fix: honor droid scrollback clear requests in panes

[factory-ain3sh]

Description

What: Honor Droid's scrollback-clear requests so replaying a primary-screen transcript does not retain duplicate welcome headers and stale rows. The process-aware regression fails on current master with two headers and passes with this change.

Why: Herdr's Droid-specific filter strips ESC[3J and ESC[?3J before they reach the terminal parser. Clearing the visible screen still works, but the old scrollback survives beneath the replayed content. Filtering also depends on where PTY chunks split the escape sequence.

How: Remove the filter and pass the original PTY bytes to the existing parser and trackers. The vendored parser already implements the screen/history boundaries; no new rendering logic is needed.

Related Issue

No linked GitHub issue.

Reviewer Guide

1. src/pane/osc.rs: removes the process-specific filter and tests that enforced suppression.
2. src/pane/terminal.rs: passes unmodified bytes through the existing write path, eliminating the extra foreground-process lookup for ED3.
3. src/pane/terminal/migration_tests.rs: extends the existing harness with a real foreground process identifying as droid; checks replay across whole writes, bytewise writes, seven-byte chunks, and every split within the erase prefix.

Risk & Impact

Droid can now clear primary-screen history when it explicitly requests ED3, rather than retaining that history. ED2 still preserves scrollback, ED3 preserves the visible screen, and alternate-screen clearing leaves the saved primary screen intact. Manual clear-pane handling is unchanged. No dependencies, persistence, or protocol changes.

Verification

Behavior verified @ 0fe2b62b: two 55-line frames replayed into a 24-row terminal leave one welcome header and no old-frame rows, both at the bottom and when scrolled up.

• Sentinel test: primary_screen_replay_honors_ed3_for_droid_at_chunk_boundaries, observed failing on original production code and passing after the fix.
• erase_display_preserves_screen_and_history_boundaries passes for both clear sequences.
• Standard validators: just ci 'test(pane::terminal::)' passed: formatting, Clippy on all targets, 148 pane-terminal tests, 144 maintenance tests, six architecture tests, and 44 Bun tests. Commit hooks also passed.
• Not tested here: macOS, Windows, the full Rust suite, or a fresh interactive Droid UI run. Native Linux regression coverage includes real PTY foreground-process detection.

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📥 Commits

Reviewing files that changed from the base of the PR and between 5a64914 and 0fe2b62.

📒 Files selected for processing (3)

• src/pane/osc.rs
• src/pane/terminal.rs
• src/pane/terminal/migration_tests.rs

💤 Files with no reviewable changes (1)

• src/pane/osc.rs

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📝 Walkthrough

Walkthrough

The change removes Droid-specific scrollback-clear filtering from OSC handling and PTY processing. Scrollback-clear sequences now pass through unchanged, and terminal trackers inspect the original PTY bytes. Migration tests can provide a foreground process ID and cover ED3 behavior across complete, bytewise, and split writes, including primary-screen, alternate-screen, ED2, and ED3 cases.

Suggested reviewers: ogulcancelik

Priority: ➖ Normal

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 9 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: allowing Droid scrollback-clear requests in panes.
Description check	✅ Passed	The description directly explains the Droid scrollback-clear issue, the implementation, regression coverage, validation, and known test limitations.
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.

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[greptile-apps]

Confidence Score: 5/5

The PR appears safe to merge; the raw-byte path restores standard ED3 handling and is covered across relevant screen and chunk-boundary cases.

Summary

This PR removes the Droid-specific ED3 suppression so original PTY bytes consistently reach the terminal parser and associated trackers.

• Removes process-name detection and scrollback-clear filtering from the OSC helpers.
• Eliminates the foreground-process lookup from the terminal write path.
• Adds regression coverage for both ED3 forms across whole, bytewise, fixed-size, and split writes.
• Verifies primary-screen history clearing, visible-screen preservation, and alternate-screen isolation.

Diagram

sequenceDiagram
  participant P as PTY process
  participant T as Pane terminal
  participant O as Sequence trackers
  participant G as Ghostty parser
  participant S as Screen and history
  P->>T: Original PTY bytes, including ED3
  T->>O: Observe unmodified bytes
  T->>G: Write unmodified bytes
  G->>S: Apply ED3 screen/history boundaries
  S-->>T: Preserve display and clear applicable scrollback

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_{Reviews (1) · Last reviewed commit: "fix: honor droid scrollback clear reques..."}

[JJLiebig]

Approved, tested the current master binary against this PR head with a fresh Droid session. Droid’s /clear leaves one welcome header, removes stale transcript and shell rows, and resets scrollback to zero. The model and Herdr lifecycle hook continued working normally.

Only note: I tested this with a the cli-proxy-api since I don't have a factory sub. But I see no reason why this should change the outcome.

[factory-ain3sh]

Approved, tested the current master binary against this PR head with a fresh Droid session. Droid’s /clear leaves one welcome header, removes stale transcript and shell rows, and resets scrollback to zero. The model and Herdr lifecycle hook continued working normally.

Only note: I tested this with a the cli-proxy-api since I don't have a factory sub. But I see no reason why this should change the outcome.

Ty! Yup, no difference in TUI whether you use direct or byok