diff --git a/corpus/CLAUDE.learned.md b/corpus/CLAUDE.learned.md
index a0915658..3ba236dd 100644
--- a/corpus/CLAUDE.learned.md
+++ b/corpus/CLAUDE.learned.md
@@ -45,3 +45,4 @@ Engine-only install drops this file; reflect Accepted global rules land here.
 - Before asking me whether to run a script, read its whole body, not its header comment, usage text, or `--dry-run` output, and name in the question every process it kills, file it deletes, and service it restarts. A header states what the author meant; the body is what runs, so a consent question built from the header asks me to approve something other than what will happen. No known prior art.
 - When finishing a merge or rebase, reconcile three things before calling it resolved: what each side declared (its commit messages and PR description: the intent, and the tests it names), what each side's code actually does, and what the resolved result does. All three must agree: every declared intent is still visible in `git diff <base> -- <file>`, and every test either side named still passes on the result. A merge with no textual conflict can still break one side's declared behavior, so a clean merge is checked the same way. Never take one side's whole file (`git checkout --theirs` / `--ours <file>`, or copying the file from one branch) unless the other side's changes to that file are provably empty; taking a whole side silently reverts what the other branch added, including hunks that never conflicted (git-checkout(1), `--ours`/`--theirs`: https://git-scm.com/docs/git-checkout#Documentation/git-checkout.txt---ours). When a declaration and its code disagree, or the two sides' intents contradict, stop and flag it to me instead of choosing: run `why` on the conflicting lines (`git log -L` or `git log -S` plus each commit's PR body) and apply `principle-prove-it`, so the flag names the two commits or PRs, quotes the declared intent next to the code, and pastes the failing test output. Brun, Holmes, Ernst and Notkin, "Proactive Detection of Collaboration Conflicts" (ESEC/FSE 2011, https://doi.org/10.1145/2025113.2025139), across Git, Perl5 and Voldemort, found "that 33% of merges that were reported to contain no textual conflicts by the VCS in fact contained higher-order conflicts" (build or test failures), so a clean textual merge is not evidence the two intentions still hold.
 - An item I approved as "fix it properly later" stays in every status update and every final summary, marked open, until it is done or I drop it. A recap that lists only what finished makes the deferred half disappear, and the next session never learns it was owed. No known prior art.
+- Before spending more than a couple of tool calls on an infrastructure, security, or "does X exist" question, search saved memory for the topic and for its reverse framing: the fix as well as the symptom, "X is off" as well as "X is missing". An answer already written down costs one read; rediscovering it costs the whole investigation. No known prior art.
diff --git a/engine/hooks/_sdk/runtime.py b/engine/hooks/_sdk/runtime.py
index d1ea4351..d4db3c5c 100644
--- a/engine/hooks/_sdk/runtime.py
+++ b/engine/hooks/_sdk/runtime.py
@@ -25,7 +25,7 @@ def run_hook(
         event = json.load(sys.stdin)
     except json.JSONDecodeError as exc:
         _write_findings_file([])
-        print(f"catstack-hook-error {hook}: JSONDecodeError: {exc}", file=sys.stderr)
+        print(f"catstack-hook-error {hook}: JSONDecodeError: hook payload is not JSON: {exc}", file=sys.stderr)
         stdout_text, _stderr_text, _exit_code = render(
             harness,
             hook_event_name or "",
diff --git a/engine/hooks/categorical-scope-guard/README.md b/engine/hooks/categorical-scope-guard/README.md
index 3eb5b2dc..2aabdff3 100644
--- a/engine/hooks/categorical-scope-guard/README.md
+++ b/engine/hooks/categorical-scope-guard/README.md
@@ -91,9 +91,12 @@ Do one of two things:
 
 ## Three outcomes, and the fail direction
 
-- **HIT** — exit 2 with the message above.
+- **HIT** — finding `categorical-scope-guard.partial-status-filter`. The
+  registry default is `stop`, so the shared runtime exits 2 with the
+  message above unless a local mode override lowers it to a warning.
 - **CLEAN** — exit 0.
-- **UNCHECKED** — exit 2. **This hook fails closed.** It blocks, and says
+- **UNCHECKED** — finding `categorical-scope-guard.unchecked`. **This hook
+  fails closed.** With the default `stop` mode it blocks, and says
   `UNCHECKED`, when:
   - the transcript path is absent, the file is missing, a line is malformed
     JSON (a torn final line is tolerated), the window runs past the 64 MB
@@ -132,8 +135,10 @@ reason and let the user answer.
 
 ## Files
 
-- `detect.py` — command parser, human-turn reader, `decide()`.
-- `claude_pretooluse.py` — the entrypoint.
+- `detect.py` — command parser, human-turn reader, `decide()`, and
+  `detect(event)`.
+- `claude_pretooluse.py`, `cursor_pretooluse.py`, `codex_pretooluse.py` —
+  thin runtime entrypoints.
 - `claude.hook.json`, `install_claude_hook.py` — the settings merge that
   `install.sh` runs.
 - `tests/test_hooks.py`, `tests/fixtures/` — the fixtures are real commands
diff --git a/engine/hooks/categorical-scope-guard/claude_pretooluse.py b/engine/hooks/categorical-scope-guard/claude_pretooluse.py
index 673c734c..a3724044 100644
--- a/engine/hooks/categorical-scope-guard/claude_pretooluse.py
+++ b/engine/hooks/categorical-scope-guard/claude_pretooluse.py
@@ -1,55 +1,19 @@
 #!/usr/bin/env python3
-"""Claude PreToolUse on Bash: block a status-narrowed mutation of a target the
-live human turn quantified with all / every / each. Exits 2 with the reason on
-stderr for HIT and for UNCHECKED; exits 0 for CLEAN.
-"""
+"""Claude Code PreToolUse entrypoint for categorical-scope-guard."""
 from __future__ import annotations
 
-import json
 import os
 import sys
 
-sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+sys.path.insert(0, os.path.join(
+    os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "_sdk"))
 
-from detect import CLEAN, decide_payload
-
-SHELL_LIKE_TOOL_NAMES = (
-    "Bash", "bash", "shell", "Shell", "exec", "exec_command",
-    "run_terminal_cmd", "local_shell", "run_command", "shell_call",
-)
-
-
-def _tool_name(payload: dict) -> str:
-    return str(
-        payload.get("tool_name")
-        or payload.get("toolName")
-        or payload.get("tool")
-        or payload.get("name")
-        or ""
-    )
+from detect import detect  # noqa: E402
+from runtime import run_hook  # noqa: E402
 
 
 def main() -> None:
-    raw = sys.stdin.read()
-    try:
-        payload = json.loads(raw)
-    except (json.JSONDecodeError, OSError) as exc:
-        sys.stderr.write(f"categorical-scope-guard: hook payload is not JSON, nothing to classify: {exc}\n")
-        return
-    if not isinstance(payload, dict) or _tool_name(payload) not in SHELL_LIKE_TOOL_NAMES:
-        return
-    try:
-        verdict = decide_payload(payload)
-    except Exception as exc:
-        sys.stderr.write(
-            f"categorical-scope-guard: UNCHECKED -- the detector failed ({exc!r}) while classifying a "
-            "status-filtered mutation. Blocked rather than passed; drop the status filter or rephrase the command.\n"
-        )
-        sys.exit(2)
-    if verdict.outcome == CLEAN:
-        return
-    sys.stderr.write(verdict.message + "\n")
-    sys.exit(2)
+    run_hook("categorical-scope-guard", "claude", detect, "PreToolUse")
 
 
 if __name__ == "__main__":
diff --git a/engine/hooks/categorical-scope-guard/codex_pretooluse.py b/engine/hooks/categorical-scope-guard/codex_pretooluse.py
new file mode 100644
index 00000000..e2f2a14d
--- /dev/null
+++ b/engine/hooks/categorical-scope-guard/codex_pretooluse.py
@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+"""Codex PreToolUse entrypoint for categorical-scope-guard."""
+from __future__ import annotations
+
+import os
+import sys
+
+sys.path.insert(0, os.path.join(
+    os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "_sdk"))
+
+from detect import detect  # noqa: E402
+from runtime import run_hook  # noqa: E402
+
+
+def main() -> None:
+    run_hook("categorical-scope-guard", "codex", detect, "PreToolUse")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/engine/hooks/categorical-scope-guard/cursor_pretooluse.py b/engine/hooks/categorical-scope-guard/cursor_pretooluse.py
new file mode 100644
index 00000000..bf6714e8
--- /dev/null
+++ b/engine/hooks/categorical-scope-guard/cursor_pretooluse.py
@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+"""Cursor PreToolUse entrypoint for categorical-scope-guard."""
+from __future__ import annotations
+
+import os
+import sys
+
+sys.path.insert(0, os.path.join(
+    os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "_sdk"))
+
+from detect import detect  # noqa: E402
+from runtime import run_hook  # noqa: E402
+
+
+def main() -> None:
+    run_hook("categorical-scope-guard", "cursor", detect, "PreToolUse")
+
+
+if __name__ == "__main__":
+    main()
diff --git a/engine/hooks/categorical-scope-guard/detect.py b/engine/hooks/categorical-scope-guard/detect.py
index bc0f1912..b37566b4 100644
--- a/engine/hooks/categorical-scope-guard/detect.py
+++ b/engine/hooks/categorical-scope-guard/detect.py
@@ -14,14 +14,24 @@
 from __future__ import annotations
 import sys
 
+import hashlib
 import json
 import os
 import re
 from dataclasses import dataclass, field
+from pathlib import Path
+
+SDK_DIR = Path(__file__).resolve().parents[1] / "_sdk"
+if str(SDK_DIR) not in sys.path:
+    sys.path.insert(0, str(SDK_DIR))
+
+from finding import Finding  # noqa: E402
 
 HIT = "hit"
 CLEAN = "clean"
 UNCHECKED = "unchecked"
+RULE_PARTIAL_STATUS_FILTER = "categorical-scope-guard.partial-status-filter"
+RULE_UNCHECKED = "categorical-scope-guard.unchecked"
 
 LIVE_TURNS = 4
 MAX_SCAN_BYTES = 64 * 1024 * 1024
@@ -872,3 +882,54 @@ def decide_payload(payload: dict) -> Verdict:
         return Verdict(CLEAN)
     path = payload.get("transcript_path") or payload.get("transcriptPath") or ""
     return decide(command, lambda: read_live_window(path if isinstance(path, str) else ""))
+
+
+SHELL_LIKE_TOOL_NAMES = (
+    "Bash", "bash", "shell", "Shell", "exec", "exec_command",
+    "run_terminal_cmd", "local_shell", "run_command", "shell_call",
+)
+
+
+def _tool_name(payload: dict) -> str:
+    return str(
+        payload.get("tool_name")
+        or payload.get("toolName")
+        or payload.get("tool")
+        or payload.get("name")
+        or ""
+    )
+
+
+def _command_subject(payload: dict) -> str:
+    tool_input = payload.get("tool_input") or payload.get("toolInput") or {}
+    command = tool_input.get("command") if isinstance(tool_input, dict) else ""
+    if not isinstance(command, str):
+        command = ""
+    return "command:" + hashlib.sha256(command.encode("utf-8")).hexdigest()[:16]
+
+
+def _finding(rule_id: str, payload: dict, message: str) -> Finding:
+    return Finding(
+        rule_id=rule_id,
+        subject=_command_subject(payload),
+        message=message,
+        evidence=message,
+    )
+
+
+def detect(event: dict) -> list[Finding]:
+    if _tool_name(event) not in SHELL_LIKE_TOOL_NAMES:
+        return []
+    try:
+        verdict = decide_payload(event)
+    except Exception as exc:
+        print(f"catstack-hook-error categorical-scope-guard: {type(exc).__name__}: {exc}", file=sys.stderr)
+        message = (
+            f"categorical-scope-guard: UNCHECKED -- the detector failed ({exc!r}) while classifying a "
+            "status-filtered mutation. Blocked rather than passed; drop the status filter or rephrase the command."
+        )
+        return [_finding(RULE_UNCHECKED, event, message)]
+    if verdict.outcome == CLEAN:
+        return []
+    rule_id = RULE_PARTIAL_STATUS_FILTER if verdict.outcome == HIT else RULE_UNCHECKED
+    return [_finding(rule_id, event, verdict.message)]
diff --git a/engine/hooks/categorical-scope-guard/tests/test_hooks_sdk_mode.py b/engine/hooks/categorical-scope-guard/tests/test_hooks_sdk_mode.py
new file mode 100644
index 00000000..b61c0c3b
--- /dev/null
+++ b/engine/hooks/categorical-scope-guard/tests/test_hooks_sdk_mode.py
@@ -0,0 +1,105 @@
+from __future__ import annotations
+
+import json
+import os
+import subprocess
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+HOOK_DIR = os.path.dirname(HERE)
+FIXTURES = os.path.join(HERE, "fixtures")
+ENTRYPOINT = os.path.join(HOOK_DIR, "claude_pretooluse.py")
+
+
+def fixture(name: str) -> str:
+    with open(os.path.join(FIXTURES, name), encoding="utf-8") as handle:
+        return handle.read()
+
+
+def human(text: str) -> dict[str, object]:
+    return {"type": "user", "message": {"role": "user", "content": text}}
+
+
+def write_transcript(entries: list[dict[str, object]]) -> str:
+    handle = tempfile.NamedTemporaryFile("w", suffix=".jsonl", delete=False, encoding="utf-8")
+    with handle:
+        for entry in entries:
+            handle.write(json.dumps(entry) + "\n")
+    return handle.name
+
+
+def run_entrypoint(payload: dict[str, object], env: dict[str, str]) -> subprocess.CompletedProcess[str]:
+    merged_env = os.environ.copy()
+    merged_env.update(env)
+    return subprocess.run(
+        [sys.executable, ENTRYPOINT],
+        input=json.dumps(payload),
+        capture_output=True,
+        text=True,
+        env=merged_env,
+    )
+
+
+class SdkModeTest(unittest.TestCase):
+    def test_mode_override_warn_changes_block_to_warning(self) -> None:
+        path = write_transcript([human("can you make all tasks use claude and local executor")])
+        try:
+            result = run_entrypoint(
+                {
+                    "tool_name": "Bash",
+                    "hook_event_name": "PreToolUse",
+                    "transcript_path": path,
+                    "tool_input": {"command": fixture("update_tasks_status_in_pending_queued.txt")},
+                },
+                {"CATSTACK_HOOK_MODE_CATEGORICAL_SCOPE_GUARD": "warn"},
+            )
+        finally:
+            os.unlink(path)
+
+        self.assertEqual(0, result.returncode, result.stderr)
+        self.assertEqual("", result.stderr)
+        rendered = json.loads(result.stdout)
+        self.assertIn(
+            "categorical-scope-guard",
+            rendered["hookSpecificOutput"]["additionalContext"],
+        )
+
+    def test_each_finding_writes_one_event_row_with_rule_id(self) -> None:
+        path = write_transcript([human("can you make all tasks use claude and local executor")])
+        try:
+            with tempfile.TemporaryDirectory() as tmp:
+                result = run_entrypoint(
+                    {
+                        "tool_name": "Bash",
+                        "hook_event_name": "PreToolUse",
+                        "session_id": "categorical-scope-guard-sdk-mode",
+                        "transcript_path": path,
+                        "tool_input": {"command": fixture("update_tasks_status_in_pending_queued.txt")},
+                    },
+                    {
+                        "CATSTACK_HOOK_METRICS_DIR": tmp,
+                        "CATSTACK_HOOK_MODE_CATEGORICAL_SCOPE_GUARD": "warn",
+                    },
+                )
+                rows = [
+                    json.loads(line)
+                    for file in Path(tmp).glob("events-*.jsonl")
+                    for line in file.read_text(encoding="utf-8").splitlines()
+                ]
+        finally:
+            os.unlink(path)
+
+        self.assertEqual(0, result.returncode, result.stderr)
+        self.assertEqual(1, len(rows))
+        self.assertEqual("categorical-scope-guard", rows[0]["hook"])
+        self.assertEqual("categorical-scope-guard.partial-status-filter", rows[0]["rule_id"])
+        self.assertEqual("warn", rows[0]["mode"])
+        self.assertEqual("override", rows[0]["mode_source"])
+        self.assertEqual("warned", rows[0]["action"])
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/test_check_memory_first_rule.py b/tests/test_check_memory_first_rule.py
new file mode 100644
index 00000000..15712b92
--- /dev/null
+++ b/tests/test_check_memory_first_rule.py
@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+"""Pin the learned rule: search saved memory, both ways, before a deep dive.
+
+A detector cannot judge this reliably, so the test proves the rule is present
+with its trigger, required action, and reason; deleting or hollowing it fails here.
+"""
+import os
+import unittest
+
+REPO_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+LEARNED = os.path.join(REPO_ROOT, "corpus", "CLAUDE.learned.md")
+
+
+def working_style_section():
+    with open(LEARNED, encoding="utf-8") as handle:
+        text = handle.read()
+    start = text.index("# Working style")
+    end = text.find("\n# ", start + 1)
+    return text[start:] if end == -1 else text[start:end]
+
+
+def bullet_starting(prefix):
+    for line in working_style_section().splitlines():
+        if line.startswith(prefix):
+            return line
+    raise AssertionError(f"no working-style rule starts with {prefix!r}")
+
+
+class TestCheckMemoryFirst(unittest.TestCase):
+    PREFIX = "- Before spending more than a couple of tool calls"
+
+    def test_rule_searches_memory_both_ways(self):
+        rule = bullet_starting(self.PREFIX)
+        self.assertIn("search saved memory", rule)
+        self.assertIn("reverse framing", rule)
+
+
+if __name__ == "__main__":
+    unittest.main()