acp_thread: Await Tree-sitter parsing before building agent panel diffs#49101
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benbrandt merged 1 commit intozed-industries:mainfrom Feb 16, 2026
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Wait for `parsing_idle()` after `set_language()` in both `Diff::finalized()` and `PendingDiff::finalize()` so that syntax highlighting is available when excerpts are created, fixing missing highlights for multiline strings. Co-Authored-By: Claude <noreply@anthropic.com>
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rtfeldman
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Feb 17, 2026
…fs (#49101) ## Summary Fixes #48684 - Await `parsing_idle()` after `set_language()` in both `Diff::finalized()` and `PendingDiff::finalize()` so that tree-sitter parsing completes before buffer snapshots are taken for excerpts - Without this, the 1ms sync parse timeout almost always expires for non-trivial files, causing excerpts to be created with empty syntax trees and missing syntax highlighting ## Root Cause When the agent panel creates or finalizes a diff, it creates a new `Buffer`, calls `set_language()` (which triggers async tree-sitter parsing), then immediately proceeds to take buffer snapshots and create excerpts **without waiting for parsing to complete**. The sync parse timeout is only 1ms in production (`buffer.rs:1138`), so large files almost always fail the sync parse and fall back to async parsing — but no one awaits the async parse before building the diff. ## Fix Add `buffer.update(cx, |buffer, _| buffer.parsing_idle()).await` after `set_language()` in both code paths (`Diff::finalized()` and `PendingDiff::finalize()`). This is the same pattern already used in `buffer_diff.rs:1728-1731`. ## Test plan - [x] `cargo test -p acp_thread` — all relevant tests pass - [x] `./script/clippy` — no warnings - [x] Manual test: open agent panel, ask it to generate a Python file with multiline strings (`"""`), verify syntax highlighting is correct after diff is finalized Release Notes: - Fixed missing syntax highlighting for multiline strings in agent panel diffs
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Summary
Fixes #48684
parsing_idle()afterset_language()in bothDiff::finalized()andPendingDiff::finalize()so that tree-sitter parsing completes before buffer snapshots are taken for excerptsRoot Cause
When the agent panel creates or finalizes a diff, it creates a new
Buffer, callsset_language()(which triggers async tree-sitter parsing), then immediately proceeds to take buffer snapshots and create excerpts without waiting for parsing to complete. The sync parse timeout is only 1ms in production (buffer.rs:1138), so large files almost always fail the sync parse and fall back to async parsing — but no one awaits the async parse before building the diff.Fix
Add
buffer.update(cx, |buffer, _| buffer.parsing_idle()).awaitafterset_language()in both code paths (Diff::finalized()andPendingDiff::finalize()). This is the same pattern already used inbuffer_diff.rs:1728-1731.Test plan
cargo test -p acp_thread— all relevant tests pass./script/clippy— no warnings"""), verify syntax highlighting is correct after diff is finalizedRelease Notes:
🤖 Generated with Claude Code