fix(deepagents): degrade unsupported binaries in read_file instead of crashing the run

[Kamal Gurbanov (kamaalg)]

Problem

The built-in read_file tool (in createFilesystemMiddleware) returns any non-text binary that isn't image/audio/video as a { type: "file", mimeType, data } content block:

// libs/deepagents/src/middleware/fs.ts (before)
return [{ type: "file", mimeType, data: base64Data }];

For every MIME type except application/pdf, that block cannot be delivered to the model provider:

• Anthropic wraps it as a base64 document, whose media_type must be application/pdf. It returns a hard 400 and the whole turn fails:

  messages.N...tool_result.content.0.document.source.base64.media_type: Input should be 'application/pdf'

• OpenAI and OpenRouter only accept PDF (and images) via input_file, so they reject it too.

So the moment a deep agent reads a .docx / .pptx / .xlsx — or any file that resolves to application/octet-stream — the entire run aborts. This is easy to hit in practice (e.g. an agent documenting a repository that happens to contain office files). It surfaced downstream in openwiki, which uses the stock read_file tool.

Fix

Keep emitting a file block only for application/pdf — the one binary document type accepted across providers — and degrade any other binary to a short text note (path, MIME type, size). The agent gets a model-safe, useful result and continues instead of crashing. As a bonus, this avoids pushing large, unusable base64 blobs into the context window.

Tests

Added a read_file binary handling suite:

• office doc (.pptx) → text note, no file block
• unknown binary (application/octet-stream) → text note
• PDF → still a file block
• image → still an image block

vitest run src/middleware/fs.test.ts → 63 passed, no type errors. oxlint and oxfmt --check clean. Changeset included (deepagents: patch).

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🦋 Changeset detected

Latest commit: 8fe9dc9

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
deepagents	Patch
deepagents-acp	Patch
@deepagents/evals	Patch

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commit: 8fe9dc9