[CTX-1005] feat(vt,platform,runtime,terminal): OSC 22 pointer shapes to cursor icons

[Xuepoo]

Priority: P2 | Area: area:term | Labels: feat,P2,area:term | Milestone: v0.1.0 | RFC: OQ-077 | Task: CTX-1005

Closes #1762.

Implements OSC 22 pointer shapes mapped to platform cursor icons:

• bitty-vt: OSC 22 parsing (set/reset/push/pop, X11 aliases, BEL+ST, chunk-invariant); queries deferred as inert OscUnknown.
• bitty-platform: owned CursorIcon + WindowHandle::set_cursor_icon (winit set_cursor wrapper, no winit type escape).
• bitty-term-state: OscPointerShape stays inert (presentation-only, never terminal truth).
• bitty-runtime: per-pane bounded stacks (16), focused-pane icon query, RIS clear, pane-exit drop.
• bitty-terminal: OsCursorSink seam + per-tick change-gated sync.

Tests: vt unit (5), platform cursor (2)+runtime pointer (4), runtime integration (8 incl. unix pane focus/exit/RIS), terminal sink handoff (1). Gates: fmt-check clean, clippy workspace+dev-tools clean, Windows cross-check clean.

Summary by CodeRabbit

• New Features
  • Terminal applications can now update the OS cursor in response to pointer-shape requests, including setting, stacking, and resetting shapes.
  • Cursor shapes are tracked per pane, and the active pane’s shape is reflected in the window cursor. Repeating the current shape does not trigger an unnecessary update.
  • Common cursor shapes and legacy X11 aliases are supported. Unknown shape names fall back to the default cursor, while queries and invalid requests do not change it.

[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Repository UI (base), Organization UI (inherited)
• Review profile: CHILL
• Plan: Advanced
• Run ID: d71057b8-f695-4bfb-926e-dbeb0e469af8

📥 Commits

Reviewing files that changed from the base of the PR and between 43ddd86 and 9e846c9.

📒 Files selected for processing (2)

• crates/bitty-runtime/src/runtime/panes.rs
• crates/bitty-runtime/tests/osc22_pointer_shapes.rs

🚧 Files skipped from review as they are similar to previous changes (1)

• crates/bitty-runtime/tests/osc22_pointer_shapes.rs

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📝 Walkthrough

Walkthrough

OSC 22 sequences now produce VT pointer-shape actions and update per-view runtime state. The focused view’s shape maps to a platform cursor icon, which the terminal applies to the window while suppressing duplicate updates.

Changes

OSC 22 Cursor Shape Flow

Layer / File(s)	Summary
Platform cursor icon API crates/bitty-platform/src/cursor.rs, crates/bitty-platform/src/app.rs, crates/bitty-platform/src/lib.rs	Adds the public CursorIcon type, canonical name conversion, and WindowHandle::set_cursor_icon forwarding to winit.
OSC 22 parsing and action contract crates/bitty-vt/src/action.rs, crates/bitty-vt/src/lib.rs, crates/bitty-vt/src/parser/dispatch.rs, crates/bitty-vt/src/parser/tests.rs	Adds pointer-shape actions and OSC 22 parsing for set, push, pop, and reset operations. Queries and invalid payloads remain unknown actions. Tests cover aliases, limits, and chunked input.
Per-view pointer state and dispatch crates/bitty-runtime/src/runtime/*, crates/bitty-runtime/tests/osc22_pointer_shapes.rs, crates/bitty-term-state/src/state.rs	Tracks bounded pointer-shape stacks by view, applies PTY actions, clears state on reset or pane-session close, and resolves the focused view’s icon. Tests cover stack behavior, focus, and pane isolation.
Focused icon handoff to the window crates/bitty-terminal/src/terminal_app.rs, crates/bitty-terminal/src/tests.rs	Synchronizes the focused view’s icon on each tick and applies changed icons through a window-backed sink. Tests verify handoff order and duplicate suppression.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant OSC22Parser
  participant Runtime
  participant PointerStacks
  participant TerminalApp
  participant WindowHandle
  OSC22Parser->>Runtime: Emit pointer-shape action
  Runtime->>PointerStacks: Update stack for visible view
  TerminalApp->>PointerStacks: Read focused view shape
  TerminalApp->>WindowHandle: Apply changed cursor icon

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Merge Risk: ⚪ Minimal · up to 9e846

Respawn and pane-session close clear stale cursor shapes, returning the cursor to Default. No concrete issue remains that requires delaying merge.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 9e846

Programs can now change the terminal window’s pointer appearance, but only using predefined icons associated with the focused pane. No privilege expansion was identified. Cleanup evidence is less complete for primary-view retirement than for ordinary pane close and respawn.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — A local or remote program able to supply terminal output can select its view’s predefined pointer appearance. The traced OS effect is confined to the application window’s cursor, selected through current focus; this path does not provide arbitrary cursor assets or process-execution authority.

Trust Boundaries and Controls

• observed — Untrusted PTY bytes cross into window presentation through finite operation parsing, per-ViewId ownership, focused-view selection, and an owned platform enum. The application’s cursor sink is crate-private and does not expose a window handle to the PTY producer.

Resilience and Maintainability Implications

• observed — Replacement and close drop the old session before a bounded forwarder join, then remove its pointer state. Empty pointer state resolves to Default, and unchanged icons are not repeatedly sent to the OS. Inspected tests assert close, respawn, and RIS isolation behavior; they were not executed during this review.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: handling OSC 22 pointer shapes and mapping them to cursor icons across the VT, platform, runtime, and terminal crates.
Linked Issues check	✅ Passed	Issue [#1762] requires OSC 22 parsing, cursor-shape mapping, focused-pane platform updates, reset on pane exit and RIS, and parser and integration tests. The reviewed changes add OSC 22 parsing and `P…
Out of Scope Changes check	✅ Passed	The changes to bitty-vt, bitty-platform, bitty-term-state, bitty-runtime, and bitty-terminal implement OSC 22 parsing, presentation-only state handling, platform cursor dispatch, and focused…
Docstring Coverage	✅ Passed	Docstring coverage is 80.60% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 67 functions across 15 files.

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[coderabbitai]

Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
Review comments at @crates/bitty-runtime/src/runtime/panes.rs:
- Around line 623-627: Update spawn_shell_for_view_impl to remove the respawned
view’s entry from pointer_stacks alongside the existing kitty_images origin
cleanup, so a fresh shell does not inherit the previous session’s cursor shape.

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ℹ️ Review info

⚙️ Run configuration

• Configuration used: Repository UI (base), Organization UI (inherited)
• Review profile: CHILL
• Plan: Advanced
• Run ID: 4ac55c88-10d5-41d2-bf27-ca9eccdb16e4

📥 Commits

Reviewing files that changed from the base of the PR and between d5ca8e5 and 43ddd86.

📒 Files selected for processing (15)

• crates/bitty-platform/src/app.rs
• crates/bitty-platform/src/cursor.rs
• crates/bitty-platform/src/lib.rs
• crates/bitty-runtime/src/runtime.rs
• crates/bitty-runtime/src/runtime/panes.rs
• crates/bitty-runtime/src/runtime/pointer.rs
• crates/bitty-runtime/src/runtime/pty.rs
• crates/bitty-runtime/tests/osc22_pointer_shapes.rs
• crates/bitty-term-state/src/state.rs
• crates/bitty-terminal/src/terminal_app.rs
• crates/bitty-terminal/src/tests.rs
• crates/bitty-vt/src/action.rs
• crates/bitty-vt/src/lib.rs
• crates/bitty-vt/src/parser/dispatch.rs
• crates/bitty-vt/src/parser/tests.rs

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 7 remain after this review.

[Xuepoo]

Independent review: NEEDS-FIX (CTX-1005 reviewer identity)

Reviewed the full diff of ctx-1005/feat-osc22-pointer-shapes against the issue #1762 claims. What verifies:

• vt parsing: reset (empty), set (bare and =-prefixed), push (>list, last-is-top), pop (<, trailing ignored), and query-deferred (?... stays inert OscUnknown with no reply synthesized); BEL and ST terminators; chunk-invariance at sizes 1/2/3/5/7; unknown names fail open to Default (per-entry inside pushes); over-cap pushes fail closed as inert; X11 cursor-font aliases mapped. 5 vt unit tests.
• Per-pane bounded stacks: PointerStacks keyed by ViewId, cap 16 with oldest-eviction, set-replace, pop no-op on empty, per-view isolation — unit plus headless tests.
• Reset on exit / RIS: FullReset clears the emitting pane only (cross-pane RIS test proves the neighbor keeps its shape); close_pane_session drops the stack; term-state stays inert by contract; platform dispatch is change-gated (apply_cursor_icon + cursor_applies counter) through the OsCursorSink seam with an exact-sequence test including no-churn on repeats.

Blocking (2):

1. CI is not green. Linux X11 failed on plugin_workspace::list_is_bounded_at_max_workspaces_with_bounded_names (WallClockExceeded, 50/50ms at tests/plugin_workspace.rs:280). That file is untouched by this PR and the signature matches the known wall-clock-budget flake category (CTX-1001 / issue [P2] plugin_ui mount_loop wall-clock budget flakes under CI load #1744), so it reads as unrelated — but the merge gate requires green, so please re-run to confirm. Windows was still pending and the CodeRabbit check still in progress at review time; both must complete green.
2. CodeRabbit minor on panes.rs:627 is valid. spawn_shell_for_view_impl replaces the session on the same ViewId and already clears kitty_images for exactly this staleness reason, but keeps the old pointer_stacks entry — a respawned shell inherits the dead shell's cursor (e.g. a stuck wait icon). Requested one-line fix per the thread (pointer_stacks.remove next to the kitty_images cleanup), plus a respawn test if cheap.

Integration conflict (commander attention): this PR's cursor::CursorIcon (34 variants) collides with #1771's event::CursorIcon (3 variants) plus a duplicate WindowHandle::set_cursor_icon. Each is mergeable to main alone. Suggested order: land this first (platform superset plus sink seam), then #1771 rebases onto it; the two cursor sync paths (per-tick OSC22 vs hover pointer) need one explicit precedence — proposal: live hover Pointer wins, else focused OSC22 shape, else Default.

Verdict: NEEDS-FIX. Happy to re-review after green CI plus the respawn-clear fix.

[Xuepoo]

Delta independent review: APPROVE (CTX-1005-delta-reviewer)

Re-reviewed PR #1772 at 9e846c97 (fix: clear pointer stack on pane respawn) against the prior NEEDS-FIX (CTX-1005 reviewer + CodeRabbit minor on panes.rs:627).

Fix addresses NEEDS-FIX: spawn_shell_for_view_impl now does self.pointer_stacks.remove(&view) next to the existing kitty_images.clear_origin(Some(view.0)) (panes.rs:410-417), with matching comment citing the same staleness class + close-path removal. Exact one-liner requested. New regression test panes::respawn_clears_stale_shape sets wait, respawns same ViewId, asserts Default.

Negative control (fail-without-fix): verified in scratch worktree at parent 43ddd86 + fix test file only — respawn_clears_stale_shape FAILS without the fix (left: Wait, right: Default, respawned shell must not inherit...), passes with it. Valid regression test.

Affected suites green (fix head 9e846c97):

• cargo test -p bitty-runtime --test osc22_pointer_shapes: 9 passed (incl. new respawn test)
• cargo test -p bitty-vt: 169 passed (incl. osc22_* chunk-invariance, aliases)
• cargo test -p bitty-terminal --bin bitty cursor: 2 passed (osc22_cursor_handoff_call_sequence_reaches_the_os_sink)

CI green: all required checks SUCCESS on 9e846c97 — Quality gates (1)/(2), MSRV 1.85, Linux X11 (xvfb), Linux Wayland, macOS ARM64, Windows, Supply chain, M1 matrix, Compat matrix, CodeQL (rust+actions), CodeRabbit SUCCESS. mergeable: MERGEABLE, mergeStateStatus: BLOCKED only for REVIEW_REQUIRED (this review).

CodeRabbit: latest review d71057b8 — "No actionable comments", Merge Risk Minimal, arch Low with no retained concerns. Prior panes.rs:627 thread marked ✅ Addressed in 9e846c9. No new blockers.

Verdict: APPROVE. Merge order note: land this first (34-variant cursor::CursorIcon superset); #1771 rebases onto it after.