copilot_harness.cjs was treating Copilot quota exhaustion as generic partial execution, repeatedly retrying with --continue until retry budget was exhausted. This change classifies the observed quota error as non-retryable and exits early with explicit diagnostics.

• Quota exhaustion classification (narrow match)

  • Added CAPI_QUOTA_EXCEEDED_PATTERN and isCAPIQuotaExceededError(output) to detect_agent_errors.cjs (the generic harness error detection module), alongside the existing inference access, MCP policy, timeout, and model-not-supported detectors.
  • Wired capiQuotaExceededError into detectErrors() return value and writeOutputs() (emits capi_quota_exceeded_error GitHub Actions output).
  • copilot_harness.cjs imports isCAPIQuotaExceededError from detect_agent_errors.cjs instead of defining it locally.

• Retry-loop behavior update

  • Wired quota detection into the main retry decision path.
  • Added quota state to attempt diagnostics (isCAPIQuotaExceededError=...).
  • Inserted an early non-retryable branch before generic partial-execution retry logic:
    • logs attempt N: Copilot quota exceeded — not retrying
    • avoids --continue retries for quota exhaustion.

• Test coverage updates

  • Added focused detection tests in detect_agent_errors.test.cjs (exact message, embedded message, spacing variants, case-insensitive, negative cases).
  • Updated all detectErrors() tests to assert on the new capiQuotaExceededError field.
  • Updated retry-policy unit helper in copilot_harness.test.cjs to call isCAPIQuotaExceededError() directly instead of duplicating the pattern inline.

const isQuotaExceeded = isCAPIQuotaExceededError(result.output);

if (isQuotaExceeded) {
  log(`attempt ${attempt + 1}: Copilot quota exceeded — not retrying`);
  break;
}