLE_IMAGES
+	if (geometry_changed) {
+		image_tty_geometry_changed(tty);
+		server_redraw_client(tty->client);
+	}
+#endif
 }

 static void
@@ -284,6 +293,10 @@ tty_open(struct tty *tty, char **cause)
 	}
 	tty->flags |= TTY_OPENED;

+#ifdef ENABLE_IMAGES
+	image_tty_update(tty);
+#endif
+
 	tty->flags &= ~(TTY_NOCURSOR|TTY_FREEZE|TTY_BLOCK|TTY_TIMER);

 	event_set(&tty->event_in, c->fd, EV_PERSIST|EV_READ,
@@ -511,6 +524,9 @@ tty_close(struct tty *tty)
 	tty_stop_tty(tty);

 	if (tty->flags & TTY_OPENED) {
+#ifdef ENABLE_IMAGES
+		image_tty_free(tty, 1);
+#endif
 		evbuffer_free(tty->in);
 		event_del(&tty->event_in);
 		evbuffer_free(tty->out);
@@ -527,6 +543,9 @@ void
 tty_free(struct tty *tty)
 {
 	tty_close(tty);
+#ifdef ENABLE_IMAGES
+	image_tty_free(tty, 0);
+#endif

 	free(tty->r.ranges);
 }
@@ -538,6 +557,9 @@ tty_update_features(struct tty *tty)

 	if (tty_apply_features(tty->term))
 		tty_term_apply_overrides(tty->term);
+#ifdef ENABLE_IMAGES
+	image_tty_update(tty);
+#endif

 	if (tty_use_margin(tty))
 		tty_putcode(tty, TTYC_ENMG);
@@ -1071,6 +1093,26 @@ tty_large_region(__unused struct tty *tty, const struct tty_ctx *ctx)
 	return (ctx->orlower - ctx->orupper >= ctx->sy / 2);
 }

+/* Work out whether and how the terminal can scroll image pixels. */
+static int
+tty_scroll_images(struct tty *tty, const struct tty_ctx *ctx, int *full_width)
+{
+	*full_width = 0;
+#ifdef ENABLE_IMAGES
+	if (~ctx->flags & TTY_CTX_IMAGE_SCROLL)
+		return (1);
+	if (image_backend_flags(tty) & IMAGE_BACKEND_SCROLLS)
+		return (1);
+	if (ctx->flags & TTY_CTX_PANE_FULL_WIDTH) {
+		*full_width = 1;
+		return (1);
+	}
+	return (0);
+#else
+	return (1);
+#endif
+}
+
 /*
 * Return if BCE is needed but the terminal doesn't have it - it'll need to be
 * emulated.
@@ -1404,11 +1446,34 @@ tty_clear_pane_area(struct tty *tty, const struct tty_ctx *ctx, u_int py,
 		tty_clear_area(tty, ctx, y, ry, x, rx, bg);
 }

+/* Redraw part of a pane line, including its ordered image layers. */
+static void
+tty_draw_pane_line(struct tty *tty, const struct tty_ctx *ctx, u_int px,
+    u_int py, u_int nx, u_int atx, u_int aty)
+{
+#ifdef ENABLE_IMAGES
+	int	has_images;
+
+	has_images = image_grid_check_area(ctx->s->grid, px,
+	    ctx->s->grid->hsize + py, nx, 1);
+	if (has_images) {
+		image_redraw_start(tty, atx, aty, nx, 1);
+		image_draw_line(tty, ctx->s, px, py, nx, atx, aty, 1,
+		    &ctx->style_ctx);
+	}
+#endif
+	tty_draw_line(tty, ctx->s, px, py, nx, atx, aty, &ctx->style_ctx);
+#ifdef ENABLE_IMAGES
+	if (has_images)
+		image_draw_line(tty, ctx->s, px, py, nx, atx, aty, 0,
+		    &ctx->style_ctx);
+#endif
+}
+
 /* Redraw a line of a screen at py. */
 static void
 tty_draw_pane(struct tty *tty, const struct tty_ctx *ctx, u_int py)
 {
-	struct screen		*s = ctx->s;
 	u_int			 nx = ctx->sx, i, x, rx, ry, j;
 	struct visible_ranges	*r;
 	struct visible_range	*rr;
@@ -1421,8 +1486,8 @@ tty_draw_pane(struct tty *tty, const struct tty_ctx *ctx, u_int py)
 			rr = &r->ranges[j];
 			if (rr->nx == 0)
 				continue;
-			tty_draw_line(tty, s, rr->px - ctx->xoff, py, rr->nx,
-			    rr->px, ctx->yoff + py, &ctx->style_ctx);
+			tty_draw_pane_line(tty, ctx, rr->px - ctx->xoff, py,
+			    rr->nx, rr->px, ctx->yoff + py);
 		}
 		return;
 	}
@@ -1432,8 +1497,8 @@ tty_draw_pane(struct tty *tty, const struct tty_ctx *ctx, u_int py)
 			rr = &r->ranges[j];
 			if (rr->nx == 0)
 				continue;
-			tty_draw_line(tty, s, i + rr->px - x, py, rr->nx,
-			    rr->px, ry, &ctx->style_ctx);
+			tty_draw_pane_line(tty, ctx, i + rr->px - x, py,
+			    rr->nx, rr->px, ry);
 		}
 	}
 }
@@ -1522,60 +1587,6 @@ tty_check_overlay_range(struct tty *tty, u_int px, u_int py, u_int nx)
 	return (c->overlay_check(c, c->overlay_data, px, py, nx));
 }

-#ifdef ENABLE_SIXEL
-/* Update context for client. */
-static int
-tty_set_client_cb(struct tty_ctx *ttyctx, struct client *c)
-{
-	struct window_pane	*wp = ttyctx->arg;
-
-	if (c->session->curw->window != wp->window)
-		return (0);
-	if (wp->layout_cell == NULL)
-		return (0);
-
-	if (tty_window_offset(&c->tty, &ttyctx->wox, &ttyctx->woy, &ttyctx->wsx,
-	    &ttyctx->wsy))
-		ttyctx->flags |= TTY_CTX_WINDOW_BIGGER;
-	else
-		ttyctx->flags &= ~TTY_CTX_WINDOW_BIGGER;
-
-	ttyctx->yoff = ttyctx->ryoff = wp->yoff;
-	if (status_at_line(c) == 0)
-		ttyctx->yoff += status_line_size(c);
-
-	return (1);
-}
-
-void
-tty_draw_images(struct client *c, struct window_pane *wp)
-{
-	struct image	*im;
-	struct tty_ctx	 ttyctx;
-
-	TAILQ_FOREACH(im, &wp->screen->images, entry) {
-		memset(&ttyctx, 0, sizeof ttyctx);
-
-		/* Set the client independent properties. */
-		ttyctx.ocx = im->px;
-		ttyctx.ocy = im->py;
-
-		ttyctx.orlower = wp->screen->rlower;
-		ttyctx.orupper = wp->screen->rupper;
-
-		ttyctx.xoff = ttyctx.rxoff = wp->xoff;
-		ttyctx.sx = wp->sx;
-		ttyctx.sy = wp->sy;
-
-		ttyctx.image = im;
-		ttyctx.arg = wp;
-		ttyctx.set_client_cb = tty_set_client_cb;
-		ttyctx.flags |= TTY_CTX_INVISIBLE_PANES;
-		tty_write_one(tty_cmd_sixelimage, c, &ttyctx);
-	}
-}
-#endif
-
 void
 tty_sync_start(struct tty *tty)
 {
@@ -1649,19 +1660,6 @@ tty_write(void (*cmdfn)(struct tty *, const struct tty_ctx *),
 	}
 }

-#ifdef ENABLE_SIXEL
-/* Only write to the incoming tty instead of every client. */
-static void
-tty_write_one(void (*cmdfn)(struct tty *, const struct tty_ctx *),
-    struct client *c, struct tty_ctx *ctx)
-{
-	if (ctx->set_client_cb == NULL)
-		return;
-	if ((ctx->set_client_cb(ctx, c)) == 1)
-		cmdfn(&c->tty, ctx);
-}
-#endif
-
 void
 tty_cmd_insertcharacter(struct tty *tty, const struct tty_ctx *ctx)
 {
@@ -1709,9 +1707,19 @@ tty_cmd_deletecharacter(struct tty *tty, const struct tty_ctx *ctx)
 void
 tty_cmd_clearcharacter(struct tty *tty, const struct tty_ctx *ctx)
 {
+#ifdef ENABLE_IMAGES
+	u_int	px, py;
+#endif
+
 	tty_default_attributes(tty, ctx->bg, &ctx->style_ctx);

 	tty_clear_pane_line(tty, ctx, ctx->ocy, ctx->ocx, ctx->n, ctx->bg);
+#ifdef ENABLE_IMAGES
+	px = ctx->xoff + ctx->ocx - ctx->wox;
+	py = ctx->yoff + ctx->ocy - ctx->woy;
+	image_draw_after_text(tty, ctx->s, ctx->ocx, ctx->ocy, ctx->n,
+	    px, py, &ctx->style_ctx);
+#endif
 }

 void
@@ -1720,7 +1728,8 @@ tty_cmd_insertline(struct tty *tty, const struct tty_ctx *ctx)
 	struct client	*c = tty->client;

 	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
-	    !tty_full_width(tty, ctx) ||
+	    (!tty_full_width(tty, ctx) &&
+	    (~ctx->flags & TTY_CTX_PANE_FULL_WIDTH)) ||
 	    tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
 	    !tty_term_has(tty->term, TTYC_IL1) ||
@@ -1747,7 +1756,8 @@ tty_cmd_deleteline(struct tty *tty, const struct tty_ctx *ctx)
 	struct client	*c = tty->client;

 	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
-	    !tty_full_width(tty, ctx) ||
+	    (!tty_full_width(tty, ctx) &&
+	    (~ctx->flags & TTY_CTX_PANE_FULL_WIDTH)) ||
 	    tty_fake_bce(tty, &ctx->defaults, ctx->bg) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
 	    !tty_term_has(tty->term, TTYC_DL1) ||
@@ -1798,12 +1808,15 @@ void
 tty_cmd_reverseindex(struct tty *tty, const struct tty_ctx *ctx)
 {
 	struct client	*c = tty->client;
+	int		 full_width;

 	if (ctx->ocy != ctx->orupper)
 		return;

-	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
-	    (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
+	if (!tty_scroll_images(tty, ctx, &full_width) ||
+	    (ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
+	    (!full_width && !tty_full_width(tty, ctx) &&
+	    !tty_use_margin(tty)) ||
 	    tty_fake_bce(tty, &ctx->defaults, 8) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
 	    (!tty_term_has(tty->term, TTYC_RI) &&
@@ -1818,7 +1831,10 @@ tty_cmd_reverseindex(struct tty *tty, const struct tty_ctx *ctx)
 	tty_default_attributes(tty, ctx->bg, &ctx->style_ctx);

 	tty_region_pane(tty, ctx, ctx->orupper, ctx->orlower);
-	tty_margin_pane(tty, ctx);
+	if (full_width)
+		tty_margin_off(tty);
+	else
+		tty_margin_pane(tty, ctx);
 	tty_cursor_pane(tty, ctx, ctx->ocx, ctx->orupper);

 	if (tty_term_has(tty->term, TTYC_RI))
@@ -1831,12 +1847,15 @@ void
 tty_cmd_linefeed(struct tty *tty, const struct tty_ctx *ctx)
 {
 	struct client	*c = tty->client;
+	int		 full_width;

 	if (ctx->ocy != ctx->orlower)
 		return;

-	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
-	    (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
+	if (!tty_scroll_images(tty, ctx, &full_width) ||
+	    (ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
+	    (!full_width && !tty_full_width(tty, ctx) &&
+	    !tty_use_margin(tty)) ||
 	    tty_fake_bce(tty, &ctx->defaults, 8) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
 	    ctx->sx == 1 ||
@@ -1849,7 +1868,10 @@ tty_cmd_linefeed(struct tty *tty, const struct tty_ctx *ctx)
 	tty_default_attributes(tty, ctx->bg, &ctx->style_ctx);

 	tty_region_pane(tty, ctx, ctx->orupper, ctx->orlower);
-	tty_margin_pane(tty, ctx);
+	if (full_width)
+		tty_margin_off(tty);
+	else
+		tty_margin_pane(tty, ctx);

 	/*
 	 * If we want to wrap a pane while using margins, the cursor needs to
@@ -1874,9 +1896,12 @@ tty_cmd_scrollup(struct tty *tty, const struct tty_ctx *ctx)
 {
 	struct client		*c = tty->client;
 	u_int			 i;
+	int			 full_width;

-	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
-	    (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
+	if (!tty_scroll_images(tty, ctx, &full_width) ||
+	    (ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
+	    (!full_width && !tty_full_width(tty, ctx) &&
+	    !tty_use_margin(tty)) ||
 	    tty_fake_bce(tty, &ctx->defaults, 8) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
 	    ctx->sx == 1 ||
@@ -1889,7 +1914,10 @@ tty_cmd_scrollup(struct tty *tty, const struct tty_ctx *ctx)
 	tty_default_attributes(tty, ctx->bg, &ctx->style_ctx);

 	tty_region_pane(tty, ctx, ctx->orupper, ctx->orlower);
-	tty_margin_pane(tty, ctx);
+	if (full_width)
+		tty_margin_off(tty);
+	else
+		tty_margin_pane(tty, ctx);

 	if (ctx->n == 1 || !tty_term_has(tty->term, TTYC_INDN)) {
 		if (!tty_use_margin(tty))
@@ -1912,9 +1940,12 @@ tty_cmd_scrolldown(struct tty *tty, const struct tty_ctx *ctx)
 {
 	u_int		 i;
 	struct client	*c = tty->client;
+	int		 full_width;

-	if ((ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
-	    (!tty_full_width(tty, ctx) && !tty_use_margin(tty)) ||
+	if (!tty_scroll_images(tty, ctx, &full_width) ||
+	    (ctx->flags & TTY_CTX_WINDOW_BIGGER) ||
+	    (!full_width && !tty_full_width(tty, ctx) &&
+	    !tty_use_margin(tty)) ||
 	    tty_fake_bce(tty, &ctx->defaults, 8) ||
 	    !tty_term_has(tty->term, TTYC_CSR) ||
 	    (!tty_term_has(tty->term, TTYC_RI) &&
@@ -1929,7 +1960,10 @@ tty_cmd_scrolldown(struct tty *tty, const struct tty_ctx *ctx)
 	tty_default_attributes(tty, ctx->bg, &ctx->style_ctx);

 	tty_region_pane(tty, ctx, ctx->orupper, ctx->orlower);
-	tty_margin_pane(tty, ctx);
+	if (full_width)
+		tty_margin_off(tty);
+	else
+		tty_margin_pane(tty, ctx);
 	tty_cursor_pane(tty, ctx, ctx->ocx, ctx->orupper);

 	if (tty_term_has(tty->term, TTYC_RIN))
@@ -2052,6 +2086,16 @@ tty_cmd_cell(struct tty *tty, const struct tty_ctx *ctx)
 		if (vis < gcp->data.width) {
 			tty_draw_line(tty, s, s->cx, s->cy, gcp->data.width,
 			    px, py, &ctx->style_ctx);
+#ifdef ENABLE_IMAGES
+			for (i = 0; i < r->used; i++) {
+				if (r->ranges[i].nx == 0)
+					continue;
+				image_draw_after_text(tty, s,
+				    ctx->ocx + r->ranges[i].px - px, ctx->ocy,
+				    r->ranges[i].nx, r->ranges[i].px, py,
+				    &ctx->style_ctx);
+			}
+#endif
 			return;
 		}
 	}
@@ -2068,6 +2112,11 @@ tty_cmd_cell(struct tty *tty, const struct tty_ctx *ctx)

 	tty_cell(tty, ctx->cell, &ctx->style_ctx);

+#ifdef ENABLE_IMAGES
+	image_draw_after_text(tty, s, ctx->ocx, ctx->ocy, gcp->data.width,
+	    px, py, &ctx->style_ctx);
+#endif
+
 	if (ctx->flags & TTY_CTX_CELL_INVALIDATE)
 		tty_invalidate(tty);
 }
@@ -2115,6 +2164,10 @@ tty_cmd_cells(struct tty *tty, const struct tty_ctx *ctx)
 			cx = ri->px - ctx->xoff + ctx->wox;
 			tty_cursor_pane_unless_wrap(tty, ctx, cx, ctx->ocy);
 			tty_putn(tty, cp + ri->px - px, ri->nx, ri->nx);
+#ifdef ENABLE_IMAGES
+			image_draw_after_text(tty, ctx->s, cx, ctx->ocy,
+			    ri->nx, ri->px, py, &ctx->style_ctx);
+#endif
 		}
 	}
 }
@@ -2155,58 +2208,6 @@ tty_cmd_rawstring(struct tty *tty, const struct tty_ctx *ctx)
 	tty_invalidate(tty);
 }

-#ifdef ENABLE_SIXEL
-void
-tty_cmd_sixelimage(struct tty *tty, const struct tty_ctx *ctx)
-{
-	struct image		*im = ctx->image;
-	struct sixel_image	*si = im->data;
-	struct sixel_image	*new;
-	char			*data;
-	size_t			 size;
-	u_int			 cx = ctx->ocx, cy = ctx->ocy, sx, sy;
-	u_int			 i, j, x, y, rx, ry;
-	int			 fallback = 0;
-
-	if ((~tty->term->flags & TERM_SIXEL) &&
-            !tty_term_has(tty->term, TTYC_SXL))
-		fallback = 1;
-	if (tty->xpixel == 0 || tty->ypixel == 0)
-		fallback = 1;
-
-	sixel_size_in_cells(si, &sx, &sy);
-	log_debug("%s: image is %ux%u", __func__, sx, sy);
-	if (!tty_clamp_area(tty, ctx, cx, cy, sx, sy, &i, &j, &x, &y, &rx, &ry))
-		return;
-	log_debug("%s: clamping to %u,%u-%u,%u", __func__, i, j, rx, ry);
-
-	if (fallback == 1) {
-		data = xstrdup(im->fallback);
-		size = strlen(data);
-	} else {
-		new = sixel_scale(si, tty->xpixel, tty->ypixel, i, j, rx, ry, 0);
-		if (new == NULL)
-			return;
-
-		data = sixel_print(new, si, &size);
-	}
-	if (data != NULL) {
-		log_debug("%s: %zu bytes: %s", __func__, size, data);
-		tty_region_off(tty);
-		tty_margin_off(tty);
-		tty_cursor(tty, x, y);
-
-		tty->flags |= TTY_NOBLOCK;
-		tty_add(tty, data, size);
-		tty_invalidate(tty);
-		free(data);
-	}
-
-	if (fallback == 0)
-		sixel_free(new);
-}
-#endif
-
 void
 tty_cmd_syncstart(struct tty *tty, const struct tty_ctx *ctx)
 {
--- a/window-copy.c
+++ b/window-copy.c
@@ -5363,6 +5363,14 @@ window_copy_write_line(struct window_mode_entry *wme,
 	else
 		content_sx = sx;

+#ifdef ENABLE_IMAGES
+	/* Make the backing line's image layers available before drawing text. */
+	image_grid_free_line(s->grid,
+	    &s->grid->linedata[s->grid->hsize + py]);
+	image_grid_copy_area(s->grid, width, s->grid->hsize + py,
+	    data->backing->grid, 0, hsize - data->oy + py, content_sx, 1);
+#endif
+
 	screen_write_cursormove(ctx, 0, py, 0);

 	ft = format_create_defaults(NULL, NULL, NULL, NULL, wp);
@@ -5406,7 +5414,6 @@ window_copy_write_line(struct window_mode_entry *wme,

 	window_copy_write_one(wme, ctx, width, py, hsize - data->oy + py,
 	    content_sx, &mgc, &cgc, &mkgc, &clgc);
-
 	if (py == 0 && s->rupper < s->rlower && !data->hide_position) {
 		value = options_get_string(oo, "copy-mode-position-format");
 		if (*value != '\0') {
Author	SHA1	Message	Date
Michael Grant	6b3d0946b4	docs: preserve established image semantics in redraw plan	2026-08-20 12:25:43 +01:00
Michael Grant	588dc54753	WIP: preserve image redraw experiment and recovery plan	2026-08-19 15:46:09 +01:00
Michael Grant	ec9859b15f	sixel: preserve image aspect across client geometries Scale SIXEL rasters uniformly when clients have different cell dimensions, while retaining the original logical cell canvas as blank padding. Map crops using real cell boundaries so partial final cells are not stretched or compressed.	2026-08-18 22:57:27 +01:00
Michael Grant	3f5f9cab90	build: rename image support option	2026-08-18 12:03:19 +01:00
Michael Grant	33bbd60d98	Merge branch 'master' into 4902-image-support	2026-08-17 21:47:49 +01:00
Michael Grant	48658fd659	Merge branch 'master' into 4902-image-support	2026-08-17 21:39:27 +01:00
Michael Grant	1962365106	Cleanup and simplification.	2026-08-17 08:42:29 +01:00
Michael Grant	870dba6664	Fix indents.	2026-08-17 07:19:56 +01:00
Michael Grant	6ef98552da	Readability and clarity.	2026-08-16 17:09:11 +01:00
Michael Grant	a4abd61663	image: add manual visual checks	2026-08-10 15:46:47 +01:00
Michael Grant	b263d13df0	image: preserve fractional cell extents	2026-08-10 15:08:26 +01:00
Michael Grant	dadc6ef69f	image: select backend after terminal setup	2026-08-10 14:34:16 +01:00
Michael Grant	001b10f2b3	image: retain ordered placements in the grid Replace the per-cell image marker with sparse placement spans attached to grid lines. A placement owns all of its spans and records the input protocol, application image and placement IDs, z-index, and creation order. This retains overlapping image layers without storing a list in every grid cell. Grid operations move, split, clip, and remove only the affected spans. Use the input protocol to determine image/text interaction: later text damages SIXEL spans, while Kitty placements remain and are ordered by their z-index. Rendering then adapts that one logical scene for each client, rather than changing its semantics according to whether the outer terminal uses Kitty or SIXEL.	2026-08-10 12:04:37 +01:00
Michael Grant	a5808bf868	Change some names of things for clarity.	2026-08-09 22:13:15 +01:00
Michael Grant	e97c3d697d	Redraw SIXEL images before or after text depending on which was placed first in the cell.	2026-08-09 08:32:25 +01:00
Michael Grant	c6a59c29ae	The implementation now distinguishes a newly placed image cell from one later overwritten by text. On a SIXEL terminal, damaged cells are omitted from image output; on Kitty they remain ordinary positional placements.	2026-08-08 22:35:10 +01:00
Michael Grant	0ac7289c48	Cleanup.	2026-08-08 22:16:24 +01:00
Michael Grant	7dfd835c3f	Update Kitty image names	2026-08-08 10:58:15 +01:00
Michael Grant	bbcccee9fc	More cleanup of "histogram" name.	2026-08-08 10:51:33 +01:00
Michael Grant	4819dc34df	Shorten image and SIXEL names	2026-08-08 10:51:17 +01:00
Michael Grant	6535274d98	Avoid overflow in image cell size calculation	2026-08-08 10:34:00 +01:00
Michael Grant	9a3b71ac64	Move image cell drawing into image.c	2026-08-08 10:27:31 +01:00
Michael Grant	4c9523c814	Expose image backend flags	2026-08-08 10:22:05 +01:00
Michael Grant	7e6c49b5a5	Do not enable sync for SIXEL	2026-08-08 09:14:07 +01:00
Michael Grant	468259933f	Comment sixel_from_image().	2026-08-07 22:42:22 +01:00
Michael Grant	4380fceb2b	Add comments to image functions	2026-08-07 22:16:16 +01:00
Michael Grant	08c237f0cb	Preserve text behind transparent Kitty images.	2026-08-07 22:06:09 +01:00
Michael Grant	5d0d6c29b4	Revert "Clear text beneath SIXEL image placements." This reverts commit `64cea48f91`.	2026-08-07 19:14:46 +01:00
Michael Grant	64cea48f91	Clear text beneath SIXEL image placements.	2026-08-07 16:39:28 +01:00
Michael Grant	bc998ede98	Ordinary text writes replaced the entire grid cell, dropping GRID_FLAG_IMAGE and releasing the mage reference. Deferred pane redraws explain the intermittent “image never appears” behavior. Fixed: - Preserves image metadata while updating the text underlay in the collected ASCII path: grid.c:779 - Handles the single-cell/non-ASCII path and schedules an image redraw: screen-write.c:2631 - Uses the requested if/else for new_id. - Adds a deterministic regression reproducing point (2): regress/image-support.sh:240 This matches Kitty’s requirement that normal text operations must not affect graphics; graphics require explicit deletion. Kitty graphics protocol	2026-08-07 16:13:07 +01:00
Michael Grant	5c496c765a	Preserve Kitty image crop width after cell rounding.	2026-08-07 16:09:00 +01:00
Michael Grant	3cd6526d46	Fix underlay bookkeeping bug.	2026-08-07 11:34:16 +01:00
Michael Grant	1dacc18ce0	Dither alpha in SIXEL output	2026-08-07 11:21:10 +01:00
Michael Grant	e3f6c1849d	Revert "Clear text beneath graphical images" This reverts commit `fb589fd9f9`.	2026-08-07 09:27:20 +01:00
Michael Grant	a8dfb979e6	Use compact image references in grid cells	2026-08-06 22:36:46 +01:00
Michael Grant	fb589fd9f9	Clear text beneath graphical images	2026-08-06 22:17:19 +01:00
Michael Grant	945152029d	Pass through wrapped Kitty graphics	2026-08-06 19:08:59 +01:00
Michael Grant	8536e26517	Simplify image support terminology	2026-08-06 16:17:25 +01:00
Michael Grant	01d5c9f420	Use one image support switch	2026-08-06 14:27:33 +01:00
Michael Grant	a35871110f	Make image types opaque	2026-08-06 12:24:10 +01:00
Michael Grant	cdff709ab3	Inline basic image fallback renderer	2026-08-06 10:25:29 +01:00
Michael Grant	2788616b6f	Add bptato's test to the regression test script.	2026-08-06 09:11:45 +01:00
Michael Grant	51f1c0de51	The two Chawan symptoms now have matching fixes: - Layout corruption: C=1 is respected. - Lingering remnants: tmux now tracks Kitty’s (image ID, placement ID) identity, replaces moved placements, and honors placement-specific d=i,...,p=... deletion.	2026-08-06 00:06:59 +01:00
Michael Grant	045a25c89a	Support Kitty Unicode placeholder image transmission - Parse Kitty graphics commands wrapped in tmux passthrough sequences. - Accept unpadded base64 payloads emitted by icat. - Handle chunked transfers whose final chunk omits m. - Track virtual image placements. - Convert Unicode placeholders into shared image cells for Kitty and SIXEL clients. - Add regression coverage for wrapped, chunked, unpadded input.	2026-08-05 23:26:11 +01:00
Michael Grant	abfd8cee51	Fix SIXEL median-cut palette generation	2026-08-05 21:44:25 +01:00
Michael Grant	ccc90ea220	Revert "Removed unconditional Floyd–Steinberg dithering from image-sixel.c:1077. Kitty images now use the adaptive 256-colour median-cut palette with direct nearest-colour mapping." This reverts commit `ab591ae430`.	2026-08-05 21:38:28 +01:00
Michael Grant	6cb01394ed	Merge remote-tracking branch 'origin/master' into 4902-image-support # Conflicts: # tmux.h	2026-08-05 14:17:14 +01:00
Michael Grant	6b8d581135	Fix kitty image resize issue when the kitty image resized smaller than the image, the image was overflowing lines and banding.	2026-08-05 13:51:07 +01:00
Michael Grant	ab591ae430	Removed unconditional Floyd–Steinberg dithering from image-sixel.c:1077. Kitty images now use the adaptive 256-colour median-cut palette with direct nearest-colour mapping.	2026-08-05 13:22:15 +01:00
Michael Grant	d06eb0bc2b	C=1 is parsed and stored as an image-placement flag, suppressing cursor movement and scrolling as required by the Kitty protocol.	2026-08-05 11:54:22 +01:00
Michael Grant	2a0e47fef0	Merge branch 'master' into 4902-image-support	2026-08-05 11:10:58 +01:00
Michael Grant	3d07d479db	Keep SIXEL palettes across redraw spans	2026-08-04 08:25:34 +01:00
Michael Grant	ff9b3e5cd7	Rename image damage functions to redraw	2026-08-03 13:15:04 +01:00
Michael Grant	9416ffe9bf	Correct image copyrights	2026-08-03 12:56:26 +01:00
Michael Grant	748fb9ff1c	Remove obsolete Kitty diacritics comment	2026-08-03 12:55:58 +01:00
Michael Grant	cfab0590a4	Support Kitty source rectangle placements	2026-08-03 12:31:11 +01:00
Michael Grant	a4b8d1c822	Improve SIXEL colour quantization Build an adaptive 256-colour palette with median cut instead of using a fixed colour cube. Apply Floyd-Steinberg error diffusion while mapping pixels to reduce banding and preserve image detail.	2026-08-03 12:24:55 +01:00
Michael Grant	7748e525a4	Preserve SIXEL pixel dimensions Retain the padded canonical pixel canvas separately from the image content. Scale only the populated portion of partial edge cells so an image keeps its exact raster size on the originating terminal while retaining its cell footprint.	2026-08-03 12:24:55 +01:00
Michael Grant	01db040717	Correct SIXEL HLS colour conversion Use the DEC hue origin and channel order, and round percentage and HLS conversions to the nearest byte value.	2026-08-03 12:22:23 +01:00
Michael Grant	94f6f3b125	Redraw images after pixel geometry changes A resize may temporarily leave the terminal cell pixel dimensions unknown while tmux queries the terminal. Schedule another client redraw when the pixel geometry response arrives so the graphical backend replaces the temporary text fallback.	2026-08-03 10:49:41 +01:00
Michael Grant	da6812d15f	Use sixel images for WezTerm Enable the sixel feature when WezTerm is detected and clarify that the kitty terminal feature requires Unicode placeholder support rather than only the basic graphics protocol.	2026-08-03 10:39:11 +01:00
Michael Grant	791752ffff	Remove local image ASCII test tool references	2026-08-03 09:24:16 +01:00
Michael Grant	fe938ea657	Refactor to centralize image-specific rendering and lifecycle code in image.c and the image-* backends.	2026-08-03 09:13:45 +01:00
Michael Grant	f68aad1b41	Add tool to generate the kitty diacritics directly from the public UnicodeData.txt file.	2026-08-02 16:15:51 +01:00
Michael Grant	7225365b29	Add missing regression test files.	2026-08-02 12:37:09 +01:00
Michael Grant	d50902b14d	Move image-diacritics.h into image-kitty.c.	2026-08-02 10:41:59 +01:00
Michael Grant	4c04fc805e	Fix copyrights.	2026-08-02 10:38:26 +01:00
Michael Grant	27f12454a1	Add missing .h file.	2026-08-02 10:36:49 +01:00
Michael Grant	fe5f775f76	New image related files.	2026-08-01 08:27:42 +01:00
Michael Grant	4da7f897ea	Fix image flickering.	2026-07-30 22:47:31 +01:00
Michael Grant	9a2060db06	Merge branch '4902-image-support' of github.com:tmux/tmux into 4902-image-support	2026-07-30 22:16:16 +01:00
Michael Grant	f4a57f8b95	Initial commit. Implement generalised image support.	2026-07-30 22:15:53 +01:00