fix(agent): allow octet stream text reads

[zerob13]

Summary

• allow application/octet-stream files to fall through to plain-text reads instead of binary sniffing
• decode UTF-8 BOM and UTF-16 BOM text correctly in Agent filesystem reads
• keep known archives, WebAssembly, audio, and video blocked while preserving image vision routing
• add regression coverage for UTF-16 diff files detected as octet streams

Tests

• pnpm exec vitest run --config vitest.config.ts test/main/lib/binaryReadGuard.test.ts test/main/tool/agentTools/agentToolManagerRead.test.ts
• pnpm run typecheck
• pnpm run i18n
• pnpm run lint
• pnpm exec oxfmt --check src/main/lib/binaryReadGuard.ts src/main/tool/agentTools/agentFileSystemHandler.ts src/main/tool/agentTools/agentToolManager.ts test/main/lib/binaryReadGuard.test.ts test/main/tool/agentTools/agentToolManagerRead.test.ts

Summary by CodeRabbit

• New Features

  • Improved text-file reading with automatic UTF-8, UTF-16LE, and UTF-16BE detection.
  • Added support for reading code and diff files labeled as application/octet-stream.
  • UTF-16 content is decoded cleanly without unwanted null characters or byte-order marks.

• Bug Fixes

  • Binary, audio, and video files remain blocked from text reads.
  • Image files remain available for vision-based reading.
  • Text and document files are handled more reliably.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 0853fb75-fe09-4d67-9a17-9a4c783a678e

📥 Commits

Reviewing files that changed from the base of the PR and between 5ca2c50 and db4eaba.

📒 Files selected for processing (1)

• test/main/tool/agentTools/agentToolManagerRead.test.ts

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📝 Walkthrough

Walkthrough

The binary read guard now classifies files by MIME type only. Agent file reads support BOM-aware UTF-16LE, UTF-16BE, and UTF-8 decoding. Octet-stream code and diff files are handled as raw text.

Changes

Agent file reading

Layer / File(s)	Summary
MIME guard contract src/main/lib/binaryReadGuard.ts, test/main/lib/binaryReadGuard.test.ts	shouldRejectAgentBinaryRead now accepts a MIME type synchronously. Tests cover allowed octet-stream and image types and rejected binary, audio, and video types.
Read path integration src/main/tool/agentTools/agentToolManager.ts, src/main/tool/agentTools/agentFileSystemHandler.ts, test/main/tool/agentTools/agentToolManagerRead.test.ts	The manager passes only the MIME type to the guard and treats octet-stream content as raw text. readFile decodes BOM-marked UTF-16LE, UTF-16BE, and UTF-8 files. Regression tests cover all three encodings and verify that file preparation is bypassed.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Possibly related PRs

• ThinkInAIXYZ/deepchat#1584: Modifies UTF-8 handling for agent file and command output through different functions and execution paths.

Suggested reviewers: yyhhyyyyyy

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the main change: allowing application/octet-stream files to be read as text by the agent.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/fix-octet-stream-read

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@test/main/tool/agentTools/agentToolManagerRead.test.ts`:
- Around line 224-240: Add focused regression tests alongside the existing
UTF-16LE case for AgentFileSystemHandler.readFile behavior with UTF-16BE and
UTF-8 BOM inputs reported as application/octet-stream. Verify returned content
contains the expected text without a leading BOM or NUL characters, and keep
each case minimal and consistent with the existing manager.callTool setup.

🪄 Autofix

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 6865541d-c736-424f-84fd-54d3e8477023

📥 Commits

Reviewing files that changed from the base of the PR and between 443d3b8 and 5ca2c50.

📒 Files selected for processing (5)

• src/main/lib/binaryReadGuard.ts
• src/main/tool/agentTools/agentFileSystemHandler.ts
• src/main/tool/agentTools/agentToolManager.ts
• test/main/lib/binaryReadGuard.test.ts
• test/main/tool/agentTools/agentToolManagerRead.test.ts

[yyhhyyyyyy]

LGTM