diff --git a/.github/vouch/AGENTS.md b/.github/vouch/AGENTS.md
index eb2b0e70c..248d4b599 100644
--- a/.github/vouch/AGENTS.md
+++ b/.github/vouch/AGENTS.md
@@ -5,9 +5,10 @@ A file for [guiding coding agents](https://agents.md/).
 - All commands must have a `--dry-run` option that is default on.
 - Commands that do not modify external state don't need a `--dry-run` option.
 - The order of definitions in Nu files should be:
-  (1) CLI commands (exported, sorted alphabetically)
-  (2) Helper commands (exported)
-  (3) Helper commands (non exported)
+  (1) General CLI commands (exported, sorted alphabetically)
+  (2) Platform-specific CLI commands like GitHub (exported, `gh-`)
+  (3) Helper commands (exported)
+  (4) Helper commands (non exported)
 - Verify help output using `use <module> *; help <def>`. Everything
   must have human-friendly help output.
 - See `VOUCHED.example` for an example vouch file.
diff --git a/.github/vouch/vouch.nu b/.github/vouch/vouch.nu
index 367770cbd..6dc67e73d 100755
--- a/.github/vouch/vouch.nu
+++ b/.github/vouch/vouch.nu
@@ -35,18 +35,14 @@ export def main [] {
 #   ./vouch.nu add someuser --write
 #
 #   # Add with platform prefix
-#   ./vouch.nu add someuser --platform github --write
+#   ./vouch.nu add github:someuser --write
 #
 export def "main add" [
-  username: string,          # Username to vouch for
-  --platform: string = "",   # Platform prefix (e.g., "github")
+  username: string,          # Username to vouch for (supports platform:user format)
+  --default-platform: string = "", # Assumed platform for entries without explicit platform
   --vouched-file: string,    # Path to vouched contributors file (default: VOUCHED or .github/VOUCHED)
   --write (-w),              # Write the file in-place (default: output to stdout)
 ] {
-  if ($username | str starts-with "-") and ($platform | is-empty) {
-    error make { msg: "platform is required when username starts with -" }
-  }
-
   let file = if ($vouched_file | is-empty) {
     let default = default-vouched-file
     if ($default | is-empty) {
@@ -63,13 +59,12 @@ export def "main add" [
   let contributors = $lines
     | where { |line| not (($line | str starts-with "#") or ($line | str trim | is-empty)) }
 
-  let new_contributors = add-user $username $contributors --platform $platform
+  let new_contributors = add-user $username $contributors --default-platform $default_platform
   let new_content = ($comments | append $new_contributors | str join "\n") + "\n"
 
   if $write {
     $new_content | save -f $file
-    let entry = if ($platform | is-empty) { $username } else { $"($platform):($username)" }
-    print $"Added ($entry) to vouched contributors"
+    print $"Added ($username) to vouched contributors"
   } else {
     print -n $new_content
   }
@@ -102,10 +97,8 @@ export def "main gh-manage-by-issue" [
   --vouched-file: string,  # Path to vouched contributors file (default: VOUCHED or .github/VOUCHED)
   --allow-vouch = true,   # Enable "lgtm" handling to vouch for contributors
   --allow-denounce = true, # Enable "denounce" handling to denounce users
-  --explicit-platform = false, # Add platform prefix (github:) to entries
   --dry-run = true,        # Print what would happen without making changes
 ] {
-  let platform = if $explicit_platform { "github" } else { "" }
   let file = if ($vouched_file | is-empty) {
     let default = default-vouched-file
     if ($default | is-empty) {
@@ -159,7 +152,7 @@ export def "main gh-manage-by-issue" [
   let lines = open-vouched-file $file
 
   if $is_lgtm {
-    let status = check-user $issue_author $lines --platform github --default-platform github
+    let status = check-user $issue_author $lines --default-platform github
     if $status == "vouched" {
       print $"($issue_author) is already vouched"
 
@@ -175,18 +168,17 @@ export def "main gh-manage-by-issue" [
       return
     }
 
-    let entry = if ($platform | is-empty) { $issue_author } else { $"($platform):($issue_author)" }
     if $dry_run {
-      print $"(dry-run) Would add ($entry) to ($file)"
+      print $"(dry-run) Would add ($issue_author) to ($file)"
       print "vouched"
       return
     }
 
-    let new_lines = add-user $issue_author $lines --platform $platform
+    let new_lines = add-user $issue_author $lines --default-platform github
     let new_content = ($new_lines | str join "\n") + "\n"
     $new_content | save -f $file
 
-    print $"Added ($entry) to vouched contributors"
+    print $"Added ($issue_author) to vouched contributors"
     print "vouched"
     return
   }
@@ -200,22 +192,21 @@ export def "main gh-manage-by-issue" [
     }
     let reason = $match.capture1? | default ""
 
-    let status = check-user $target_user $lines --platform github --default-platform github
+    let status = check-user $target_user $lines --default-platform github
     if $status == "denounced" {
       print $"($target_user) is already denounced"
       print "unchanged"
       return
     }
 
-    let handle = if ($platform | is-empty) { $target_user } else { $"($platform):($target_user)" }
     if $dry_run {
-      let entry = if ($reason | is-empty) { $"-($handle)" } else { $"-($handle) ($reason)" }
+      let entry = if ($reason | is-empty) { $"-($target_user)" } else { $"-($target_user) ($reason)" }
       print $"(dry-run) Would add ($entry) to ($file)"
       print "denounced"
       return
     }
 
-    let new_lines = denounce-user $target_user $reason $lines --platform $platform
+    let new_lines = denounce-user $target_user $reason $lines --default-platform github
     let new_content = ($new_lines | str join "\n") + "\n"
     $new_content | save -f $file
 
@@ -242,19 +233,15 @@ export def "main gh-manage-by-issue" [
 #   ./vouch.nu denounce badactor --write
 #
 #   # Denounce with platform prefix
-#   ./vouch.nu denounce badactor --platform github --write
+#   ./vouch.nu denounce github:badactor --write
 #
 export def "main denounce" [
-  username: string,          # Username to denounce
+  username: string,          # Username to denounce (supports platform:user format)
+  --default-platform: string = "", # Assumed platform for entries without explicit platform
   --reason: string,          # Optional reason for denouncement
-  --platform: string = "",   # Platform prefix (e.g., "github")
   --vouched-file: string,    # Path to vouched contributors file (default: VOUCHED or .github/VOUCHED)
   --write (-w),              # Write the file in-place (default: output to stdout)
 ] {
-  if ($username | str starts-with "-") and ($platform | is-empty) {
-    error make { msg: "platform is required when username starts with -" }
-  }
-
   let file = if ($vouched_file | is-empty) {
     let default = default-vouched-file
     if ($default | is-empty) {
@@ -266,13 +253,12 @@ export def "main denounce" [
   }
 
   let lines = open-vouched-file $file
-  let new_lines = denounce-user $username $reason $lines --platform $platform
+  let new_lines = denounce-user $username $reason $lines --default-platform $default_platform
   let new_content = ($new_lines | str join "\n") + "\n"
 
   if $write {
     $new_content | save -f $file
-    let handle = if ($platform | is-empty) { $username } else { $"($platform):($username)" }
-    print $"Denounced ($handle)"
+    print $"Denounced ($username)"
   } else {
     print -n $new_content
   }
@@ -290,12 +276,12 @@ export def "main denounce" [
 # Examples:
 #
 #   ./vouch.nu check someuser
+#   ./vouch.nu check github:someuser
 #   ./vouch.nu check someuser --vouched-file path/to/VOUCHED
-#   ./vouch.nu check someuser --platform github --default-platform github
+#   ./vouch.nu check someuser --default-platform github
 #
 export def "main check" [
-  username: string,          # Username to check
-  --platform: string = "",   # Platform to match (e.g., "github"). Empty matches any.
+  username: string,          # Username to check (supports platform:user format)
   --default-platform: string = "", # Assumed platform for entries without explicit platform
   --vouched-file: string,    # Path to vouched contributors file (default: VOUCHED or .github/VOUCHED)
 ] {
@@ -306,7 +292,7 @@ export def "main check" [
     exit 1
   }
 
-  let status = check-user $username $lines --platform $platform --default-platform $default_platform
+  let status = check-user $username $lines --default-platform $default_platform
   print $status
   match $status {
     "vouched" => { exit 0 }
@@ -343,10 +329,8 @@ export def "main gh-check-pr" [
   --vouched-file: string = ".github/VOUCHED", # Path to vouched contributors file
   --require-vouch = true,    # Require users to be vouched; if false, only denounced users are blocked
   --auto-close = false,      # Close unvouched PRs with a comment
-  --explicit-platform = false, # Require platform prefix (github:) when matching
   --dry-run = true,          # Print what would happen without making changes
 ] {
-  let platform = if $explicit_platform { "github" } else { "" }
   let owner = ($repo | split row "/" | first)
   let repo_name = ($repo | split row "/" | last)
 
@@ -379,7 +363,7 @@ export def "main gh-check-pr" [
   let file_data = github api "get" $"/repos/($owner)/($repo_name)/contents/($vouched_file)?ref=($default_branch)"
   let content = $file_data.content | decode base64 | decode utf-8
   let lines = $content | lines
-  let status = check-user $pr_author $lines --platform github --default-platform github
+  let status = check-user $pr_author $lines --default-platform github
 
   if $status == "vouched" {
     print $"($pr_author) is in the vouched contributors list"
@@ -467,17 +451,18 @@ This PR will be closed automatically. See https://github.com/($owner)/($repo_nam
 # Supports platform:username format (e.g., github:mitchellh).
 # Returns "vouched", "denounced", or "unknown".
 export def check-user [
-  username: string,            # Username to check
+  username: string,            # Username to check (supports platform:user format)
   lines: list<string>,         # Lines from the vouched file
-  --platform: string = "",     # Platform to match (e.g., "github"). Empty matches any.
   --default-platform: string = "", # Assumed platform for entries without explicit platform
 ] {
   let contributors = $lines
     | where { |line| not (($line | str starts-with "#") or ($line | str trim | is-empty)) }
 
-  let username_lower = ($username | str downcase)
-  let platform_lower = ($platform | str downcase)
+  let parsed_input = parse-handle $username
+  let input_user = $parsed_input.username
+  let input_platform = $parsed_input.platform
   let default_platform_lower = ($default_platform | str downcase)
+
   for line in $contributors {
     let handle = ($line | str trim | split row " " | first)
     
@@ -489,10 +474,13 @@ export def check-user [
     let entry_platform = if ($parsed.platform | is-empty) { $default_platform_lower } else { $parsed.platform }
     let entry_user = $parsed.username
     
-    # Match if usernames match and (no platform filter OR platforms match)
-    let platform_matches = ($platform_lower | is-empty) or ($entry_platform | is-empty) or ($entry_platform == $platform_lower)
+    # Determine platform to match against
+    let check_platform = if ($input_platform | is-empty) { $default_platform_lower } else { $input_platform }
     
-    if ($entry_user == $username_lower) and $platform_matches {
+    # Match if usernames match and platforms match (or either is empty)
+    let platform_matches = ($check_platform | is-empty) or ($entry_platform | is-empty) or ($entry_platform == $check_platform)
+    
+    if ($entry_user == $input_user) and $platform_matches {
       if $is_denounced {
         return "denounced"
       } else {
@@ -505,17 +493,18 @@ export def check-user [
 }
 
 # Add a user to the contributor lines, removing any existing entry first.
+# Comments and blank lines are ignored and preserved.
 #
 # Supports platform:username format (e.g., github:mitchellh).
+#
 # Returns the updated lines with the user added and sorted.
 export def add-user [
-  username: string,            # Username to add
+  username: string,            # Username to add (supports platform:user format)
   lines: list<string>,         # Lines from the vouched file
-  --platform: string = "",     # Platform prefix (e.g., "github")
+  --default-platform: string = "", # Assumed platform for entries without explicit platform
 ] {
-  let filtered = remove-user $username $lines --platform $platform
-  let entry = if ($platform | is-empty) { $username } else { $"($platform):($username)" }
-  $filtered | append $entry | sort -i
+  let filtered = remove-user $username $lines --default-platform $default_platform
+  $filtered | append $username | sort -i
 }
 
 # Denounce a user in the contributor lines, removing any existing entry first.
@@ -523,14 +512,13 @@ export def add-user [
 # Supports platform:username format (e.g., github:mitchellh).
 # Returns the updated lines with the user added as denounced and sorted.
 export def denounce-user [
-  username: string,            # Username to denounce
+  username: string,            # Username to denounce (supports platform:user format)
   reason: string,              # Reason for denouncement (can be empty)
   lines: list<string>,         # Lines from the vouched file
-  --platform: string = "",     # Platform prefix (e.g., "github")
+  --default-platform: string = "", # Assumed platform for entries without explicit platform
 ] {
-  let filtered = remove-user $username $lines --platform $platform
-  let handle = if ($platform | is-empty) { $username } else { $"($platform):($username)" }
-  let entry = if ($reason | is-empty) { $"-($handle)" } else { $"-($handle) ($reason)" }
+  let filtered = remove-user $username $lines --default-platform $default_platform
+  let entry = if ($reason | is-empty) { $"-($username)" } else { $"-($username) ($reason)" }
   $filtered | append $entry | sort -i
 }
 
@@ -540,12 +528,15 @@ export def denounce-user [
 # Supports platform:username format (e.g., github:mitchellh).
 # Returns the filtered lines after removal.
 export def remove-user [
-  username: string,            # Username to remove
+  username: string,            # Username to remove (supports platform:user format)
   lines: list<string>,         # Lines from the vouched file
-  --platform: string = "",     # Platform to match (e.g., "github"). Empty matches any.
+  --default-platform: string = "", # Assumed platform for entries without explicit platform
 ] {
-  let username_lower = ($username | str downcase)
-  let platform_lower = ($platform | str downcase)
+  let parsed_input = parse-handle $username
+  let input_user = $parsed_input.username
+  let input_platform = $parsed_input.platform
+  let default_platform_lower = ($default_platform | str downcase)
+
   $lines | where { |line|
     # Pass through comments and blank lines
     if ($line | str starts-with "#") or ($line | str trim | is-empty) {
@@ -560,12 +551,15 @@ export def remove-user [
     }
 
     let parsed = parse-handle $entry
-    let entry_platform = $parsed.platform
+    let entry_platform = if ($parsed.platform | is-empty) { $default_platform_lower } else { $parsed.platform }
     let entry_user = $parsed.username
     
-    # Keep if username doesn't match OR (platform filter set AND platforms don't match AND entry has platform)
-    let platform_matches = ($platform_lower | is-empty) or ($entry_platform | is-empty) or ($entry_platform == $platform_lower)
-    not (($entry_user == $username_lower) and $platform_matches)
+    # Determine platform to match against
+    let check_platform = if ($input_platform | is-empty) { $default_platform_lower } else { $input_platform }
+    
+    # Keep if username doesn't match OR platforms don't match (when both have platforms)
+    let platform_matches = ($check_platform | is-empty) or ($entry_platform | is-empty) or ($entry_platform == $check_platform)
+    not (($entry_user == $input_user) and $platform_matches)
   }
 }