chore: remove retired specs and dead code, state the 2026-10-13 focus

fossil-mcp dead-code over src found 72 candidates; 69 are referenced by tests,
__all__ or other modules, 3 are not and are removed (cli._first_source,
pairs._scorable, provider.openrouter._extract_message_content). Eight spec
directories that steering already called retired or superseded leave the tree
(history keeps them, commits named in overview.md): harnessx-removal,
harnessx-self-improving-rulesets, openrouter-sast-harness, learning-harness,
constrained-detector, three-stage-scan, real-world-vfc-slice,
unseen-repo-evaluation. overview.md gets a current-state section: the valid
benchmark numbers, what they say, and the four active lines in order.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

src/openultrasast/cli.py

@@ -1473,13 +1473,6 @@ def _check_obligations(
     return statics, payload, cited
 
 
-def _first_source(root: Path) -> str:
-    from .preprocess import preprocess_repository
-
-    _, targets = preprocess_repository(root)
-    return targets[0].path if targets else "."
-
-
 def _print_improve_outcomes(outcomes: list[RoundOutcome], manifest_path: Path, target: Path, ledger_path: Path, *, dry_run: bool) -> None:
     print(f"manifest={manifest_path}")
     print(f"target={target}")

src/openultrasast/pairs.py

@@ -1168,11 +1168,6 @@ def _mechanisms(case: PairCase) -> tuple[str, ...]:
 # --- metrics ---------------------------------------------------------------
 
 
-def _scorable(outcomes: Sequence[PairOutcome]) -> tuple[PairOutcome, ...]:
-    """Rows that could be scored. An unscorable row leaves every rate rather than counting as a miss (Req 4.1)."""
-    return tuple(item for item in outcomes if item.unscorable is None)
-
-
 def _metrics(outcomes: Sequence[PairOutcome]) -> PairCorpusMetrics:
     pairs = len(outcomes)
     detected = sum(1 for item in outcomes if item.detected_vuln)

src/openultrasast/provider/openrouter.py

@@ -226,10 +226,3 @@ def _extract_message(payload: object) -> dict[str, object]:
     if not isinstance(message, dict):
         raise OpenRouterError("OpenRouter choice did not include a message")
     return message
-
-
-def _extract_message_content(payload: object) -> str:
-    content = _extract_message(payload).get("content")
-    if not isinstance(content, str) or not content.strip():
-        raise OpenRouterError("OpenRouter message content was empty")
-    return content