Best possible solution:

Refresh the branch onto current main and land the focused assertions without production changes, preserving terminal-core as owner of complete ANSI parsing and the gateway renderer as owner of residual control filtering.

Do we have a high-confidence way to reproduce the issue?

Yes. Current main implements C1 filtering in renderTerminalBufferText, while its owning focused test lacks C1 sequence, range, and boundary assertions.

Is this the best way to solve the issue?

Yes. Extending the existing owning test with exhaustive boundary cases is the narrowest maintainable solution and avoids production churn or a duplicate harness.

AGENTS.md: found and applied where relevant.

Codex review notes: model internal, reasoning high; reviewed against 6eb9a5ada23b.

Label changes:

• add P3: This is a small, test-only reliability improvement that protects existing behavior without runtime or upgrade impact.
• add rating: 🦞 diamond lobster: Overall readiness is 🦞 diamond lobster; proof is 🌊 off-meta tidepool and patch quality is 🦞 diamond lobster.
• add status: 👀 ready for maintainer look: ClawSweeper has no concrete contributor-facing blocker left for this PR. Not applicable: This maintainer-labeled PR changes only regression tests and no runtime behavior; its exact-head focused Testbox and changed-check results are the appropriate evidence.

Label justifications:

• P3: This is a small, test-only reliability improvement that protects existing behavior without runtime or upgrade impact.
• rating: 🦞 diamond lobster: Overall readiness is 🦞 diamond lobster; proof is 🌊 off-meta tidepool and patch quality is 🦞 diamond lobster.
• status: 👀 ready for maintainer look: ClawSweeper has no concrete contributor-facing blocker left for this PR. Not applicable: This maintainer-labeled PR changes only regression tests and no runtime behavior; its exact-head focused Testbox and changed-check results are the appropriate evidence.

PR surface:

Tests +8. Total +8 across 1 file.

What I checked:

• Current-main coverage gap: Current main tests ESC-based ANSI, carriage returns, BEL/tab handling, and OSC, but has no C1 sequence, exhaustive C1 range, or adjacent Unicode boundary assertion. (src/gateway/terminal/buffer-text.test.ts:4, 6eb9a5ada23b)
• Renderer ownership: The renderer delegates complete escape-sequence stripping to terminal-core and then removes residual C0/C1 controls while preserving tabs and handling CR/LF separately. (src/gateway/terminal/buffer-text.ts:21, 6eb9a5ada23b)
• C1 dependency contract: Terminal-core explicitly recognizes U+009B CSI sequences with parameter bytes and a final byte, matching the added U+009B31m and U+009B0m input. (packages/terminal-core/src/ansi.ts:3, 6eb9a5ada23b)
• User-facing caller: The terminal.text gateway method returns renderTerminalBufferText output directly, so the focused helper test protects the owning plain-text projection. (src/gateway/server-methods/terminal.ts:271, 6eb9a5ada23b)
• Patch comparison: The PR adds only a complete C1 CSI assertion and an exhaustive residual-range boundary test; current main contains neither the PR head nor equivalent assertions. (src/gateway/terminal/buffer-text.test.ts:5, 66af5346ef50)
• Runtime-fix provenance: Commit a3f9f35 added the C1 range to the renderer; its merged discussion identified terminal-core as owner of complete ANSI sequences, which is the boundary covered by this follow-up. (src/gateway/terminal/buffer-text.ts:9, a3f9f3567f71)

Likely related people:

• steipete: He performed the land-ready review and squash merge for the runtime C1 filter, is a co-author of that landed commit, and is assigned to this paired follow-up. (role: merger and recent area contributor; confidence: high; commits: a3f9f3567f71; files: src/gateway/terminal/buffer-text.ts, src/gateway/terminal/buffer-text.test.ts)
• lsr911: They authored the merged runtime change that extended terminal buffer filtering through the C1 range protected by this test. (role: introduced behavior; confidence: high; commits: a3f9f3567f71; files: src/gateway/terminal/buffer-text.ts)

• 🦀 challenger crab: rare, exceptional readiness with strong proof, clean implementation, and convincing validation.
• 🦞 diamond lobster: very strong readiness with only minor maintainer review expected.
• 🐚 platinum hermit: good normal PR, likely mergeable with ordinary maintainer review.
• 🦐 gold shrimp: useful signal, but proof or patch confidence is still limited.
• 🦪 silver shellfish: thin signal; proof, validation, or implementation needs work.
• 🧂 unranked krab: not merge-ready because proof is missing/unusable or there are serious correctness or safety concerns.
• 🌊 off-meta tidepool: rating does not apply to this item.

Shiny media proof means a screenshot, video, or linked artifact directly shows the changed behavior. Runtime, network, CSP, and security claims still need visible diagnostics.

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