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feat(term): synchronized output (DEC mode 2026) via the sync-output capability - #139
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… capability Full-screen frames wrap in BSU/ESU when RuntimeCapabilities.syncOutput is true; the flag rides reduce() per frame so a capability flip takes effect on the next rendered frame with no invalidation signal. Zero-diff frames emit zero bytes even when wrapped, and line mode is never wrapped. Renderer-spec 7.9 discharges the deferral recorded in 7.8.
Changeset suggestionThe 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 bump does not match the consumer-visible impact. View the proposed changeset---
'@bomb.sh/tty': minor
---
Adds synchronized output (DEC mode 2026) driven by the `sync-output` capability.
When `RuntimeCapabilities.syncOutput` is true, full-screen frames are wrapped in Begin/End Synchronized Update (`CSI ? 2026 h` / `CSI ? 2026 l`) so the terminal presents each frame as one atomic repaint without tearing. The capability is resolved from three channels: a DECRPM 2026 probe reply, an XTGETTCAP `Sync` reply, and detection-time evidence from the `Sync` extended capability in the terminfo entry or the `TMUX` environment variable. Probe replies outrank detection-time evidence in both directions. No-op frames emit nothing regardless of wrapping state; line mode output is never wrapped.
#### Migration
`Capabilities` gains a required `syncOutput` field. Object literals passed to `createTerm` as `terminfo.capabilities` must include it:
```diff
terminfo: {
capabilities: {
colors: 256,
trueColor: false,
bce: true,
autoMargin: true,
xenl: true,
altScreen: true,
styledUnderline: false,
+ syncOutput: false,
},
}
```Review this changeset manually If this draft is correct, react with 🚀 and Cooper will commit it to this branch. |
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Changeset needs revision.
Changeset package scope does not match the affected packages confidently. Changeset bump does not match the consumer-visible impact.
View the proposed replacement
---
'@bomb.sh/tty': minor
---
Adds synchronized output (DEC mode 2026) driven by the `sync-output` capability.
When `RuntimeCapabilities.syncOutput` is true, full-screen frames are wrapped in Begin/End Synchronized Update (`CSI ? 2026 h` / `CSI ? 2026 l`) so the terminal presents each frame as one atomic repaint without tearing. The capability is resolved from three channels: a DECRPM 2026 probe reply, an XTGETTCAP `Sync` reply, and detection-time evidence from the `Sync` extended capability in the terminfo entry or the `TMUX` environment variable. Probe replies outrank detection-time evidence in both directions. No-op frames emit nothing regardless of wrapping state; line mode output is never wrapped.
#### Migration
`Capabilities` gains a required `syncOutput` field. Object literals passed to `createTerm` as `terminfo.capabilities` must include it:
```diff
terminfo: {
capabilities: {
colors: 256,
trueColor: false,
bce: true,
autoMargin: true,
xenl: true,
altScreen: true,
styledUnderline: false,
+ syncOutput: false,
},
}
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Took the Capabilities.syncOutput migration note in df2169b. It's a public type with a newly required field, so the "no new API" line was wrong. I left out the createTermNative item because that function isn't exported from mod.ts, so it's not a consumer-facing change. Package scope is unchanged (@bomb.sh/tty).
Generated by Claude Code
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Size Increased — +1.6 KB 124.2 KB unpacked |
commit: |
Per the approved spec amendment (terminfo-spec §6.1/§6.3/§7.1/§7.2/§8/§9.1, renderer-spec §7.9): syncOutput is raised only on positive evidence from three channels. - Probe row 8: XTGETTCAP Sync (DCS + q 53796e63) as its own request — some terminals honor only one capability per XTGETTCAP request, so it must not merge into the RGB;Tc query. A value-carrying reply confirms; a reply naming Sync without a value denies. Sync replies never touch the colordepth tally. - Static Capabilities gains syncOutput, seeded from the Sync extended capability in the parsed terminfo entry and from TMUX environment evidence (tmux consumes mode 2026 from inner applications). - TINV-3 precedence: probe replies outrank detect-time seeding in both directions; runtimeFromStatic now flows the seeded field through. The reply's sequence value is discarded in v1: emission remains the DEC mode 2026 form, unchanged from §7.9's normative rules.
| mode, | ||
| row, | ||
| dt, | ||
| currentCaps.syncOutput ? 1 : 0, |
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I thought we were going to move capabilities into the native state rather than copy them over on every call.
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That was indeed the direction we discussed! Oversight on my part, I'll take another pass at this.
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Done in 3142ef2: capabilities now live in native renderer state. set_capabilities(ct, flags) stores a CAP_* bitfield on the Clayterm instance, and reduce() reads it from there instead of taking it as an argument. The host pushes flags once at creation and again from term.update() only when a folded event changes them. The native wrapper re-pushes after re-init, because init() zeroes instance state. 34ab9ca then prefixed the renderer bits to avoid colliding with CAP_SYNC_OUTPUT in input.h.
Generated by Claude Code
Capabilities were copied into reduce() on every render. The renderer now owns them: set_capabilities(ct, flags) stores a CAP_* bitfield on the Clayterm instance, and reduce() reads it from there. The host pushes flags at creation and again from term.update() only when a folded event changes them. init() zeroes instance state, so the native wrapper re-pushes after every re-init; a resize keeps the wrap.
input.h already defines CAP_SYNC_OUTPUT as a CapabilityEvent key (5). Any translation unit including both headers silently redefined it.
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…put field Capabilities is a public export and syncOutput is required, so object literals passed as terminfo.capabilities stop type-checking without it.
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Implements synchronized output (DEC mode 2026), previously deferred in renderer-spec §7.8.
When
RuntimeCapabilities.syncOutputis true, each full-screen frame is wrapped in BSU/ESU (CSI ? 2026 h/CSI ? 2026 l) so the terminal presents it as one atomic repaint, which prevents tearing mid-frame.