[tiliakoos]

Problem

A CSV or TSV attachment labelled binary/octet-stream or application/unknown opens as raw text with no table, while the same file labelled application/octet-stream gets the table. #29360 moved binaryPreviewKind and officePreviewKind to GENERIC_MIME_TYPES but missed filePreviewDelimiter, so it now disagrees with filePreviewKind, which treats these labels as generic.

Change

filePreviewDelimiter uses the same GENERIC_MIME_TYPES set. As in #29360, the set also holds video/mp2t and video/vnd.dlna.mpeg-tts, so a .csv under those labels gets a table too; that follows from reusing the set and adds no formats. Specific MIME types still win. Name-only callers are unchanged.

Scope and approval

Very small fix for an obvious bug: one guard reuses the shared set its two siblings already moved to in #29360, with no new formats, settings or UI.

There is no user report behind this. I found no real source that labels a CSV this way. The MCP upload (AttachmentUpload.ts:117) and guest upload (guestAttachments.ts:117) paths and the composer keep whatever label they are given, so one could arrive, but the case for this change is that the helpers should agree.

Verification

• vp test run packages/shared/src/delimitedPreview.test.ts: the new test fails on main (expected null to be ',') and passes here. vp run check:changed upstream/main passes.
• Real client: the web dev client on an empty dev database, in a real desktop browser. A team.csv File labelled binary/octet-stream went through the composer's file input and was sent in a free Replay thread. The stored attachment kept "mimeType":"binary/octet-stream".
• Opening that same stored attachment from its chip shows raw text with main's delimitedPreview.ts swapped back in, and the table (3 rows, 3 columns) on this branch.

Before	After

Not checked: the label was set by hand on the File, so this does not show that any real picker sends it. In the client I ran only a CSV under binary/octet-stream; TSV and application/unknown are covered by the unit test. I ran web only. Desktop was not run, and mobile shares this helper in attachmentDocument.ts and ZipArchiveView.tsx but was not run either. Repo-wide checks were not run.

Claude Opus 5.5 via T3 Code

[macroscopeapp]

Approvability

Verdict: Approved at 9a3c2ce

Macroscope's review found this PR approvable — CSV and TSV attachments with generic MIME labels now retain their table preview through the existing filename fallback. The change is confined to preview classification, with explicit MIME handling and parsing limits unchanged.

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[coderabbitai]

No actionable comments were generated in the recent review.

Walkthrough

filePreviewDelimiter now accepts generic MIME types through GENERIC_MIME_TYPES. Tests check comma selection for CSV files and tab selection for TSV files with generic MIME types.

Changes: Delimited preview MIME handling

Layer / File(s)	Summary
Delimiter MIME guard and tests packages/shared/src/delimitedPreview.ts, packages/shared/src/delimitedPreview.test.ts	filePreviewDelimiter now uses GENERIC_MIME_TYPES to check MIME types. Tests verify delimiter selection for .csv and .tsv files with generic MIME types.

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Possibly related PRs

• pingdotgg/t3code#27372: Adds MIME types to GENERIC_MIME_TYPES, which filePreviewDelimiter now uses.
• pingdotgg/t3code#29360: Applies a similar GENERIC_MIME_TYPES guard to other preview-kind functions.

Suggested labels: size:XS

Suggested reviewers: macodev00, maria-rcks

Merge Risk: Minimal · up to 9a3c2

Generic-labeled CSV and TSV attachments retain table previews without overriding explicit MIME classifications.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly and concisely describes the main change: preserving CSV and TSV table previews under generic MIME types.
Description check		The description includes all required sections. It explains the problem, implementation, scope rationale, focused verification, observed results, limitations, and agent details.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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Recent review info

Run configuration

• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: main
• File: .coderabbit.config.ts
• Commit: 647bd14
• Layers: Repository TS config
• Review profile: CHILL
• Plan: Advanced
• Run ID: f70f20c5-09d0-4ef3-a496-d6c3766b2b6c

Commits

Reviewing files that changed from the base of the PR and between 647bd14 and 9a3c2ce.

Files selected for processing: 2

• packages/shared/src/delimitedPreview.test.ts
• packages/shared/src/delimitedPreview.ts

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 8 remain after this review.

[maria-rcks]

Note

Written by gpt-6.1-sol on behalf of Maria

Verified in a real dev environment

verified unchanged head 9a3c2ce184937dd87ab7999c2a91b3ebaf88ba3e on linux with the real dev web client, repository playwright, /usr/bin/google-chrome, and real codex gpt-6.1-sol turns. no replay provider or mocked server.

reproduced first on github/main at e68e19d605 in a separate worktree after vp i. created a project pointing to that git checkout through the app. uploaded matching csv and tsv data through the composer's actual file input, explicitly supplying the mime labels with playwright. after sending, opened the persisted attachment chips. both generic-mime files showed source only on main. stopped main before starting the exact pr head, also after vp i, with isolated dev state copied from this task's main run. the same stored attachments now show two-row, three-column tables. a fresh upload and real codex turn on the pr head also succeeded.

runtime observations (persisted message projection opened read-only):

team.csv      binary/octet-stream    59 bytes
team.tsv      application/unknown    59 bytes
ordinary.csv  text/csv               59 bytes
codex response on main: Ada: London / Grace: New York
codex response on PR:   Ada: London / Grace: New York

nearby behavior checked: ordinary text/csv still renders the same table; switching generic csv from table to source and back preserves its contents. a 10.85-second recording of these interactions was reviewed in t3.

blacksmith passed vp test run packages/shared/src/delimitedPreview.test.ts (18 tests) and vp run check:changed 647bd148b3fbd7c8b57a10fd41ae6d5fc7b35cc1 (format, lint, knip, affected typechecks, 19 tests). current ci checks have no failures or pending runs. no code changes were needed.

main, matching csv data:

pr head, matching csv data:

Not verified

native desktop, ios, android, remote/relay/tunnel connections, other providers, and the two video mime labels in the shared generic set were not exercised. these mime labels were explicitly supplied at upload; this does not prove that an operating system picker naturally assigns them. uploaded video playback and seeking were checked in t3's browser player; github's image proxy does not render the external mp4 inline, so only the before/after images are embedded here.