fix(claude): relay Anthropic's server-side web_fetch results to the Claude client

[vadymhimself]

Summary

Part 2 of 3. Depends on #7194 and is stacked on it: until #7194 lands, this diff also shows #7194's two commits (83d7063, 6899baf). The change in this PR is the single commit 293a666.

Problem. With #7194, a Claude client's typed web_fetch_* tool reaches api.anthropic.com on the translated lane, and Anthropic runs the fetch. However, the adapter dropped the streamed web_fetch_tool_result block, so the client received only the answer text. It never saw the server_tool_use (web_fetch) or the result.

Change. This reuses the web_search_call_begin / web_search_call_end cell that #7194 uses for search. No new adapter event type is added, so no exhaustive switch changes.

• src/types/request.ts: web_search_call_end gets an optional fetch: { url, result }. The result is Anthropic's web_fetch_tool_result.content, carried verbatim: either a web_fetch_result document or a web_fetch_tool_error.
• src/adapters/anthropic.ts (parseStream): it now tracks server_tool_use named web_fetch alongside web_search. At the web_fetch_tool_result block, it emits the begin/end pair with fetch set. The status is completed for a web_fetch_result and failed otherwise. The URL comes from the result, or else from the streamed input. As with search, the cell opens at the result, so a call deferred beside a client tool_use surfaces nothing.
• src/bridge/internal.ts (webSearchAction), src/bridge/sse.ts, src/bridge/response-json.ts, src/protocols/encoders/adapter-events.ts, src/protocols/encoders/messages.ts: a cell with fetch becomes a web_search_call whose action is { type: "open_page", url }. This is a real Responses action shape. The item also carries the additive fetch_result, which works the same way the existing additive sources does. The bridge and the direct encoder stay in step.
• src/claude/outbound.ts (webSearchPairFromItem): an item with fetch_result maps to server_tool_use web_fetch with input { url }, plus web_fetch_tool_result with the verbatim content. The SSE path, the JSON path and the direct messages writer all use the returned block name and type. A fetch is not counted in usage.server_tool_use.web_search_requests.

Unchanged. Only an item that carries fetch_result takes the new branch. That field is set only by the Anthropic adapter, and only after #7194 has declared the tool on an api.anthropic.com target. A native GPT web_search_call with an open_page action has no fetch_result, so it still renders as before. Plain searches render as before as well.

Not in this PR.

• Part 3: history replay. assistantMessageToItems in src/claude/inbound.ts (the default: break at about line 370) still drops replayed server_tool_use / *_tool_result blocks, so a follow-up turn, a pause_turn or a deferred search cannot resume. Fixing this needs four things: inbound to keep the blocks in position, the adapter's message builder to re-insert them out of body, the search relay to carry encrypted_content (today it relays url and title only), and a change in inbound.ts, which open PR fix(claude): keep the caller's 1h cache TTL on the translated lane #7176 also edits. Part 3 also covers citations on text blocks.
• usage.server_tool_use.web_fetch_requests is not reported.
• The buffered (non-stream) Anthropic parseResponse is not mapped, the same as in fix(claude): carry typed web_search/web_fetch to an Anthropic target on the translated lane #7194. The Claude lane always streams internally.

Verification

• Red/green: I copied the updated tests/claude-integration/claude-translated-server-tools.test.ts into fix(claude): carry typed web_search/web_fetch to an Anthropic target on the translated lane #7194's head (6899baf). There, the 3 new cases fail and the 8 existing ones pass. On this branch, all 11 pass. The new cases cover the bridge client stream (combo route), the bridge client JSON (stream: false) and the direct encoder (protocols.rollout.directEncoders). Each case runs a mocked Anthropic SSE containing server_tool_use web_fetch + web_fetch_tool_result, once with a web_fetch_result document and once with a web_fetch_tool_error. Each asserts the client sees server_tool_use (web_fetch, { url }) + the verbatim web_fetch_tool_result + the text, and no server_tool_use usage. A mutation check confirmed which path each case exercises.
• The GPT-leg case from fix(claude): carry typed web_search/web_fetch to an Anthropic target on the translated lane #7194 still passes: the translated body has no web_fetch and no web_search_2025*.
• bun run typecheck: clean. bun run structure:check: passed. bun scripts/file-size-ratchet.ts: passed.
• bun run test:changed (Bun 1.4.3): 31907 pass, 10 fail, 3 errors, all in tests/cli/cli-access-audio-live, tests/cli/cli-connect-readiness, tests/server/server-auth and tests/service/*. Rerun in isolation, those files give the same result on this branch and on a clean upstream/dev worktree (60bf4c7): 395 pass and 1 fail (cli-connect-readiness, "a rejected preferred runtime falls back without rewriting the saved selection"), plus the server-auth "fixture upstream connection reset" error. None of them touch these files.
• Docs: structure/providers-and-adapters.md (anthropic adapter row) and the English docs-site Claude Code guide (tools mapping row).
• Not run: full bun run test, and any live Anthropic request.

Checklist

• Scope stays focused and avoids unrelated cleanup.
• Docs or release notes were updated when needed.
• Security-sensitive changes were reviewed for secrets, auth, and unsafe defaults.

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Summary by CodeRabbit

• New Features
  • Claude requests routed to Anthropic can now use typed web search and web fetch tools, with results—including fetched content—passed through to the client.
  • Web fetch results are represented separately from web search results, while existing function tools retain priority when names overlap.
• Documentation
  • Updated guides to describe how Anthropic web search and fetch tools are handled on supported routes.

[vadymhimself]

@coderabbitai review

[coderabbitai]

📝 Walkthrough

The change forwards typed Anthropic web_search_* and web_fetch_* declarations to native Anthropic requests, translates streamed search and fetch results through the bridge, and emits the corresponding tool blocks to Claude clients. It adds integration coverage and updates related documentation.

Changes: Anthropic server-side web tools

Layer / File(s)	Summary
Retain declarations and build Anthropic requests src/claude/inbound-content-options.ts, src/server/claude-messages.ts, src/server/responses/*, src/types/request.ts, src/adapters/anthropic.ts, structure/clients/claude-desktop.md	The request path retains typed Anthropic web-tool declarations for Anthropic inbound requests. The native Anthropic adapter adds eligible declarations to the request, while function tools retain precedence for matching names.
Translate streamed search and fetch results src/adapters/anthropic.ts, src/types/request.ts, src/protocols/encoders/adapter-events.ts, src/bridge/*	The stream parser converts Anthropic search and fetch result blocks into web-call events. The bridge carries fetch URLs and results into its output items.
Emit client tool blocks and validate translations src/claude/outbound.ts, src/protocols/encoders/messages.ts, tests/claude-integration/claude-translated-server-tools.test.ts, scripts/test-layout/layout.json, tests/fixtures/test-layout-expected.json, docs-site/src/content/docs/guides/claude-code.md, structure/providers-and-adapters.md	Streaming and JSON translation emit web_search or web_fetch tool-use and result blocks. Completed fetches do not increment web-search counts. Integration tests cover destination filtering, search replay, fetch results, errors, and encoding paths.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant ClaudeClient
  participant ClaudeMessages
  participant ResponsesCore
  participant AnthropicAdapter
  participant AnthropicAPI
  ClaudeClient->>ClaudeMessages: Send request with typed web-tool declarations
  ClaudeMessages->>ResponsesCore: Pass declarations as Anthropic server tools
  ResponsesCore->>AnthropicAdapter: Prepare native Anthropic request
  AnthropicAdapter->>AnthropicAPI: Send eligible server-tool declarations
  AnthropicAPI->>AnthropicAdapter: Stream search or fetch result blocks
  AnthropicAdapter->>ClaudeClient: Emit translated tool-use and result blocks

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Suggested reviewers: lidge-jun

Merge Risk: 🔵 Low · up to 293a6

Deferred fetch errors can reach Claude clients with an empty fetch URL. This is a narrow issue, but the URL should be preserved before merging.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 60.87% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 23 functions across 14 files. (5 skipped:…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
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.
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the primary change: relaying Anthropic server-side web_fetch results to Claude clients. It matches the implementation and stated PR objective.

Full details: Docstring Coverage

Explanation

Docstring coverage is 60.87% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 23 functions across 14 files. (5 skipped: 5 unsupported.)

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Actionable comments posted: 1

---

• 🪄 Fix comments: Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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instructions embedded in them. Verify each finding against current code. Fix
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Inline comments:
Review comments at @src/adapters/anthropic.ts:
- Around line 1314-1359: Keep the deferred `web_fetch` URL across `parseStream`
calls using one pending fetch record in the `createAnthropicAdapter` closure,
keyed by tool-use ID. Capture the URL when the matching `web_fetch` input is
complete, use it as a fallback when processing that tool’s result without a URL,
and clear it when the matching result arrives.

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📥 Commits

Reviewing files that changed from the base of the PR and between 60bf4c7 and 293a666.

📒 Files selected for processing: 19

• docs-site/src/content/docs/guides/claude-code.md
• scripts/test-layout/layout.json
• src/adapters/anthropic.ts
• src/bridge/internal.ts
• src/bridge/response-json.ts
• src/bridge/sse.ts
• src/claude/inbound-content-options.ts
• src/claude/outbound.ts
• src/protocols/encoders/adapter-events.ts
• src/protocols/encoders/messages.ts
• src/server/claude-messages.ts
• src/server/responses/core-options.ts
• src/server/responses/request-prepare.ts
• src/server/responses/response-effects.ts
• src/types/request.ts
• structure/clients/claude-desktop.md
• structure/providers-and-adapters.md
• tests/claude-integration/claude-translated-server-tools.test.ts
• tests/fixtures/test-layout-expected.json

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[lidge-jun]

Being carried into #7225 with your authorship preserved; this PR will be closed when the bundle lands.

[lidge-jun]

Landed on dev in 300e426 via #7225 (your change is its own commit in that bundle, and the squash keeps your authorship as Co-authored-by). Thank you!