fix(action): tighten provider error detection and propagate agent error events (#580)

* fix(action): tighten provider error detection and propagate agent error events

Both bugs from #562:

1. detectProviderError used substring matches against "429", "rate limit",
   etc. — false-positives on commit SHAs containing 429 and on x-ratelimit-*
   response headers in dumped 401 error JSON. rewrote with anchored regexes:
   numeric status codes only match adjacent to a recognised status key, and
   `\brate[_ ]limit(?=[_ ]|\b)` rejects ratelimit-* headers (no separator).
   word-boundary anchors on INTERNAL / UNAVAILABLE / quota / limit:0 reject
   INTERNAL_SERVER_ERROR / time_limit:0 substrings. added 11-case regression
   test.

2. opencode 401s slipped through `eventCount === 0 && lastProviderError`
   because opencode's own type=error event increments eventCount before
   the guard runs. added an explicit `error:` handler that captures the
   event and propagates it to a non-success AgentResult. opencode emits
   the message under `error.data.message`, not the top level. mirror fix
   in claude.ts: error_max_turns / error_during_execution / any error*
   subtype on the result event now flips success: false.

* fix(action): match quota inside identifiers like insufficient_quota

\bquota\b missed insufficient_quota / quota_exceeded / quotaExceeded
because _ is a word character and camelCase has no boundary. quota is
specific enough to be matched as a plain substring.

* fix(action): match `rate limited` and `rate limits exceeded`

Drop the trailing `(?=[_ ]|\b)` lookahead from the rate-limit regex. The
lookahead failed when `limit` was followed by another word character
(`limited`, `limits`), so `rate limited` and `rate limits exceeded` were
slipping past detection. The leading `\b` plus `[_ ]` separator already
rejects `x-ratelimit-*` / `anthropic-ratelimit-*` headers without it.

---------

Co-authored-by: pullfrog[bot] <226033991+pullfrog[bot]@users.noreply.github.com>
Co-authored-by: David Blass <david@arktype.io>

utils/providerErrors.ts

@@ -1,18 +1,38 @@
-const PROVIDER_ERROR_PATTERNS = [
-  { pattern: "429", label: "rate limited (429)" },
-  { pattern: "RESOURCE_EXHAUSTED", label: "quota exhausted" },
-  { pattern: "quota", label: "quota error" },
-  { pattern: "status: 500", label: "provider 500 error" },
-  { pattern: "INTERNAL", label: "provider internal error" },
-  { pattern: "status: 503", label: "provider unavailable (503)" },
-  { pattern: "UNAVAILABLE", label: "provider unavailable" },
-  { pattern: "rate limit", label: "rate limited" },
-  { pattern: "limit: 0", label: "zero quota" },
+type ProviderErrorPattern = { regex: RegExp; label: string };
+
+// status codes are only treated as provider errors when they are adjacent to
+// a recognised status key. this rejects commit SHAs that happen to contain
+// "429", version strings, file hashes, etc.
+const statusKey = `\\b(?:status[_ ]?code|http[_ ]?status|status)["']?\\s*[:=]\\s*["']?`;
+
+const PROVIDER_ERROR_PATTERNS: ProviderErrorPattern[] = [
+  { regex: new RegExp(`${statusKey}429\\b`, "i"), label: "rate limited (429)" },
+  { regex: new RegExp(`${statusKey}500\\b`, "i"), label: "provider 500 error" },
+  { regex: new RegExp(`${statusKey}503\\b`, "i"), label: "provider unavailable (503)" },
+  // matches `rate limit`, `rate limited`, `rate limits exceeded`,
+  // `rate_limit_error`, `rate_limit_exceeded`. the leading `\b` + `[_ ]`
+  // separator rejects `x-ratelimit-*` / `anthropic-ratelimit-*` response
+  // headers (no separator between "rate" and "limit") which routinely
+  // appear in dumped 401 / 4xx error JSON.
+  { regex: /\brate[_ ]limit/i, label: "rate limited" },
+  { regex: /\bRESOURCE_EXHAUSTED\b/, label: "quota exhausted" },
+  // Google gRPC `INTERNAL` status. word-boundary anchors reject
+  // `INTERNAL_SERVER_ERROR` (HTTP 500 message that may appear in unrelated
+  // log lines) and identifiers like `INTERNALS`.
+  { regex: /\bINTERNAL\b/, label: "provider internal error" },
+  { regex: /\bUNAVAILABLE\b/, label: "provider unavailable" },
+  // matches `quota`, `insufficient_quota`, `quota_exceeded`, `quotaExceeded`.
+  // word-character lookarounds would reject `_quota` / `quotaX`; `quota` is
+  // specific enough that a plain substring match is safe.
+  { regex: /quota/i, label: "quota error" },
+  // explicit zero-quota response, e.g. `{"limit": 0}`. the `\b` anchor
+  // around `limit` rejects keys like `time_limit` or `field_limit`.
+  { regex: /["']?\blimit\b["']?\s*:\s*0\b/, label: "zero quota" },
 ];
 
 export function detectProviderError(text: string): string | null {
   for (const entry of PROVIDER_ERROR_PATTERNS) {
-    if (text.includes(entry.pattern)) return entry.label;
+    if (entry.regex.test(text)) return entry.label;
   }
   return null;
 }