OSC 22 cursor support

[natemoo-re]

Supercedes #101.

Adds support for the OSC 22 cursor shapes, which supports a subset of the CSS cursor keywords.

The public API is an element that accepts the pointer shape: open(id, { cursor: "pointer" }). The renderer writes the escape sequence directly into result.output. This works in line mode and alt screens.

Review comments from #101 have been addressed and regression tests added.

OSC 22 bytes are only emitted for terminals that report support (using the probe infrastructure added in #132) or have been documented to support the escape sequence without supporting the query form (ghostty).

Demos updated in #144.

[bombshell-cooper]

Changeset suggestion

The current changeset no longer matches this PR. This review contains a corrected replacement.

Why: Changeset package scope does not match the affected packages confidently. Changeset contains implementation or roadmap noise.

View the proposed changeset

---
'@bomb.sh/tty': minor
---

Adds a `cursor` property to `open()` so the mouse pointer changes shape (via OSC 22) while it hovers over an element.

When `term.capabilities.pointerShape` is `true`, `render()` appends the resolved shape to `output` after the frame's cell bytes. The shape resets to `default` when the pointer leaves, when a frame renders without `pointer`, or when `update()` withdraws the capability. `detectTerminal()` seeds `pointerShape: true` for terminals that set shapes without answering the query (ghostty, kitty, foot, xterm ≥ 367). For anything else, assert support with `term.update([{ type: "capability", key: "pointer-shape", value: true }])`.

```ts
term.render([open("link", { cursor: "pointer" }), text("Docs"), close()], { pointer });
```

#### Migration

`pointerShape` moves from `RuntimeCapabilities` to the base `Capabilities` interface so it is present from the first `term.capabilities` read (seeded by `detectTerminal()`, then raised by the probe reply).

```diff
-import type { RuntimeCapabilities } from "@bomb.sh/tty";
+import type { Capabilities } from "@bomb.sh/tty";

-const supported = term.capabilities.pointerShape; // was RuntimeCapabilities-only
+const supported = term.capabilities.pointerShape;  // now available on Capabilities
```

Code that only reads `term.capabilities.pointerShape` will continue to compile; code that constructed a `RuntimeCapabilities` object literal must remove the `pointerShape` field from that object.

Review this changeset manually

If this draft is correct, react with 🚀 and Cooper will commit it to this branch.

[bombshell-cooper]

Changeset needs revision.

Changeset package scope does not match the affected packages confidently. Changeset contains implementation or roadmap noise.

View the proposed replacement

---
'@bomb.sh/tty': minor
---

Adds a `cursor` property to `open()` so the mouse pointer changes shape (via OSC 22) while it hovers over an element.

When `term.capabilities.pointerShape` is `true`, `render()` appends the resolved shape to `output` after the frame's cell bytes. The shape resets to `default` when the pointer leaves, when a frame renders without `pointer`, or when `update()` withdraws the capability. `detectTerminal()` seeds `pointerShape: true` for terminals that set shapes without answering the query (ghostty, kitty, foot, xterm ≥ 367). For anything else, assert support with `term.update([{ type: "capability", key: "pointer-shape", value: true }])`.

```ts
term.render([open("link", { cursor: "pointer" }), text("Docs"), close()], { pointer });
```

#### Migration

`pointerShape` moves from `RuntimeCapabilities` to the base `Capabilities` interface so it is present from the first `term.capabilities` read (seeded by `detectTerminal()`, then raised by the probe reply).

```diff
-import type { RuntimeCapabilities } from "@bomb.sh/tty";
+import type { Capabilities } from "@bomb.sh/tty";

-const supported = term.capabilities.pointerShape; // was RuntimeCapabilities-only
+const supported = term.capabilities.pointerShape;  // now available on Capabilities
```

Code that only reads `term.capabilities.pointerShape` will continue to compile; code that constructed a `RuntimeCapabilities` object literal must remove the `pointerShape` field from that object.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@bomb.sh/tty@137

commit: 6939c47

[github-actions]

Size Increased — +5.2 KB

127.9 KB unpacked

[codspeed]

Merging this PR will degrade performance by 22.15%

❌ 1 regressed benchmark
✅ 9 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	createTerm	280.1 ms	359.8 ms	-22.15%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing feat/pointer-shape (6939c47) with main (2c6215c)}