fix(shared): classify workspace previews by literal filenames

[yashranaway]

What Changed

Classify workspace images and browser documents by their literal filename extension, matching the existing video viewer behavior. Authored Markdown and media URLs retain their separate URL-aware parser.

The shared fix covers server asset validation and image search, web and desktop file viewers, mobile file previews, and provider image-read activity.

Why

Workspace previews strip literal # and ? characters as URL suffixes. This rejects files such as assets#archive/icon#v2.png and accepts non-image filenames such as image.png#notes.txt.

Testing

• File preview and video tests pass, 39/39; the new classification regressions fail on main.
• Asset access tests pass, 28/28, including issuing and resolving real workspace URLs while preserving exact image access.
• Shared package typecheck, targeted lint and formatting, and git diff --check pass.
• No UI layout changes or browser testing.

Checklist

• One focused change
• Explained what changed and why
• Added regression coverage for the changed behavior
• No UI layout or animation changes

Model: GPT-6 Astra
Harness: T3 code

Note

Add regression test for workspace asset previews with literal # and ? filenames

Adds an effect-based test in AssetAccess.test.ts that creates workspace files with literal # or ? in their path and verifies issued asset URLs resolve correctly. Also checks rejection of sibling files and filenames with image-like prefixes followed by non-image suffixes.

^{Macroscope summarized f008404.}

[macroscopeapp]

Approvability

Verdict: Approved at f008404

Macroscope's review found this PR approvable — This small, well-tested fix corrects preview classification for literal filenames and folders containing # or ?, without changing schemas, security-sensitive code, or deployment behavior. Existing non-preview suffix cases remain explicitly rejected.

No code changes detected at 188e553. Prior analysis still applies.

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🧰 Additional context used

📚 Code guidelines (1)

docs/internals/effect-services.md — configured

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📥 Commits

Reviewing files that changed from the base of the PR and between 188e553 and 10ede2a.

📒 Files selected for processing (2)

• apps/server/src/assets/AssetAccess.test.ts
• docs/user/composer.md

🚧 Files skipped from review as they are similar to previous changes (1)

• docs/user/composer.md

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📝 Walkthrough

Walkthrough

The preview extension check now evaluates the complete lowercased path. Tests cover preview paths and asset resolution when filenames or directories contain literal # or ? characters. The composer documentation describes extension-based file recognition.

Changes

Workspace preview paths

Layer / File(s)	Summary
Preview extension matching packages/shared/src/filePreview.ts	hasPreviewExtension now checks the complete lowercased path instead of removing query strings and fragments first.
Preview path validation packages/shared/src/filePreview.test.ts, apps/server/src/assets/AssetAccess.test.ts, docs/user/composer.md	Tests cover recognized and rejected preview paths and asset resolution for paths containing literal # or ? characters. The composer documentation describes extension-based recognition for these paths.

Priority: ➖ Normal

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

Change: Bug fix

Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to 10ede

The preview change has no established merge-blocking impact; ACP raw output remains available when a suffixed file URL is not promoted.

Architecture Summary

Architecture risk: 🔵 Low · up to 10ede

The change affects 3 systems.

Changed systems: packages/shared, apps/server, docs

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

• observed — packages/shared (library) was modified; 2 changed files map to changed impact.
• observed — apps/server (service) was modified; 1 changed file maps to changed impact.
• observed — docs (service) was modified; 1 changed file maps to changed impact.

Before / after behavior

• observed — Modified behavior in packages/shared/src/filePreview.test.ts: The recognizes browser preview path %s test case list drops document.pdf?download=1 and adds document#draft.pdf and reports?old/document.pdf.
• observed — Modified behavior in packages/shared/src/filePreview.test.ts: Image preview path cases change vector.svg#mark to vector#mark.svg and add photo?edited.JPEG and images#archive/icon.png, while texture.webp and image.avif remain.
• observed — Modified behavior in packages/shared/src/filePreview.test.ts: The rejects non-preview path %s test retains README.md, src/index.ts, image.png.ts, and png, and adds image.png#notes.txt, image.svg?notes.txt, document.pdf?download=1, report.html#notes.txt, and image%2Epng as additional rejected paths, restructuring the case list into a single-line it.each array.
• observed — Modified behavior in packages/shared/src/filePreview.ts: hasPreviewExtension now lowercases the whole path and tests the extension against it, whereas before it first stripped any ? query or # fragment via split(/[?#]/, 1); URLs or file paths containing a query or fragment no longer match the preview extensions, affecting isWorkspaceBrowserPreviewPath and isWorkspaceImagePreviewPath.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 3 files. (1 skipped: 1 …	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 classifying workspace previews by literal filenames.
Description check	✅ Passed	The description explains the problem, change, and verification. It does not include the template’s scope and approval details, such as a triaged issue or maintainer approval, or why this focused fix n…
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.

Full details: Docstring Coverage

Explanation

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 3 files. (1 skipped: 1 unsupported.)

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[shivamhwp]

Tested on two real Android phones (POCO F4 on Android 14, POCO M3 Pro on Android 13) with the dev client against an isolated server, comparing main with this PR. Each file was opened from an @ mention in the new-thread composer.

assets#archive/icon#v2.png, a real PNG. Main cuts the path at #, treats the file as text, and shows "File unavailable". With this PR it renders the image.

image.png#notes.txt, a text file. Main sees image.png and fails with "Image unavailable: unknown image format". With this PR it shows the text.

I updated the branch with main. filePreview.test.ts and AssetAccess.test.ts pass on the updated head (80/80).

One gap main already has: the mobile Files screen still strips ? and # before the audio check, at apps/mobile/src/features/files/filePath.ts:107. Not blocking, and it can be a follow-up.