fix(router): stop protecting passing build/test output as error traces

headroom/transforms/error_detection.py

@@ -145,6 +145,17 @@ def content_has_error_indicators(text: str) -> bool:
     return bool(_rust_content_has_error_indicators(text))
 
 
+# Success-summary phrases from common build/test/lint tools that legitimately
+# pair two indicator keywords (`error` + `fail`) while reporting a PASS, e.g.
+# tsc's "Found 0 errors", jest's "0 failing" / "0 failures", eslint's
+# "0 problems (0 errors, 0 warnings)". Stripped before the keyword scan below
+# so a clean JS/TS toolchain run doesn't get permanently protected from
+# compression for the rest of a long coding session (issue #1696).
+_ZERO_RESULT_PATTERN = re.compile(
+    r"\b(?:0|no)\s+(?:error|errors|failing|failure|failures)\b", re.IGNORECASE
+)
+
+
 def content_has_strong_error_indicators(text: str) -> bool:
     """Stricter triage for compression-protection gates.
 
@@ -162,7 +173,7 @@ def content_has_strong_error_indicators(text: str) -> bool:
     safe — downstream compressors (LogCompressor) still preserve
     error lines.
     """
-    lowered = text.lower()
+    lowered = _ZERO_RESULT_PATTERN.sub(" ", text.lower())
     hits = 0
     for keyword in ERROR_INDICATOR_KEYWORDS:
         if keyword in lowered:

tests/test_error_detection.py

@@ -0,0 +1,38 @@
+"""Regression tests for the error/importance detection triage helpers."""
+
+from __future__ import annotations
+
+from headroom.transforms.error_detection import content_has_strong_error_indicators
+
+
+def test_real_error_output_is_detected() -> None:
+    text = "Traceback (most recent call last):\n  ...\nValueError: fatal error during load"
+    assert content_has_strong_error_indicators(text)
+
+
+def test_single_keyword_mention_is_not_flagged() -> None:
+    # Only one distinct indicator keyword ("error") — should not trip the
+    # two-keyword threshold.
+    text = 'Wrote error_handler.py with an "errors": [] field.'
+    assert not content_has_strong_error_indicators(text)
+
+
+def test_tsc_passing_summary_is_not_flagged() -> None:
+    # Regression for issue #1696: a clean `tsc` run mentions both "error"
+    # and (via "0 failures" in a paired test run) "fail" while reporting
+    # success. Previously this tripped the two-keyword heuristic and got
+    # the message permanently protected from compression.
+    text = "Found 0 errors. Watching for file changes.\nTests: 0 failures, 42 passed"
+    assert not content_has_strong_error_indicators(text)
+
+
+def test_eslint_passing_summary_is_not_flagged() -> None:
+    text = "0 problems (0 errors, 0 warnings)\nno failing tests"
+    assert not content_has_strong_error_indicators(text)
+
+
+def test_zero_result_phrase_does_not_mask_a_real_second_error() -> None:
+    # "0 errors" is stripped, but a genuine second distinct indicator
+    # elsewhere in the same blob must still trigger protection.
+    text = "0 errors from linter, but the build crashed with a fatal signal"
+    assert content_has_strong_error_indicators(text)