fix: isolate hidden pane render cadence

[akbash-bot]

Summary

• separate hidden-only render attempts from the presentation cadence
• wake the server when visible PTY or terminal-title work joins pending hidden output
• preserve bounded hidden-output coalescing and pre-index render targets before source classification
• add cadence, mixed-source, and title-wake regression coverage

Checks

• release A/B/A, 100 samples: idle total/output p50 6.49/5.51 ms; hidden tab at 400 lines/s 6.17/5.38 ms; idle again 6.01/5.20 ms (before: hidden 14.61/13.42 ms vs idle 6.65/5.53 ms)
• cargo nextest run --locked -E 'all() - test(live_server_holds_one_pty_master_fd_per_pane)' --no-fail-fast (3468 passed; excluded test also fails on clean origin/master in this VPS environment)
• focused cadence, mixed-source, title-wake, hidden reveal, static visibility, and direct-observer tests
• cargo clippy --all-targets --locked -- -D warnings
• just windows-lint
• just ui-hot-path-architecture-test
• integration asset, plugin marketplace, and maintenance script suites
• just bench-render-scale (1/15/50 ratios unchanged within noise; final background 1.00/1.12/1.12, active 1.00/1.24/1.43)

refs #2890

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 53cb37cf-51f5-49c1-8522-0062271506b4

📥 Commits

Reviewing files that changed from the base of the PR and between 2427163 and 9322859.

📒 Files selected for processing (4)

• docs/next/CHANGELOG.md
• src/app/mod.rs
• src/app/runtime.rs
• src/server/headless.rs

🚧 Files skipped from review as they are similar to previous changes (3)

• docs/next/CHANGELOG.md
• src/app/mod.rs
• src/server/headless.rs

Included review availability: Your plan includes up to 10 reviews per rolling hour; 6 remain after this review.

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📝 Walkthrough

Walkthrough

The render system now tracks render attempts separately from presentation attempts. Source-aware signals and render-target visibility allow visible PTY, graphics, title, and full-render work to bypass hidden-tab render cadence.

Changes

Presentation cadence and visibility

Layer / File(s)	Summary
Separate render and presentation cadence src/app/mod.rs, src/app/runtime.rs	App stores separate render and presentation timestamps. Runtime methods record every render attempt and update presentation timing only for presented frames.
Source-aware render wakeups src/render_signal.rs	PTY and terminal-title requests report newly added sources while preserving duplicate-request coalescing. Tests cover the updated wakeup behavior.
Visible presentation selection src/server/headless.rs, docs/next/CHANGELOG.md	Headless rendering identifies visible presentation work, includes direct terminal targets, reuses render plans, and records presentation status. A changelog entry documents the behavior.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to 93228

This change isolates hidden-pane rendering while preserving visible updates and wake-up behavior, with focused regression coverage and reported checks passing; no actionable merge-blocking risk remains beyond normal review.

Possibly related PRs

• herdrdev/herdr#2523: Both changes update graphics-driven rendering and visibility-aware presentation handling in src/server/headless.rs.
• herdrdev/herdr#2627: Both changes update render-signal and headless-rendering logic for terminal-title and PTY presentation cadence.

Sequence Diagram(s)

sequenceDiagram
  participant RenderSignal
  participant HeadlessRenderLoop
  participant AppRuntime
  participant VisibleTerminal
  RenderSignal->>HeadlessRenderLoop: report pending visible work
  HeadlessRenderLoop->>AppRuntime: check presentation cadence
  AppRuntime-->>HeadlessRenderLoop: allow or defer presentation
  HeadlessRenderLoop->>VisibleTerminal: render visible frame
  HeadlessRenderLoop->>AppRuntime: record render attempt and presentation status

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🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description clearly explains the render-cadence changes, wake-up behavior, regression coverage, and validation results.
Title check	✅ Passed	The title concisely and accurately summarizes the main change: isolating hidden-pane render cadence.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

✨ 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 akbash/2890-hidden-pane-latency

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[greptile-apps]

Greptile Summary

The PR separates hidden-only PTY render attempts from presentation cadence so hidden panes cannot delay visible terminal work.

• Adds independent render-attempt and presentation timestamps.
• Wakes pending coalesced work when a newly added PTY or terminal-title source may be visible.
• Pre-classifies pending render sources against full-app and direct-terminal targets.
• Adds regression coverage for hidden cadence, mixed-source wakeups, and terminal-title work.

Confidence Score: 5/5

The PR appears safe to merge with no concrete blocking or independently actionable non-blocking issues identified.

The new cadence split preserves bounded hidden-output processing while allowing visible PTY, title, generic, graphics, and full-render work to use the independent presentation cadence.

Important Files Changed

Filename	Overview
src/app/mod.rs	Adds and initializes the presentation timestamp and records ordinary app renders as presentation attempts.
src/app/runtime.rs	Introduces independent presentation-cadence checks and centralized render-attempt accounting, with focused cadence coverage.
src/render_signal.rs	Makes newly coalesced PTY and terminal-title sources wake the consumer and adds allocation-free pending-source predicates.
src/server/headless.rs	Classifies pending work against connected render targets and permits presentation work to bypass hidden-only render cadence.
docs/next/CHANGELOG.md	Documents the foreground-input latency fix.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  R[Pending render request] --> C{Normal render cadence due?}
  C -->|Yes| T[Take coalesced request]
  C -->|No| P{Presentation cadence due?}
  P -->|No| W[Wait for deadline or notification]
  P -->|Yes| V{Pending presentation work?}
  V -->|No: hidden PTY only| W
  V -->|Yes: visible PTY, title, generic, graphics, or full| T
  T --> L{Retained render plan}
  L -->|Hidden PTY| H[Record render attempt only]
  L -->|Presentation-capable plan| S[Render or stream]
  S --> A[Record render and presentation attempt]

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