fix(agent): classify jiter SSE parse failures as retryable (#65147)

[wesleysimplicio]

Summary

A transient provider/network failure (a truncated/corrupted data: SSE
event) surfaces from jiter — the Rust JSON parser the openai SDK
>=1.x uses to parse streamed chunks — as a plain ValueError. The
non-retryable classifier in agent/conversation_loop.py only carves out
json.JSONDecodeError (added for #14271/#14782), so a jiter parse error
still gets misclassified as a local programming bug and aborts on
attempt 1/3 instead of retrying — even though an identical request
retried seconds later succeeds.

Changes

• agent/conversation_loop.py: added _JITER_PARSE_ERROR_RE (matches
  jiter's consistent "... at line N column N" message shape, since it
  has no dedicated exception class) and excluded that shape — only for a
  bare ValueError, not any subclass already covered by other carve-outs
  — from is_local_validation_error.
• tests/run_agent/test_jsondecodeerror_retryable.py: extended the
  existing mirror-predicate test file (same pattern as the [Bug]: JSONDecodeError bypasses retry logic due to ValueError inheritance #14782 and
  Treat NoneType provider shape errors as retryable #33136 carve-outs) with TestJiterParseErrorIsRetryable (positive case,
  a bare unrelated ValueError still aborts, and a JSONDecodeError
  isn't double-matched) and TestAgentLoopSourceHasJiterCarveOut (belt-
  and-suspenders check that the production source actually contains the
  carve-out).

Validation

Command	Result
pytest tests/run_agent/test_jsondecodeerror_retryable.py -q	13 passed
Fail-before (stashed the conversation_loop.py change)	TestAgentLoopSourceHasJiterCarveOut fails as expected — carve-out absent
Pass-after (restored the change)	13 passed
pytest tests/run_agent/ -q -k "retryable or jsondecode or jiter" --ignore=tests/run_agent/test_strip_reasoning_tags_cli.py	16 passed
ruff check agent/conversation_loop.py tests/run_agent/test_jsondecodeerror_retryable.py	All checks passed

(test_strip_reasoning_tags_cli.py is excluded — it fails to collect on
a clean main checkout too, due to a missing local prompt_toolkit
dependency unrelated to this change.)

Closes #65147

[teknium1]

Thanks for tracing this to the local-validation gate. The premise remains valid on current main: agent/conversation_loop.py:3764-3792 still treats a plain ValueError as non-retryable, while #65147 reports the OpenAI-compatible jiter failure in that form.

Problems

• The added at line N column N suffix matcher is not jiter-specific. It will retry any bare local ValueError with that suffix, widening the exception to the local-programming-error rule in agent/conversation_loop.py:3753-3792.
• TestAgentLoopSourceHasJiterCarveOut reads production source via inspect.getsource. AGENTS.md:1370 explicitly bans source-reading tests, and the mirror predicate does not execute the real retry path.

Suggested changes

• Use a verified jiter-specific signature or relevant streaming-path context, and test a same-suffix non-jiter ValueError remains non-retryable.
• Replace the source/mirror coverage with a real loop retry test; tests/run_agent/test_streaming.py:1206-1263 already demonstrates a failing-first-stream, succeeding-second-stream pattern.

Automated hermes-sweeper review.

[wesleysimplicio]

Both fixed:

1. Narrowed _JITER_PARSE_ERROR_RE to require the message start with one of jiter's real, stable error phrases (verified directly against the installed jiter package — EOF while parsing a value/list/string, trailing characters, trailing comma, key must be a string, expected value, invalid type/escape/unicode/length, control character, number out of range, recursion limit exceeded, duplicate field, unknown field — jiter wraps Rust's serde_json parser, whose error templates are this small, stable set), not just the trailing line/column suffix.
2. Replaced the inspect.getsource belt-and-suspenders test with two real tests driving agent.run_conversation() through a mocked client.chat.completions.create: a jiter-shaped ValueError on the first call retries and succeeds on the second; a same-suffix but non-jiter ValueError aborts immediately without retrying.

uv run --extra dev pytest tests/run_agent/test_jsondecodeerror_retryable.py -q
15 passed

Fail-before verified: reverting only the regex to the old bare-suffix version makes the new negative test fail exactly as expected — call_count == 3 (retried twice, should have aborted on attempt 1) instead of 1, with the actual retry log lines confirming the misclassification.

Broader retry-classifier suite: uv run --extra dev pytest tests/run_agent/ -q -k 'retry or retryable or jiter or jsondecode' → 61 passed, no regressions.