feat: slash command scrolling & tab completion (SEA-170)

[fluxdiv]

Pull request

Summary

Adds keyboard-navigable slash command autocomplete to the TUI composer with inline ghost text and Tab/Enter to accept completions.

Related issues

Refs SEA-170

Changes

• Slash command suggestion popup now highlights the currently selected row, navigable with Up/Down arrow keys
• Inline ghost text renders after the cursor in a dim style, previewing the completion suffix with [hit \tab` to accept]`
• Tab or plain Enter accepts the selected completion; Enter in paste mode inserts a newline instead
• Exact command match on Enter dispatches the command rather than triggering completion
• Selection index resets when the typed prefix changes and is clamped to the suggestion list size
• Up arrow after typing command arguments moves the composer cursor to the start of the line
• Slash command popup is suppressed when the path mention popup is open
• Introduced SlashCommandCompletion struct carrying the replacement range, replacement text, and ghost text
• Added slash_command_completion, slash_command_selection_key, and active_slash_command helpers in slash_commands.rs
• Added layout_with_ghost to Composer to inject inline ghost text spans at the cursor position without a second layout walk

Test plan

• slash_command_down_and_tab_accept_selected_completion: Down then Tab replaces prefix with full command
• slash_command_enter_accepts_selected_completion: Down then Enter completes without dispatching
• slash_command_enter_in_paste_mode_inserts_newline: Enter in paste mode does not complete
• slash_command_up_after_command_args_moves_composer_cursor: Up with args present moves cursor to start
• slash_command_enter_on_exact_match_still_dispatches: Exact match Enter dispatches the slash command action
• slash_completion_renders_inline_ghost_text: Renderer test confirms ghost text appears after typed prefix
• layout_with_ghost_inserts_text_after_cursor: Composer layout unit test confirms ghost span position and cursor column
• completion_returns_replacement_and_ghost_text, completion_is_none_after_command_token, completion_is_none_inside_command_token, completion_is_none_for_exact_match: Unit tests for slash_command_completion edge cases

[linear-code]

SEA-170

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds slash-command completion state, completion lookup helpers, ghost-text composer layout, renderer selection highlighting, and app key handling for navigating or accepting completions. New tests cover completion resolution, ghost rendering, and popup behavior.

Changes

Slash-command completion UI

Layer / File(s)	Summary
Completion contract and lookup crates/seal-tui/src/slash_commands.rs	Adds completion data, cursor-aware activation, completion resolution, and related tests.
App state and popup keys crates/seal-tui/src/app.rs	Adds completion selection state to ChatState, resyncs it after paste and key handling, and handles popup navigation and completion insertion.
Composer ghost text layout crates/seal-tui/src/composer.rs	Adds layout_with_ghost and inline ghost-text insertion paths for wrapped and unwrapped composer layout.
Renderer integration crates/seal-tui/src/renderer.rs	Passes completion ghost text into composer layout, suppresses it when path mentions are shown, highlights the selected suggestion row, and adds a rendering test.

Sequence Diagram(s)

Keyboard handling

sequenceDiagram
  participant User
  participant handle_key
  participant sync_slash_command_selection
  participant handle_slash_command_popup_keys
  participant slash_command_completion
  participant Composer

  User->>handle_key: paste or press popup key
  handle_key->>sync_slash_command_selection: resync selection key
  handle_key->>handle_slash_command_popup_keys: route Up / Down / Tab / Enter
  handle_slash_command_popup_keys->>slash_command_completion: resolve selected completion
  handle_slash_command_popup_keys->>Composer: insert completion or newline

Loading

Render-time ghost text

sequenceDiagram
  participant Renderer
  participant slash_command_completion
  participant Composer
  participant render_slash_command_suggestions

  Renderer->>slash_command_completion: compute ghost_text for current slash prefix
  Renderer->>Composer: layout_with_ghost(ghost_text)
  Renderer->>render_slash_command_suggestions: render selected row

Loading

Estimated review effort

🎯 4 (Complex) | ⏱️ ~60 minutes

Poem

I hopped by /re with a twitchy nose,
A ghost-text carrot in the cursor glows 🥕
Tab went thump, and Enter went bright,
My bunny paws approve this slashy light.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description is directly related to the changeset and accurately describes the autocomplete, ghost text, and key handling updates.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly matches the main change: slash command autocomplete with keyboard navigation and Tab completion.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 06-24-sea-170

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_{Comment @coderabbitai help to get the list of available commands.}

[fluxdiv]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• feat: slash command scrolling & tab completion (SEA-170) #697 👈 (View in Graphite)
• feat: @ operator for file/directory search suggestions (SEA-83) #683
• main

---

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[greptile-apps]

Greptile Summary

This PR adds keyboard-navigable slash command autocomplete to the TUI composer: Up/Down navigate a highlighted suggestion popup, inline ghost text previews the completion suffix, and Tab or Enter accepts the selected item. An exact-match Enter falls through to dispatch the command rather than completing it, and the slash popup is suppressed when the path-mention popup is open.

• slash_commands.rs: New SlashCommandCompletion struct and slash_command_completion / active_slash_command helpers drive selection and ghost-text generation; coverage is solid.
• composer.rs: layout_with_ghost injects dim ghost-text spans at the cursor position without a second layout walk; chunk boundary logic and byte-to-char indexing are correct.
• app.rs: Selection state and sync are wired into every key-handling path; insert_selected_slash_command_or_newline introduces a double-tick_paste_fsm issue on the exact-match Enter path (see inline comment).

Confidence Score: 4/5

Safe to merge with awareness of the exact-match Enter / paste-FSM interaction; fix before shipping to users who type rapidly or use terminal macros.

The new ghost-text layout and suggestion-list logic are well-tested and correct. The one issue is in insert_selected_slash_command_or_newline: it ticks the paste FSM and then, for an exact command match, returns None so the key re-enters handle_composer_keys, which ticks the FSM a second time. The sub-millisecond gap between the two ticks always qualifies as a rapid keystroke, so one extra paste_burst_count increment is added on every exact-match Enter — under the right pre-existing burst state this silently activates paste mode and inserts a newline instead of dispatching the command. No test covers this path with the FSM enabled.

crates/seal-tui/src/app.rs — specifically insert_selected_slash_command_or_newline and its interaction with the paste-detection FSM on the exact-match Enter path.

Important Files Changed

Filename	Overview
crates/seal-tui/src/app.rs	Adds slash command popup key handling, selection state, and sync; exact-match Enter path double-ticks the paste-detection FSM
crates/seal-tui/src/slash_commands.rs	Adds SlashCommandCompletion struct, slash_command_completion, active_slash_command helpers, and selection key; logic and edge-case tests are thorough
crates/seal-tui/src/composer.rs	Adds layout_with_ghost and push_text_with_inline_ghost for cursor-position ghost text injection; chunk boundary handling and byte/char indexing are correct
crates/seal-tui/src/renderer.rs	Wires slash_command_selected into the suggestion popup renderer and routes ghost text into layout_with_ghost; selection highlight is bold-only on command name

_{Reviews (3): Last reviewed commit: "fix: fix `/reload` then down arrow not s..." | Re-trigger Greptile}

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@crates/seal-tui/src/app.rs`:
- Around line 523-529: The navigation handler in app.rs is returning early from
slash_command_completion before processing the key event, which prevents Down
from moving off an exact-match suggestion like /reload. Update the logic around
App::sync_slash_command_selection and slash_command_completion so the result is
not required for navigation handling; only use the completion outcome when
needed for rendering or selection state, and allow the match on key.code to
continue even when slash_command_completion returns None.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: d09df8ee-3ffa-4362-9625-f9768dac335a

📥 Commits

Reviewing files that changed from the base of the PR and between 413c93a and d50983f.

📒 Files selected for processing (4)

• crates/seal-tui/src/app.rs
• crates/seal-tui/src/composer.rs
• crates/seal-tui/src/renderer.rs
• crates/seal-tui/src/slash_commands.rs

[sealedsecurity-ci]

Docs preview: https://06-24-sea-170.seal-docs.pages.dev

[cubic-dev-ai]

1 issue found across 2 files (changes from recent commits).

<sub>Tip: Review your code locally with the cubic CLI to iterate faster.

Fix all with cubic | Re-trigger cubic</sub>