[rudycelekli]

Issue for this PR

Closes #44092

Type of change

• Bug fix

What does this PR do?

Include the JSON-escaped raw provider finish reason in unknown-finish errors when it is available. Keep the existing message when absent, and preserve classification and retry behavior.

How did you verify your code works?

• Actual SessionRunner regression covers raw values, quotes/newlines, an empty string, and absent metadata; verifies the thrown error, stored assistant error, projection replay, and retry decision. Three failures before the fix; 40 repeated focused passes after.
• Source-bound Linux qualification: strict baseline oracle, focused tests, full Core suite, Core typecheck, and root bun run check pass.

Screenshots / recordings

No visual UI change; errors and stored/replayed results are asserted directly.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

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Added by the opencode bot (AI-generated).

Related: #34835, #44695

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

[opencode-agent]

Looks correct. The new tests fail on the base for the three cases with a raw finish reason and pass with this change. The full session-runner.test.ts (233 tests) and the packages/core typecheck pass. Classification (incomplete-stream) and retry behaviour are unchanged, and the test checks that the retry hook still sees retry: true.

Public API: unchanged (only the error message text changes).

One gap worth a follow-up or a small addition here: compaction builds the same InvalidProviderOutputError in packages/core/src/session/compaction.ts (around line 549) and still drops the raw value (event.reason.raw). An unknown finish during compaction will still show the generic message.

Also note that #54713 edits the same lines in step.ts, so whichever lands second will need a rebase. It formats its raw reason as (x) rather than : "x", so it would be good to settle on one format.

Related: #34835, #44695