fix: detect quota exhaustion from stream; map to BUDGET_EXCEEDED not FAILED

When claude hits the 5-hour usage limit it exits 1. execOnce was
returning the generic "exit status 1" error, hiding the real cause from
the retry loop and the task state machine.

Fix:
- execOnce now surfaces streamErr when it indicates rate limiting or
  quota exhaustion, so callers see the actual message.
- New isQuotaExhausted() detects "hit your limit" messages — these are
  not retried (retrying a depleted 5h bucket wastes nothing but is
  pointless), and map to BUDGET_EXCEEDED in both execute/executeResume.
- isRateLimitError() remains for transient throttling (429/overloaded),
  which continues to trigger exponential backoff retries.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/internal/executor/claude.go b/internal/executor/claude.go
index b97f202..c04a747 100644
--- a/internal/executor/claude.go
+++ b/internal/executor/claude.go
@@ -189,6 +189,11 @@ func (r *ClaudeRunner) execOnce(ctx context.Context, args []string, workingDir s
 		if exitErr, ok := waitErr.(*exec.ExitError); ok {
 			e.ExitCode = exitErr.ExitCode()
 		}
+		// If the stream captured a rate-limit or quota message, return it
+		// so callers can distinguish it from a generic exit-status failure.
+		if isRateLimitError(streamErr) || isQuotaExhausted(streamErr) {
+			return streamErr
+		}
 		return fmt.Errorf("claude exited with error: %w", waitErr)
 	}