Best possible solution:

Rebase or refresh onto current main, verify the helper remains unused, and land the deletion once the production TypeScript gate confirms the current merge result is clean.

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

Yes at source and hosted-gate level: an unused private function deterministically triggers the reported TS6133 check, although the failure was not rerun here against the newer current-main SHA.

Is this the best way to solve the issue?

Yes. Deleting an unreachable delegating wrapper while retaining the canonical resolver is the narrowest maintainable fix and avoids adding suppression or compatibility code.

AGENTS.md: found and applied where relevant.

Codex review notes: model internal, reasoning high; reviewed against 260a5c6e2b1f.

Label changes:

• add P2: This is a bounded production type-check regression with no runtime behavior change or urgent user-facing outage.
• 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 internal dead-code cleanup claims no runtime behavior change; the relevant proof is the production TypeScript gate rather than a live Microsoft Teams interaction.

Label justifications:

• P2: This is a bounded production type-check regression with no runtime behavior change or urgent user-facing outage.
• 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 internal dead-code cleanup claims no runtime behavior change; the relevant proof is the production TypeScript gate rather than a live Microsoft Teams interaction.

PR surface:

Source -7. Total -7 across 1 file.

What I checked:

• Compiler failure is concrete: The PR links production type-check job 86793082132 from Actions run 29242903349, which reports TS6133 for the unused helper at line 109. (extensions/msteams/src/attachments/html.ts:109, 1577c285009f)
• Patch is behavior-neutral: The head deletes only a private wrapper whose body delegates directly to resolveMSTeamsInboundAttachmentPresentation(...).placeholder; no canonical resolver or caller behavior is changed. (extensions/msteams/src/attachments/html.ts:109, af0b66a9880d)
• Regression provenance: The helper became private during the merged Microsoft Teams dead-code refactor in refactor(deadcode): trim msteams private exports #106279, but remained in production source without a caller. (extensions/msteams/src/attachments/html.ts:109, 1577c285009f)
• Current-base refresh remains: The PR head is mergeable but based on f167089, while the supplied current-main SHA is 260a5c6; the production type gate should be rerun after refreshing the branch. (260a5c6e2b1f)
• Scoped plugin policy: The repository and extensions/ policies favor private module-local helpers and lean removal of stale wrappers; this deletion stays wholly inside the owning Microsoft Teams plugin. (extensions/AGENTS.md:263, 260a5c6e2b1f)

Likely related people:

• steipete: Authored and merged the immediately preceding Microsoft Teams private-export cleanup that made this helper private, so they have the strongest recent context for the regression and intended cleanup boundary. (role: recent area contributor; confidence: high; commits: 1577c285009f; files: extensions/msteams/src/attachments/html.ts)
• Evizero: Co-authored the earlier Microsoft Teams attachment-handling implementation associated with commit 0f7f7bb, making them relevant to the original attachment presentation behavior preserved by this cleanup. (role: feature introducer; confidence: medium; commits: 0f7f7bb95f; files: extensions/msteams/src/attachments/html.ts, extensions/msteams/src/attachments.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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