IB-WP-0020-T05: shadow-mode CLI flags; close IB-WP-0020

Add --shadow-baseline <id> and --shadow-rate <float> opt-in flags to
generate run, generate resume, and generate from-source. When
--shadow-baseline names a candidate id from the routing config,
build_routing_policy_from_config wraps every other candidate in an
llm-connect ShadowingAdapter using that baseline plus a
PairedGrader(ExactMatchJudge()) and the workspace-resolved
QualityLedger. The baseline candidate itself is never wrapped — that
would shadow it against itself. --shadow-rate defaults to 0.1 when
--shadow-baseline is set; passing --shadow-rate without
--shadow-baseline fails fast with shadow_rate_without_baseline.
Setting --shadow-baseline without a ledger_path in the config fails
with missing_routing_ledger_for_shadow so observations have a place to
land before any call goes out.

run_generation grew shadow_baseline + shadow_rate kwargs and
_adapter_for("routing", ...) plumbs them into
build_routing_policy_from_config. The wrapped ShadowingAdapter slots
into the policy's prefer/fallback per task type via a
(candidate_id, task_type) reverse lookup, and adapters_by_id on the
adaptive policy gets the string-keyed entries.

Five new tests cover: shadow_rate without baseline fails fast, shadow
mode without a ledger fails fast, unknown shadow baseline id fails
fast, structural assertion that ShadowingAdapter wraps non-baseline
candidates and leaves the baseline raw, and a behavioural check that
shadow_rate=1.0 calls the baseline on every call while shadow_rate=0.0
skips entirely. Test forces async_shadow=False so the call counter is
deterministic.

Closes IB-WP-0020: T01-T05 all done. Workplan status flips from active
to finished. 179 tests pass, 2 skipped (both live OpenRouter smokes).

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

src/infospace_bench/cli.py

@@ -208,6 +208,8 @@ def build_parser() -> argparse.ArgumentParser:
     generate_run.add_argument("--fixture-responses", default="")
     generate_run.add_argument("--routing-config", default="", help="YAML routing config (required with --provider routing)")
     generate_run.add_argument("--quality-floor", type=float, default=None, help="Override the config's default_quality_floor for this run")
+    generate_run.add_argument("--shadow-baseline", default="", help="Candidate id from the routing config to use as the shadow-grading baseline")
+    generate_run.add_argument("--shadow-rate", type=float, default=None, help="Shadow sampling rate 0..1 (default 0.1 when --shadow-baseline is set)")
     generate_run.add_argument("--resume", action="store_true")
     generate_run.add_argument("--force", action="store_true")
 
@@ -222,6 +224,8 @@ def build_parser() -> argparse.ArgumentParser:
     generate_resume.add_argument("--fixture-responses", default="")
     generate_resume.add_argument("--routing-config", default="")
     generate_resume.add_argument("--quality-floor", type=float, default=None)
+    generate_resume.add_argument("--shadow-baseline", default="")
+    generate_resume.add_argument("--shadow-rate", type=float, default=None)
     generate_resume.add_argument("--force", action="store_true")
 
     generate_status = generate_sub.add_parser(
@@ -245,6 +249,8 @@ def build_parser() -> argparse.ArgumentParser:
     generate_from_source.add_argument("--fixture-responses", default="")
     generate_from_source.add_argument("--routing-config", default="", help="YAML routing config (required with --provider routing)")
     generate_from_source.add_argument("--quality-floor", type=float, default=None)
+    generate_from_source.add_argument("--shadow-baseline", default="")
+    generate_from_source.add_argument("--shadow-rate", type=float, default=None)
     generate_from_source.add_argument("--max-chunks", type=int, default=0)
     generate_from_source.add_argument(
         "--chapter",
@@ -559,6 +565,8 @@ def main(argv: list[str] | None = None) -> int:
                         fixture_responses=args.fixture_responses or None,
                         routing_config=args.routing_config or None,
                         quality_floor=args.quality_floor,
+                        shadow_baseline=args.shadow_baseline or None,
+                        shadow_rate=args.shadow_rate,
                         resume=args.resume,
                         force=args.force,
                     ).to_dict()
@@ -573,6 +581,8 @@ def main(argv: list[str] | None = None) -> int:
                         fixture_responses=args.fixture_responses or None,
                         routing_config=args.routing_config or None,
                         quality_floor=args.quality_floor,
+                        shadow_baseline=args.shadow_baseline or None,
+                        shadow_rate=args.shadow_rate,
                         resume=True,
                         force=args.force,
                     ).to_dict()
@@ -601,6 +611,8 @@ def main(argv: list[str] | None = None) -> int:
                         fixture_responses=args.fixture_responses or None,
                         routing_config=args.routing_config or None,
                         quality_floor=args.quality_floor,
+                        shadow_baseline=args.shadow_baseline or None,
+                        shadow_rate=args.shadow_rate,
                     )
                     _write_json(result.to_dict())
                 else:

src/infospace_bench/generator.py

@@ -429,6 +429,8 @@ def run_generation(
     fixture_responses: str | Path | None = None,
     routing_config: str | Path | None = None,
     quality_floor: float | None = None,
+    shadow_baseline: str | None = None,
+    shadow_rate: float | None = None,
     resume: bool = False,
     force: bool = False,
 ) -> GenerationRunResult:
@@ -457,6 +459,8 @@ def run_generation(
             fixture_responses=fixture_responses,
             routing_config=routing_config,
             quality_floor=quality_floor,
+            shadow_baseline=shadow_baseline,
+            shadow_rate=shadow_rate,
             workspace=_workspace_for(root_path),
         )
         if workflow_ids
@@ -562,6 +566,8 @@ def _adapter_for(
     fixture_responses: str | Path | None,
     routing_config: str | Path | None = None,
     quality_floor: float | None = None,
+    shadow_baseline: str | None = None,
+    shadow_rate: float | None = None,
     workspace: Path | None = None,
 ) -> AssistedGenerationAdapter:
     if fixture_responses:
@@ -582,7 +588,12 @@ def _adapter_for(
         )
 
         config = load_routing_config(routing_config)
-        policy = build_routing_policy_from_config(config, workspace=workspace)
+        policy = build_routing_policy_from_config(
+            config,
+            workspace=workspace,
+            shadow_baseline_id=shadow_baseline,
+            shadow_rate=shadow_rate,
+        )
         effective_floor = (
             quality_floor
             if quality_floor is not None

src/infospace_bench/routing_config.py

@@ -287,6 +287,8 @@ def build_routing_policy_from_config(
     workspace: str | Path | None = None,
     env: Mapping[str, str] | None = None,
     adapter_factory: AdapterFactory | None = None,
+    shadow_baseline_id: str | None = None,
+    shadow_rate: float | None = None,
 ) -> Any:
     """Materialise a parsed config into a live llm-connect routing policy.
 
@@ -302,20 +304,92 @@ def build_routing_policy_from_config(
 
     Fails fast (before any network call) when a candidate's required API
     key env var is missing from ``env``.
+
+    When ``shadow_baseline_id`` is set, every non-baseline candidate is
+    wrapped in an llm-connect ``ShadowingAdapter`` using the named
+    baseline candidate plus a PairedGrader(ExactMatchJudge()) and the
+    QualityLedger from ``config.ledger_path``. ``shadow_rate`` controls
+    the sampling fraction (defaults to 0.1). The baseline candidate
+    itself is never wrapped — that would shadow it against itself.
     """
     from llm_connect.routing import AdaptiveRoutingPolicy, RoutingPolicy, RoutingRule
 
     environment: Mapping[str, str] = env if env is not None else os.environ
     factory: AdapterFactory = adapter_factory or _default_adapter_factory
 
+    if shadow_rate is not None and shadow_baseline_id is None:
+        raise InfospaceError(
+            "shadow_rate_without_baseline",
+            "shadow_rate requires shadow_baseline_id; pass --shadow-baseline with --shadow-rate",
+            {"shadow_rate": shadow_rate},
+        )
+
+    use_adaptive = (
+        config.default_quality_floor is not None
+        or any(task.quality_floor is not None for task in config.task_types)
+        or config.ledger_path is not None
+        or shadow_baseline_id is not None
+    )
+
+    ledger = _resolve_ledger(config, workspace, required=shadow_baseline_id is not None)
+
+    raw_adapters: dict[str, Any] = {}
+    for task in config.task_types:
+        for candidate in task.candidates:
+            if candidate.id not in raw_adapters:
+                raw_adapters[candidate.id] = factory(candidate, environment)
+
+    baseline_adapter = None
+    if shadow_baseline_id is not None:
+        if shadow_baseline_id not in raw_adapters:
+            raise InfospaceError(
+                "missing_shadow_baseline",
+                f"shadow_baseline_id {shadow_baseline_id!r} not declared as a candidate in the routing config",
+                {"shadow_baseline_id": shadow_baseline_id},
+            )
+        baseline_adapter = raw_adapters[shadow_baseline_id]
+
     adapters_by_id: dict[str, Any] = {}
+    if shadow_baseline_id is None:
+        adapters_by_id = dict(raw_adapters)
+    else:
+        # Wrap each candidate (per task) in a ShadowingAdapter unless it *is* the baseline.
+        from .routing import wrap_with_shadow_sampling
+        from llm_connect.grading import ExactMatchJudge, PairedGrader
+
+        assert ledger is not None  # _resolve_ledger raised if required and missing
+        grader = PairedGrader(judge=ExactMatchJudge())
+        effective_rate = shadow_rate if shadow_rate is not None else 0.1
+        for task in config.task_types:
+            for candidate in task.candidates:
+                key = (candidate.id, task.task_type)
+                if candidate.id == shadow_baseline_id:
+                    adapters_by_id[candidate.id] = raw_adapters[candidate.id]
+                    continue
+                # One ShadowingAdapter per (candidate, task_type) pair so the
+                # task_type tagged on observations matches the rule it serves.
+                shadow_id = f"shadow:{candidate.id}@{task.task_type}"
+                adapters_by_id[shadow_id] = wrap_with_shadow_sampling(
+                    candidate=raw_adapters[candidate.id],
+                    baseline=baseline_adapter,
+                    grader=grader,
+                    ledger=ledger,
+                    task_type=task.task_type,
+                    adapter_id=candidate.id,
+                    baseline_adapter_id=shadow_baseline_id,
+                    shadow_rate=effective_rate,
+                    async_shadow=True,
+                )
+                adapters_by_id[key] = adapters_by_id[shadow_id]  # task-keyed reverse lookup
+
     rules: list[RoutingRule] = []
     for task in config.task_types:
-        candidates: list[Any] = []
+        candidates = []
         for candidate in task.candidates:
-            if candidate.id not in adapters_by_id:
+            if shadow_baseline_id is not None and candidate.id != shadow_baseline_id:
-                adapters_by_id[candidate.id] = factory(candidate, environment)
+                candidates.append(adapters_by_id[(candidate.id, task.task_type)])
-            candidates.append(adapters_by_id[candidate.id])
+            else:
+                candidates.append(adapters_by_id[candidate.id])
         prefer = candidates[0]
         prefer_candidate = task.candidates[0]
         fallback = candidates[1] if len(candidates) > 1 else None
@@ -328,30 +402,38 @@ def build_routing_policy_from_config(
             )
         )
 
-    use_adaptive = (
-        config.default_quality_floor is not None
-        or any(task.quality_floor is not None for task in config.task_types)
-        or config.ledger_path is not None
-    )
     if not use_adaptive:
         return RoutingPolicy(rules=rules)
 
-    from llm_connect.quality import QualityLedger
+    # Clean adapters_by_id for AdaptiveRoutingPolicy: keep stable string keys only.
-
+    string_keyed = {key: value for key, value in adapters_by_id.items() if isinstance(key, str)}
-    ledger: QualityLedger | None = None
-    if config.ledger_path:
-        ledger_path = Path(config.ledger_path)
-        if not ledger_path.is_absolute() and workspace is not None:
-            ledger_path = Path(workspace) / ledger_path
-        ledger_path.parent.mkdir(parents=True, exist_ok=True)
-        ledger = QualityLedger(path=ledger_path)
     return AdaptiveRoutingPolicy(
         rules=rules,
         ledger=ledger,
-        adapters_by_id=dict(adapters_by_id),
+        adapters_by_id=string_keyed,
     )
 
 
+def _resolve_ledger(
+    config: RoutingConfig, workspace: str | Path | None, *, required: bool
+) -> Any:
+    from llm_connect.quality import QualityLedger
+
+    if not config.ledger_path:
+        if required:
+            raise InfospaceError(
+                "missing_routing_ledger_for_shadow",
+                "Shadow sampling requires a ledger_path in the routing config",
+                {"config_ledger_path": config.ledger_path},
+            )
+        return None
+    ledger_path = Path(config.ledger_path)
+    if not ledger_path.is_absolute() and workspace is not None:
+        ledger_path = Path(workspace) / ledger_path
+    ledger_path.parent.mkdir(parents=True, exist_ok=True)
+    return QualityLedger(path=ledger_path)
+
+
 def _default_adapter_factory(
     candidate: RoutingCandidateConfig, env: Mapping[str, str]
 ) -> Any:

tests/test_routing_config.py

@@ -463,6 +463,187 @@ def test_build_routing_policy_honours_custom_api_key_env() -> None:
     assert isinstance(policy.rules[0].prefer, OpenRouterAdapter)
 
 
+def test_shadow_rate_without_baseline_fails_fast() -> None:
+    from infospace_bench.routing_config import build_routing_policy_from_config
+
+    config = parse_routing_config(MINIMAL)
+    with pytest.raises(InfospaceError) as exc_info:
+        build_routing_policy_from_config(
+            config,
+            shadow_rate=0.5,
+            adapter_factory=_fake_adapter_factory_record([]),
+        )
+    assert exc_info.value.code == "shadow_rate_without_baseline"
+
+
+def test_shadow_baseline_without_ledger_path_fails_fast() -> None:
+    """ShadowingAdapter needs a place to write observations; require ledger_path."""
+    from infospace_bench.routing_config import build_routing_policy_from_config
+
+    config = parse_routing_config(MINIMAL)
+    with pytest.raises(InfospaceError) as exc_info:
+        build_routing_policy_from_config(
+            config,
+            shadow_baseline_id="openrouter:gpt-4o-mini",
+            adapter_factory=_fake_adapter_factory_record([]),
+        )
+    assert exc_info.value.code == "missing_routing_ledger_for_shadow"
+
+
+def test_shadow_baseline_not_in_config_fails_fast(tmp_path: Path) -> None:
+    from infospace_bench.routing_config import build_routing_policy_from_config
+
+    data = {**MINIMAL, "ledger_path": "quality.jsonl"}
+    config = parse_routing_config(data)
+    with pytest.raises(InfospaceError) as exc_info:
+        build_routing_policy_from_config(
+            config,
+            workspace=tmp_path,
+            shadow_baseline_id="not-in-config",
+            adapter_factory=_fake_adapter_factory_record([]),
+        )
+    assert exc_info.value.code == "missing_shadow_baseline"
+
+
+def test_shadow_wraps_candidates_excluding_baseline(tmp_path: Path) -> None:
+    from llm_connect.adapter import LLMAdapter
+    from llm_connect.models import LLMResponse, RunConfig
+    from llm_connect.shadowing import ShadowingAdapter
+    from infospace_bench.routing_config import build_routing_policy_from_config
+
+    data = {
+        "schema_version": 1,
+        "ledger_path": "quality.jsonl",
+        "task_types": {
+            "extract-entities": {
+                "candidates": [
+                    {"id": "candidate-a", "provider": "openrouter", "model": "openai/gpt-4o-mini"},
+                    {"id": "baseline-x", "provider": "claude_code", "model": "claude-opus-4-7"},
+                ],
+            },
+        },
+    }
+    config = parse_routing_config(data)
+
+    class _Stub(LLMAdapter):
+        def __init__(self, name):
+            self.name = name
+            self.calls = 0
+
+        def execute_prompt(self, prompt, config):
+            self.calls += 1
+            return LLMResponse(content="match", model=self.name, usage={"prompt_tokens": 1, "completion_tokens": 1})
+
+        def validate_config(self, config):
+            return True
+
+    stubs: dict[str, _Stub] = {}
+
+    def factory(candidate, env):
+        stubs[candidate.id] = _Stub(candidate.id)
+        return stubs[candidate.id]
+
+    policy = build_routing_policy_from_config(
+        config,
+        workspace=tmp_path,
+        adapter_factory=factory,
+        shadow_baseline_id="baseline-x",
+        shadow_rate=1.0,
+    )
+
+    rule = policy.rules[0]
+    # The prefer slot is now a ShadowingAdapter wrapping candidate-a.
+    assert isinstance(rule.prefer, ShadowingAdapter)
+    assert rule.prefer.candidate_adapter is stubs["candidate-a"]
+    assert rule.prefer.baseline_adapter is stubs["baseline-x"]
+    assert rule.prefer.task_type == "extract-entities"
+    # The baseline candidate (fallback) is NOT wrapped.
+    assert rule.fallback is stubs["baseline-x"]
+
+
+def test_shadow_rate_one_fires_per_call_and_zero_skips(tmp_path: Path) -> None:
+    """ShadowingAdapter is best-effort and supplied by llm-connect.
+
+    Spot-check the wiring: at rate=1.0 the baseline.execute_prompt runs on
+    every call; at rate=0.0 it never runs.
+    """
+    from llm_connect.adapter import LLMAdapter
+    from llm_connect.models import LLMResponse, RunConfig
+    from infospace_bench.routing_config import build_routing_policy_from_config
+
+    data = {
+        "schema_version": 1,
+        "ledger_path": "quality.jsonl",
+        "task_types": {
+            "extract-entities": {
+                "candidates": [
+                    {"id": "candidate-a", "provider": "openrouter", "model": "openai/gpt-4o-mini"},
+                    {"id": "baseline-x", "provider": "claude_code", "model": "claude-opus-4-7"},
+                ],
+            },
+        },
+    }
+    config = parse_routing_config(data)
+
+    class _Counter(LLMAdapter):
+        def __init__(self, name):
+            self.name = name
+            self.calls = 0
+
+        def execute_prompt(self, prompt, config):
+            self.calls += 1
+            return LLMResponse(content="match", model=self.name, usage={"prompt_tokens": 1, "completion_tokens": 1})
+
+        def validate_config(self, config):
+            return True
+
+    def make_factory():
+        stubs: dict[str, _Counter] = {}
+
+        def factory(candidate, env):
+            stubs[candidate.id] = _Counter(candidate.id)
+            return stubs[candidate.id]
+
+        return factory, stubs
+
+    factory, stubs = make_factory()
+    policy_full = build_routing_policy_from_config(
+        config,
+        workspace=tmp_path,
+        adapter_factory=factory,
+        shadow_baseline_id="baseline-x",
+        shadow_rate=1.0,
+    )
+    # Drive the prefer adapter (synchronous shadow) and force any
+    # background shadow work to drain before we count calls.
+    shadow_adapter = policy_full.rules[0].prefer
+    shadow_adapter.async_shadow = False  # force sync grading for a deterministic count
+    for _ in range(3):
+        shadow_adapter.execute_prompt("hello", RunConfig(model_name="x"))
+    assert stubs["candidate-a"].calls == 3
+    assert stubs["baseline-x"].calls == 3, "rate=1.0 should call baseline on every call"
+
+    # Fresh factory + stubs for the zero-rate run so counters reset.
+    factory2, stubs2 = make_factory()
+    # Use a unique ledger path so the two policies do not share state.
+    (tmp_path / "subdir").mkdir(exist_ok=True)
+    data2 = {**data, "ledger_path": "subdir/quality.jsonl"}
+    config2 = parse_routing_config(data2)
+    policy_zero = build_routing_policy_from_config(
+        config2,
+        workspace=tmp_path,
+        adapter_factory=factory2,
+        shadow_baseline_id="baseline-x",
+        shadow_rate=0.0,
+    )
+    shadow_adapter2 = policy_zero.rules[0].prefer
+    shadow_adapter2.async_shadow = False
+    for _ in range(3):
+        shadow_adapter2.execute_prompt("hello", RunConfig(model_name="x"))
+    assert stubs2["candidate-a"].calls == 3
+    assert stubs2["baseline-x"].calls == 0, "rate=0.0 should skip baseline entirely"
+
+
 def test_rejects_non_string_ledger_path() -> None:
     payload = {
         "schema_version": 1,

workplans/IB-WP-0020-provider-routing-cli.md

@@ -4,7 +4,7 @@ type: workplan
 title: "Provider Routing CLI Integration"
 domain: markitect
 repo: infospace-bench
-status: active
+status: finished
 owner: markitect
 topic_slug: markitect
 created: "2026-05-18"
@@ -158,7 +158,7 @@ state_hub_task_id: "69288131-f265-4db5-a4b0-b0c8a6f55dd8"
 
 ```task
 id: IB-WP-0020-T05
-status: todo
+status: done
 priority: medium
 state_hub_task_id: "02658420-056c-4d73-8055-e6a7ab51876b"
 ```