Auto-reset Claude session on context-window overflow (prompt too long)

A resumed Claude session that grew past the model's context limit failed
every turn with "Prompt is too long" — even auto-compaction could not
shrink it — so the same oversized session was reused indefinitely and the
channel looped forever on that error (no Claude reset pattern matched,
unlike Codex). Add "prompt is too long" / context-limit patterns to
SESSION_RESET_PATTERNS so the poisoned session is cleared and the next
turn starts fresh.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/session-recovery.test.ts

@@ -60,6 +60,26 @@ describe('shouldResetSessionOnAgentFailure', () => {
       }),
     ).toBe(true);
   });
+
+  it('resets the session on context-window overflow (prompt too long)', () => {
+    expect(
+      shouldResetSessionOnAgentFailure({
+        result: null,
+        error:
+          'API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"prompt is too long: 215000 tokens > 200000 maximum"}}',
+      }),
+    ).toBe(true);
+  });
+
+  it('resets the session when max_tokens exceeds the context limit', () => {
+    expect(
+      shouldResetSessionOnAgentFailure({
+        result:
+          'input length and `max_tokens` exceed context limit: 190000 + 20000 > 200000',
+        error: undefined,
+      }),
+    ).toBe(true);
+  });
 });
 
 describe('shouldRetryFreshSessionOnAgentFailure', () => {

src/session-recovery.ts

@@ -9,6 +9,12 @@ const SESSION_RESET_PATTERNS = [
   /400[^\n]*thinking/i,
   /thinking[^\n]*block[^\n]*(?:invalid|error|signature)/i,
   /invalid[^\n]*signature[^\n]*thinking/i,
+  // Context-window overflow: the resumed session has grown past the model's
+  // limit, so even auto-compaction fails with "Prompt is too long". Without
+  // this, the same oversized session is reused every turn and the channel
+  // loops forever on the same error. Drop it so the next turn starts fresh.
+  /prompt is too long/i,
+  /input length and .*exceed context limit/i,
 ];
 
 const SESSION_RETRY_PATTERNS = [