fix(cliproxyapi): detect Anthropic shape on minimal Capy bodies

[NomenAK]

Summary

isAnthropicShape in the CliProxyApi executor missed minimal Anthropic bodies (messages[0].content as a plain string, no system block) and routed them to /v1/chat/completions instead of /v1/messages. The downstream symptom was Anthropic SDK clients receiving an OpenAI Chat Completions response shape and failing to parse.

Strengthen the detector with two more strong signals — top-level thinking field and top-level metadata.user_id — so the minimal-body case is also recognized.

Related Issues

• Closes #
• Related to #
• Follow-up to fix(cliproxyapi): Anthropic-shape body routing and gate compatibility #2165 (Anthropic-shape body routing — initial detector)

Motivation

#2165 introduced the Anthropic-shape detector that routes Capy and other Claude SDK clients to CPA's /v1/messages. The detector required either :

1. body.system !== undefined — Anthropic-only field
2. messages[0].content is array — Anthropic content-block shape

Captured artifact for a minimal /v1/messages Capy call :

clientRawRequest.body = {
  "model": "claude-opus-4-7",
  "max_tokens": 500,
  "stream": false,
  "thinking": { "type": "adaptive", "display": "summarized" },
  "messages": [{ "role": "user", "content": "Dis bonjour." }]
}

• body.system : absent ✗ (Capy omits when no system prompt)
• messages[0].content : string ✗ (Anthropic allows both string and array per API docs)

Both indicators miss. Executor routes to /v1/chat/completions → CPA returns OpenAI Chat Completions shape → Anthropic SDK client sees choices[] instead of content[] and either drops the response or surfaces a parse error.

Changes

open-sse/executors/cliproxyapi.ts — isAnthropicShape adds two strong indicators :

// Top-level `thinking` is Anthropic-only — OpenAI uses `reasoning` / `reasoning_effort`.
// Catches Capy minimal bodies where content is string and no system block exists.
if (b.thinking !== undefined) return true;

// Top-level `metadata.user_id` is the CC wire-image OAuth identifier;
// OpenAI request bodies don't carry it.
if (b.metadata && typeof b.metadata === "object" && (b.metadata as Record<string, unknown>).user_id !== undefined) return true;

Both are decisive ; either alone routes to /v1/messages.

Validation

• Manual : pre-fix Capy minimal body returned chat.completion shape ; post-fix returns proper Anthropic shape with content: [{type:'text', text:'…'}].
• Unit test : new it("does not strip OpenAI-shape bodies (no thinking, no system, string content)") — confirms genuine OpenAI bodies still skip the Anthropic strips when no Anthropic indicators are present.
• All 37 existing CliProxyApi executor tests still pass.

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request updates the CliproxyapiExecutor to improve the detection of Anthropic-specific request bodies by checking for the thinking field and metadata.user_id. The unit tests have been updated to ensure that OpenAI-shaped bodies, including those with reasoning_effort, are correctly handled. I have no feedback to provide.

[NomenAK]

Update after 2026-05-12 empirical bisect (11 variants × 2 turns + 5-turn stress against live Anthropic via CPA cloak):

The detection improvements in this PR (b.thinking, b.metadata.user_id as Anthropic-shape signals) remain valuable for routing — they fix the case of minimal Capy bodies that miss messages[0].content being an array and otherwise get mis-routed to /v1/chat/completions where CPA emits OpenAI-shape SSE that Anthropic SDK clients can't parse.

I'm closing the companion PRs that targeted the strip side-effects of this detection (#2194 mcp_ prose rewrite, #2195 metadata strip): the bisect confirmed Anthropic accepts those fields intact through the CPA cloak, so the strips were over-engineered preemptive defense that silently dropped valid client content. The detection itself (this PR) is orthogonal and stands.

The fork-side cleanup is in NomenAK/OmniRoute@cleanup/remove-over-engineered-strips (commits 4e9e534, 3166060, 4bb93c5) — keeping this PR open as-is for the detection signals.

[diegosouzapw]

Thanks @NomenAK for the focused ClipProxyAPI fix. I synced the PR branch with release/v3.8.0, validated tests/unit/cliproxyapi-executor.test.ts locally, and will include this in the upcoming release.