fix(codex): consolidate repeated Responses namespaces

[matt1060338871-pixel]

Summary / 概述

Fix native Responses requests rejected with Duplicate namespace name 'mcp__...' after Codex discovers tools in the same namespace more than once, including inherited conversation history.

Root Cause and Scope

Codex retains separate tool_search_output records. OpenCode Go's native Responses gateway registers their namespace declarations request-wide and rejects repeated names. The shared third-party Responses preparer forwarded those declarations unchanged. Its passthrough is traceable to 1fda7d1dafa564481df2fbc717e9c96225da7937 (August 30); this is evidence of a compatibility gap, not proof that that commit introduced the observed regression. The existing namespace-flattening adapter is xAI-specific and should not be broadened for this different error.

This patch runs in the shared production/probe Responses preparer, gated by parsed URLs for OpenCode Go (opencode.ai/zen/go/v1) and direct DeepSeek (api.deepseek.com). Live before/after verification was performed against OpenCode Go; the direct DeepSeek gate has unit/contract coverage and a separately reported matching failure, but was not live-tested with direct DeepSeek credentials.

What Changed

• Consolidate compatible repeated namespaces across top-level tools and immediate input[].tool_search_output.tools, keeping the union of function declarations at the first occurrence.
• Preserve all discovery call/output records, IDs, status, execution, qualified function names, and ordinary conversation/tool-result content. Later discovery outputs may have an empty tool list, which the tested gateway accepts.
• Deduplicate functions with identical callable contracts, retaining the latest function description. Real inherited GitHub discovery history changed only its appended plugin-attribution text; treating that text as a schema conflict would leave a subsequent duplicate namespace unresolved. If namespace metadata, callable definitions, tool kinds, or shapes conflict, leave that entire namespace group unchanged instead of silently discarding or replacing schemas.
• Keep official/managed routes, other native gateways, and Chat/Anthropic conversion outside this change. No service-name hardcoding, session-file edits, response transformation, or missing-call_id repair.
• Bump the request-preparer fingerprint version so old compatibility receipts do not describe the previous preparation behavior.

Verification

• Fresh synthetic requests sent directly to OpenCode Go, without old conversation state: repeated mcp__hindsight, mcp__websearch, and mcp__codex_apps__plugin_management each returned HTTP 400 before normalization and HTTP 200 after normalization. The executable used the production Rust source, not a Python reimplementation.
• Automatic tool invocation returned HTTP 200 and the expected function_call with namespace: mcp__hindsight, name: read, both for the single-discovery control and normalized repeated discoveries. A normalized request containing prior function-call/output history also returned HTTP 200.
• Explicit forced tool-choice probes were rejected for both single-discovery controls and normalized requests; these are not counted as successful checks or attributed to this patch. Normal automatic tool selection succeeded.
• Local replay of the affected task's discovery declarations plus inherited declarations: two Hindsight namespace declarations became one; all six distinct functions and all four discovery-output records remained. No private conversation content was sent in the synthetic live probes.
• Nine focused unit/contract tests cover union/order/ID preservation, idempotence, top-level collisions, description-only drift, conflict handling, opaque nested data, URL boundaries, runtime/probe parity, and unchanged Chat conversion.
• cargo fmt --check --manifest-path src-tauri/Cargo.toml passed.
• cargo clippy --manifest-path src-tauri/Cargo.toml --lib --no-default-features -- -D warnings passed.

The patched desktop executable was installed locally and restarted without a version bump or public binary release. Four raw, unnormalized requests through the installed localhost proxy passed: repeated Hindsight, websearch, and plugin-management discovery each completed with HTTP 200; automatic tool invocation also completed with the expected qualified function call. The provider-module suite passed all 1,101 tests.

After installation, the user retried the original affected desktop task and confirmed that the conversation recovered. This is user-confirmed original-task recovery in addition to the installed-proxy tests above. An earlier CLI resume attempt was blocked locally by the desktop's active-writer lock and did not send an upstream request. No conversation history or writer locks were modified.

Related Issue / 关联 Issue

N/A. User-reported native Responses failure; intentionally separate from malformed delegation outputs missing call_id.

Screenshots / 截图

N/A: protocol-only change. Reproduction and before/after evidence are described above without exposing private task history.

Checklist / 检查清单

• pnpm typecheck passes / Not run: no frontend changes.
• pnpm format:check passes / Not run: Rust formatting checked separately.
• Rust library Clippy passes with -D warnings; full application/binary Clippy was not run.
• No user-facing text changed; i18n changes are not applicable.