[ScriptedAlchemy]

Fixes #4211
Fixes #4210

What was broken

• Both SDKs hand-listed terminal events and omitted unavailable, so a valid unavailable terminal was rejected (Rust: "SSE event name is not canonical") or ignored (TypeScript: stream treated as disconnected).
• The TypeScript reconnect fetch sat outside the retry try/catch, so one failed reconnect ended the generator with budget left. Rust returned the first failed connect() as an error without counting it, never retried mid-stream read failures, and kept the iterator live after the error.

Fix

• TerminalState::ALL and as_str() in tracedecay-tool-catalog are the one list. The Rust SDK's is_terminal_event reads them, and codegen emits OPERATION_TERMINATIONS into the generated types.ts (and OperationTermination derives from it), which client.ts uses. A new server variant now breaks compilation in the exhaustive as_str match and in a unit test.
• Reconnect contract, same in both SDKs: every reconnect attempt, including a failed connect, spends maxReconnects; only transport failures are retried (auth, problem and protocol errors surface at once); the first connection is never retried; the last accepted frontier is kept; after exhaustion one final error is raised, then Rust yields None.

Evidence

• Tests in both languages cover every terminal variant ending the stream with no reconnect, an unavailable terminal with a disagreeing receipt, two dropped reconnects recovering within a budget of 3, exhaustion giving one error then None, first connection not retried, and a 401 on reconnect not retried.
• Mutation: removing unavailable from the terminal list fails the Rust and TypeScript terminal tests; making a failed connect fatal fails the Rust recovery, exhaustion and auth tests; restoring the old TypeScript fetch path fails the recovery and exhaustion tests ("expected 3 requests, got 2").
• Passed: bazel test --config=clippy //crates/tracedecay-sdk/... //crates/tracedecay-tool-catalog/..., rustfmt_check_2024 for the SDK, pnpm --dir sdks/typescript run build|typecheck|test (56 tests), pnpm --dir dashboard run contracts:check. plugin/chatgpt-extension/embedded/server.mjs is rebuilt in each commit.

Not changed: Rust has no reconnect delay or abort signal (blocking client), so the TypeScript retry: delay and abort-during-wait have no Rust counterpart.

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[devin-ai-integration]

Devin Review found 1 potential issue.

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[devin-ai-integration]

🟡 Malformed stream bytes get silently skipped

When SSE contains invalid UTF-8, read_event labels the decode failure as Transport, so next retries it. A successful reconnect can hide the malformed stream and deliver later events as valid.

Learn more

Rust's BufRead::read_line reports invalid UTF-8 as io::ErrorKind::InvalidData. read_event currently converts every such read error into ClientError::Transport. The new retry branch therefore reconnects from the last accepted frontier when stream bytes are malformed. A later valid response can make the iterator complete without reporting that the first response violated SSE encoding.

Example: A stream publishes a valid open with sequence 0 and a resume token, then sends 0xff before any terminal event. With one reconnect allowed, a resumed connection returning completed at sequence 0 makes the iterator return success instead of reporting the invalid UTF-8.

Recommended fix: Distinguish InvalidData from actual I/O failures in read_event, return ClientError::Protocol for malformed UTF-8, and test that an invalid UTF-8 frame never consumes reconnect budget.

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