fix(mcp): raise output_schema_hint_bytes default to 1024 and fix stub event name#3106
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fix(mcp): raise output_schema_hint_bytes default to 1024 and fix stub event name#3106
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… event name The 512-byte default caused stub fallback for most real-world MCP tool schemas, making forward_output_schema largely ineffective at default config. Raised default to 1024 in zeph-config and both LLM backend struct defaults. The WARN emitted on the budget-exceeded path used event="mcp.output_schema.forwarded_to_llm", implying the real schema was forwarded when only a stub was sent. Changed to event="mcp.output_schema.stub_used" in openai and claude backends so operators can distinguish the two paths in telemetry and log search. Added 6 unit tests: default value assertion in zeph-config, boundary tests for schema-fits vs stub path in openai and claude. Closes #3084, #3087
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Summary
output_schema_hint_bytesdefault from 512 → 1024 bytes, fixing silent stub fallback for most real-world MCP tool schemas whenforward_output_schema = true(fix(mcp): default output_schema_hint_bytes=512 too small — most real-world MCP tool schemas use stub fallback #3084)mcp.output_schema.forwarded_to_llmtomcp.output_schema.stub_usedin openai and claude backends, making telemetry unambiguous (fix(mcp): output_schema WARN emits event=mcp.output_schema.forwarded_to_llm when stub is used, not schema #3087)Files changed
crates/zeph-config/src/channels.rs—default_output_schema_hint_bytes()512 → 1024, doc comment updatedcrates/zeph-llm/src/openai/mod.rs— struct default + event name fixcrates/zeph-llm/src/openai/tests.rs— 2 new boundary testscrates/zeph-llm/src/claude/mod.rs— struct default + event name fixcrates/zeph-llm/src/claude/tests.rs— 2 new boundary testsTest plan
cargo nextest run --config-file .github/nextest.toml --workspace --lib --bins— 8177 tests passcargo +nightly fmt --check— cleancargo clippy --workspace --lib --bins -- -D warnings— cleanevent="mcp.output_schema.stub_used"in WARN log with Todoist MCP connectedCloses #3084, #3087