[robertn702]

Fixes #81

What changed

• Conservative fallback. ctx.provider.transform placeholders now advertise input: ["text"], output: ["text"] instead of the hard-coded ["text", "image"]. An alias keeps this until ctx.model.transform resolves its source, or forever if the source never resolves. Such an alias rejects every request anyway. This is documented in docs/behavior.md.
• Source capabilities. ctx.model.transform now copies capabilities (tools, input, output) from editor.get(providerID, modelID) explicitly, with fresh arrays. An alias therefore accepts PDFs or images exactly when its source does.
• Changeset: patch for @reasoning-router/opencode.

Root-cause note

Before this change, the ...source spread in ctx.model.transform already copied the source's capabilities, but only implicitly. The hard-coded list applied only to placeholders and to aliases whose source failed to resolve. The new PDF-capable and text-only tests pass on main too. Only the placeholder test fails without this change.

For the setup in the issue, the wrapped sources are config-defined (anthropic-proxy/*). They declare no capabilities, so OpenCode gives them its default ["text", "image"], and the source models themselves also reject PDFs. In OpenCode 2.0.28, opencode api GET /api/model reports ["text","image"] for both anthropic-proxy/claude-opus-5-5 and reasoning-router/claude-opus-5-5.

To get PDFs through, a config-defined source must declare them, for example:

"capabilities": { "input": ["text", "image", "pdf"] }

Sources from the models.dev catalog (for example openai/gpt-6-astra, which reports ["text","image","pdf"]) already declare PDF support.

Wire path

PDF parts are forwarded unchanged. The Anthropic rewrite only pins model, output_config, and thinking and inserts effort updates; it never rewrites user content blocks. New tests:

• core: a document block (base64 PDF with cache_control) is unchanged through ResponsesRouter.prepare, including on a lineage-replayed second turn.
• opencode: an Anthropic document block and a Responses input_file reach the upstream fetch unchanged.
• proxy: an Anthropic document block reaches a real HTTP upstream unchanged.

Verification

• npm run check: typecheck, lint, and tests pass (36 files, 476 tests). One lint warning is pre-existing, in packages/classifiers/test/jev.test.ts.
• With the plugin-v2.ts change reverted, only "registers text-only placeholders and keeps them for an unresolved source" fails.

Summary by CodeRabbit

• New Features
  • Router aliases now inherit their source model’s input and output capabilities. Unresolved sources advertise text-only capabilities.
• Bug Fixes
  • PDF attachments and document details are preserved when messages are forwarded to upstream models, including during conversation replay.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: ae67f1fb-47c5-463c-a668-f6cdbbc17f34

📥 Commits

Reviewing files that changed from the base of the PR and between defe328 and 3519281.

📒 Files selected for processing: 6

• .changeset/alias-source-capabilities.md
• docs/behavior.md
• packages/core/test/wire-anthropic.test.ts
• packages/opencode/src/plugin-v2.ts
• packages/opencode/test/plugin-v2.test.ts
• packages/proxy/test/server.test.ts

Included review availability: This review used your included allowance. Your plan provides up to 1 included review per hour; 0 remain after this review.

📝 Walkthrough

Router aliases now copy input and output capabilities from resolved source models and use text-only capabilities before resolution. Tests cover capability selection and PDF forwarding through Anthropic and OpenAI paths, including Anthropic lineage replay.

Changes: Alias capabilities and PDF forwarding

Layer / File(s)	Summary
Propagate source capabilities packages/opencode/src/plugin-v2.ts, packages/opencode/test/plugin-v2.test.ts, docs/behavior.md, .changeset/alias-source-capabilities.md	Resolved aliases copy the source model’s input and output capabilities. Tests cover PDF-capable, text-only, and unresolved sources. The behavior documentation and changeset describe the capability behavior.
Test PDF forwarding and replay packages/opencode/test/plugin-v2.test.ts, packages/core/test/wire-anthropic.test.ts, packages/proxy/test/server.test.ts	Tests check that PDF document and file parts reach provider requests unchanged. The Anthropic wire test also checks that lineage replay preserves the original document block.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~15 minutes

Change: Bug fix · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 35192

No actionable issue remains in the supplied evidence; this change is mergeable after normal checks.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		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 1 functions across 4 files. (2 skipped: 2 …	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: OpenCode router aliases now advertise capabilities inherited from wrapped source models.
Linked Issues check		Issue #81 coding requirements are met. packages/opencode/src/plugin-v2.ts registers text-only placeholders, then copies source capabilities with fresh input and output arrays when the source r…
Out of Scope Changes check		The reviewed changes stay within issue #81. The plugin change implements capability propagation and the conservative fallback. The OpenCode, core, and proxy tests verify capability advertising and unc…

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 1 functions across 4 files. (2 skipped: 2 unsupported.)

• Fix all pre-merge checks with AI

✨ Finishing Touches: 💡 1

📝 Generate docstrings: 💡

• Commit to this branch
• Create a new PR

🧪 Generate unit tests (beta)

• Commit to this branch
• Create a new PR

• Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}