diff --git a/.claude-plugin/plugin.json b/.claude-plugin/plugin.json
index c509b6e..f788820 100644
--- a/.claude-plugin/plugin.json
+++ b/.claude-plugin/plugin.json
@@ -1,6 +1,6 @@
 {
   "name": "pm",
-  "version": "0.24.0",
+  "version": "0.25.0",
   "description": "A lightweight project-management layer that sits above OpenSpec and Superpowers. Tracks active proposals as epics, maintains an explicit detour stack, and enforces a reconcile gate so nothing is lost when development pivots or context is compacted.",
   "author": {
     "name": "Rob Sherman",
diff --git a/.conductor/render-stamp.json b/.conductor/render-stamp.json
index 8d438f8..14a0098 100644
--- a/.conductor/render-stamp.json
+++ b/.conductor/render-stamp.json
@@ -1,4 +1,4 @@
 {
-  "renderedAt": "2026-07-30T15:40:51.660Z",
-  "stateMtimeMs": 1785426051639.6658
+  "renderedAt": "2026-07-30T21:21:55.794Z",
+  "stateMtimeMs": 1785446515777.2825
 }
diff --git a/.conductor/state.json b/.conductor/state.json
index c151ad0..bb795c8 100644
--- a/.conductor/state.json
+++ b/.conductor/state.json
@@ -1219,7 +1219,7 @@
       "id": "edd-observe-hardcodes-claude-md",
       "title": "observe.py hardcodes CLAUDE.md -- a second, undeclared platform seam",
       "priority": "P1",
-      "status": "queued",
+      "status": "archived",
       "role": "epic",
       "lane": "claude-code",
       "links": [
@@ -1234,9 +1234,10 @@
       "stories": [
         {
           "title": "fold into the rules-block epic: once the engine writes a per-platform rules-block target, update observe() to match and prove both with one eval",
-          "done": false
+          "done": true
         }
-      ]
+      ],
+      "completedAt": "2026-07-30T21:21:55.677Z"
     },
     {
       "id": "edd-user-memory-confound-control-run",
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 60ded66..f5a8173 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,23 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 ## [Unreleased]
 
+## [0.25.0] — 2026-07-30
+
+### Added
+
+- **`rules-target` — a read-only query printing the absolute path of the file the resolved
+  platform's rules block belongs in**, walking that platform's first-match-wins chain. It
+  deliberately does **not** record a platform: a query must not mutate state the way
+  `write-rules` does.
+
+  It exists so tooling around pm never has to mirror `PLATFORM_RULES_CHAIN`. `evals/observe.py`
+  hardcoded `CLAUDE.md`, which 0.24.0 quietly turned into a *second* platform seam — once the
+  engine began writing a per-platform target, the observer reported `rules_block_present: false`
+  for any platform whose block lands elsewhere. That is a confident wrong answer, and it would
+  have surfaced on the first Hermes or Codex run as a parity failure that is not real. Copying
+  the chain into Python was rejected: a second copy of platform knowledge only *moves* the
+  drift instead of removing it.
+
 ## [0.24.0] — 2026-07-30
 
 ### Added
diff --git a/PROJECT.md b/PROJECT.md
index e57ef82..613594c 100644
--- a/PROJECT.md
+++ b/PROJECT.md
@@ -3,7 +3,7 @@
 > GENERATED by the `pm` plugin — do not hand-edit. Source of truth is
 > `.conductor/state.json` (ordering, detours, links) + OpenSpec `tasks.md` (stories).
 > Regenerate: `/pm:status` (or `node scripts/conductor.mjs render`).
-> Last rendered: 2026-07-30T15:40:51.653Z
+> Last rendered: 2026-07-30T21:21:55.691Z
 
 ## Now
 
@@ -23,7 +23,7 @@ _Empty — no work is paused._
 | P1 | `df-hierarchy-executor-must-check-readme-for-user-facing-changes` | claude-code | epic | archived | — | - |
 | P1 | `df-live-infra-epic-session-continuity-warning` | claude-code | epic | archived 🤖 | — | - |
 | P1 | `df-readme-stale-since-gate-guard` | claude-code | epic | archived | — | - |
-| P1 | `edd-observe-hardcodes-claude-md` | claude-code | epic | queued | 0/1 stories | depends-on→rules-block-hardcodes-claude-slash-commands |
+| P1 | `edd-observe-hardcodes-claude-md` | claude-code | epic | archived | 1/1 stories | depends-on→rules-block-hardcodes-claude-slash-commands |
 | P1 | `edd-user-memory-confound-control-run` | claude-code | epic | queued | 0/5 stories | blocks→hermes-platform-support |
 | P1 | `gh-65-autodetour-false-positives` | claude-code | epic | queued | 2/4 stories | - |
 | P1 | `pm-fix-link-flag-validation-and-update` | claude-code | epic | archived | — | - |
@@ -113,12 +113,12 @@ CONDUCTOR STATE — where we are and what's next
 NOW: (no active epic set)
 
 NEXT UP (by priority, then lane):
-  • `edd-observe-hardcodes-claude-md` (P1, claude-code, queued) — 0/1 stories
   • `edd-user-memory-confound-control-run` (P1, claude-code, queued) — 0/5 stories
   • `gh-65-autodetour-false-positives` (P1, claude-code, queued) — 2/4 stories
   • `autodetour-parser-misses-am-and-f` (P2, claude-code, queued) — 0/3 stories
   • `edd-adapter-discards-agent-stdout` (P2, claude-code, queued) — —
-  (+7 more — see PROJECT.md)
+  • `edd-measures-installed-plugin-not-worktree` (P2, claude-code, queued) — —
+  (+6 more — see PROJECT.md)
   lanes: openspec 2 · superpowers 5 · claude-code 55 · decision 7
 
 planned: 2 — see PROJECT.md
@@ -141,7 +141,7 @@ EPIC LINKS:
   • `portfolio-architecture-consistency-scan` depends-on `epic-hierarchy-orchestration` — C presumes B's hierarchy execution exists to propagate cross-cutting decisions into
 
 TRACKER SYNC (github-issues):
-  ⚠ not yet in github-issues — create issues + record keys (update-epic): `edd-observe-hardcodes-claude-md`, `edd-user-memory-confound-control-run`, `autodetour-parser-misses-am-and-f`, `edd-adapter-discards-agent-stdout`, `edd-measures-installed-plugin-not-worktree`, `platform-switch-orphans-old-rules-block`, `multi-platform-agent-support`
+  ⚠ not yet in github-issues — create issues + record keys (update-epic): `edd-user-memory-confound-control-run`, `autodetour-parser-misses-am-and-f`, `edd-adapter-discards-agent-stdout`, `edd-measures-installed-plugin-not-worktree`, `platform-switch-orphans-old-rules-block`, `multi-platform-agent-support`
 
 💡 1 tracker configured (github-issues) — consider `/pm:sync` this session to pull in any new issues.
 
diff --git a/README.md b/README.md
index 6607b88..9efb709 100644
--- a/README.md
+++ b/README.md
@@ -46,10 +46,10 @@ Not a benchmark — real numbers pulled straight from this repo's own history, v
 - Every multi-agent hierarchy dispatch runs **worktree-isolated**, unattended, converging back
   through sequential merge with **zero data loss** — every conflict seen so far has been
   mechanical (a shared CHANGELOG header, a usage string), never a real logic collision.
-- **38 releases** shipped end-to-end (spec → build → test → changelog → version bump → release)
+- **39 releases** shipped end-to-end (spec → build → test → changelog → version bump → release)
   with the plugin managing its own backlog the entire time.
-- **282 tests**, **0 dependencies** — the entire engine is Node 18+ built-ins only, ~2,900 lines
-  across a 130-line `scripts/conductor.mjs` entry point and 26 `scripts/lib/*.mjs` modules,
+- **287 tests**, **0 dependencies** — the entire engine is Node 18+ built-ins only, ~2,900 lines
+  across a 140-line `scripts/conductor.mjs` entry point and 26 `scripts/lib/*.mjs` modules,
   nothing to `npm install`. The suite itself is split across 11 files so it runs in parallel.
 - Caught its own bugs mid-flight, live: a stale-cache silent fallback, an archived-child leak in
   hierarchy planning, a false-positive auto-detour heuristic — each found by using the tool on
@@ -488,6 +488,11 @@ pre-0.24.0 state file that predates the field — re-renders `PROJECT.md`, and s
 `pmVersion`. Idempotent — safe to run more than once. Requires `/reload-plugins` first if you
 just updated the plugin (the SessionStart briefing tells you when).
 
+The engine also exposes `rules-target`, a read-only query printing the absolute path of the file
+the recorded platform's rules block belongs in (resolving that platform's first-match-wins
+chain). It exists so tooling around pm never has to mirror the chain — a second copy of platform
+knowledge is drift waiting to happen. Unlike `write-rules`, it records nothing.
+
 After showing the changelog delta ("What's new in pm"), the agent reviews each `Added`
 headline and recommends adopting any opt-in capability that's relevant to this repo's current
 `.conductor/state.json` (e.g. secondary trackers, `thorough` review mode) — one line, one
diff --git a/evals/adapter.py b/evals/adapter.py
index 39164e9..04517c6 100644
--- a/evals/adapter.py
+++ b/evals/adapter.py
@@ -43,6 +43,7 @@ def _failure(error: str) -> dict:
         "epic_ids": [],
         "detours": [],
         "rules_block_present": False,
+        "rules_block_file": None,
         "project_md_present": False,
         "new_epics": [],
         "exit_code": INFRA_FAILURE_EXIT_CODE,
diff --git a/evals/observe.py b/evals/observe.py
index 5c2e9a4..b362840 100644
--- a/evals/observe.py
+++ b/evals/observe.py
@@ -8,8 +8,15 @@
 from __future__ import annotations
 
 import json
+import os
+import subprocess
 from pathlib import Path
 
+ENGINE = Path(__file__).resolve().parent.parent / "scripts" / "conductor.mjs"
+
+# Only the stable PREFIX, never the full decorated marker. The engine's own detection keys on
+# this same prefix precisely so the parenthetical can change without stranding older blocks --
+# matching the full string here would re-create that bug on the observer side.
 RULES_BEGIN = "<!-- BEGIN pm-conductor rules"
 
 
@@ -27,6 +34,37 @@ def _read_detours(path: Path) -> list[dict]:
     return rows
 
 
+def _rules_target(project: Path) -> Path | None:
+    """Ask the ENGINE which file this project's rules block belongs in.
+
+    Deliberately a subprocess call rather than mirroring PLATFORM_RULES_CHAIN in Python. This
+    module used to hardcode `CLAUDE.md`, which quietly made it a SECOND platform seam: once the
+    engine started writing a per-platform target, the observer reported rules_block_present=False
+    for any platform whose block lands elsewhere -- a confident wrong answer that would surface
+    as a fake parity failure on the first non-Claude run. A Python copy of the chain would only
+    move that drift rather than remove it, so the engine stays the single source of truth.
+
+    Returns None when the engine cannot answer (not installed, not a pm project, a timeout).
+    None is "cannot tell", which the caller renders as absent rather than raising -- an eval
+    must be able to score a broken run, not crash on it.
+    """
+    try:
+        proc = subprocess.run(
+            ["node", str(ENGINE), "rules-target"],
+            cwd=project,
+            env={**os.environ, "CLAUDE_PROJECT_DIR": str(project), "PM_QUIET_ENGINE_BANNER": "1"},
+            capture_output=True,
+            text=True,
+            timeout=60,
+        )
+    except (OSError, subprocess.SubprocessError):
+        return None
+    if proc.returncode != 0:
+        return None
+    out = proc.stdout.strip()          # stdout ONLY -- stderr may still carry engine chatter
+    return Path(out) if out else None
+
+
 def observe(project: Path) -> dict:
     project = Path(project)
     state_path = project / ".conductor" / "state.json"
@@ -43,13 +81,20 @@ def observe(project: Path) -> dict:
         for e in state.get("epics", [])
     ]
 
-    claude_md = project / "CLAUDE.md"
+    # Where the block BELONGS for this project's recorded platform -- not a guess, and not
+    # "wherever a block happens to exist". Reporting the filename alongside the boolean makes a
+    # failure diagnosable without a re-run: "false" and "false, and we were looking at AGENTS.md"
+    # are very different findings.
+    target = _rules_target(project)
 
     return {
         "active": state.get("active"),
         "epics": epics,
         "epic_ids": [e["id"] for e in epics],
         "detours": _read_detours(project / ".conductor" / "detours.log"),
-        "rules_block_present": claude_md.exists() and RULES_BEGIN in claude_md.read_text(),
+        "rules_block_present": bool(
+            target and target.exists() and RULES_BEGIN in target.read_text()
+        ),
+        "rules_block_file": target.name if target else None,
         "project_md_present": (project / "PROJECT.md").exists(),
     }
diff --git a/evals/tests/test_observe.py b/evals/tests/test_observe.py
index 74e04d6..588533a 100644
--- a/evals/tests/test_observe.py
+++ b/evals/tests/test_observe.py
@@ -21,3 +21,52 @@ def test_observe_is_json_serializable(tmp_path: Path):
 
     project = materialize("single-active-epic", tmp_path)
     json.dumps(observe(project))  # must not raise
+
+
+def test_observe_finds_the_block_where_a_NON_claude_platform_writes_it(tmp_path: Path):
+    """The regression this epic exists for.
+
+    observe() used to hardcode CLAUDE.md. Once the engine started writing a per-platform target,
+    that made observe a SECOND, undeclared platform seam: a codex project's block lands in
+    AGENTS.md, so the observer reported rules_block_present=False -- a confident wrong answer
+    that would surface on the first non-Claude run as a parity failure that is not real.
+
+    This test fails under the old behavior and passes now.
+    """
+    import subprocess
+    import os
+
+    project = materialize("single-active-epic", tmp_path)
+    engine = Path(__file__).resolve().parent.parent.parent / "scripts" / "conductor.mjs"
+
+    # Re-target this project at codex, exactly as a codex host would declare itself.
+    subprocess.run(
+        ["node", str(engine), "write-rules", "--platform", "codex"],
+        cwd=project,
+        env={**os.environ, "CLAUDE_PROJECT_DIR": str(project), "PM_QUIET_ENGINE_BANNER": "1"},
+        capture_output=True, text=True, check=True, timeout=60,
+    )
+
+    assert (project / "AGENTS.md").exists(), "codex's block belongs in AGENTS.md"
+
+    out = observe(project)
+
+    assert out["rules_block_file"] == "AGENTS.md", (
+        "observe must follow the platform's target, not assume CLAUDE.md"
+    )
+    assert out["rules_block_present"] is True, (
+        "the block IS present -- reporting False here is the exact bug this epic fixed"
+    )
+
+
+def test_observe_reports_cannot_tell_rather_than_crashing_outside_a_pm_project(tmp_path: Path):
+    """A broken run must be SCOREABLE, not an exception -- same principle as the adapter's
+    infrastructural-failure guard. An eval that raises cannot report a verdict."""
+    bare = tmp_path / "not-a-pm-project"
+    bare.mkdir()
+
+    out = observe(bare)
+
+    assert out["rules_block_present"] is False
+    assert out["project_md_present"] is False
+    assert out["epic_ids"] == []
diff --git a/scripts/conductor.mjs b/scripts/conductor.mjs
index 4415bd9..c3d8339 100644
--- a/scripts/conductor.mjs
+++ b/scripts/conductor.mjs
@@ -45,8 +45,9 @@ import { pluginVersion } from "./lib/plugin-meta.mjs";
 import {
   currentTracker, currentSecondaryTrackers, currentReviewMode, rulesBlock, writeRules,
 } from "./lib/rules.mjs";
-import { resolvePlatform, assertKnownPlatform, platformFlag, resolveAndRecordPlatform } from "./lib/platform.mjs";
+import { resolvePlatform, assertKnownPlatform, platformFlag, resolveAndRecordPlatform, rulesTarget } from "./lib/platform.mjs";
 import { loadState } from "./lib/state.mjs";
+import { ROOT } from "./lib/constants.mjs";
 import { setActive, clearActive } from "./lib/active-pointer.mjs";
 import { setAutonomy } from "./lib/autonomy.mjs";
 import { parseFlags, planHierarchy, addEpic } from "./lib/add-epic.mjs";
@@ -124,7 +125,16 @@ if (showEngineBanner) {
     writeRules(platform);
     if (switched) process.stderr.write(`conductor: platform: ${platform}\n`);
   },
+  // Read-only query: which file does this platform's rules block belong in? Exists so a
+  // CONSUMER (evals/observe.py) never has to mirror PLATFORM_RULES_CHAIN -- a second copy of
+  // platform knowledge is exactly the drift this epic was filed to remove. Deliberately does
+  // NOT record the platform: a query must not mutate state the way write-rules does.
+  "rules-target": () => {
+    const declared = platformFlag(process.argv.slice(3));
+    if (declared) assertKnownPlatform(declared);
+    process.stdout.write(rulesTarget(resolvePlatform({ platform: declared }, loadState()), ROOT) + "\n");
+  },
 }[cmd] || (() => {
-  process.stderr.write("usage: conductor.mjs init|render|brief|snapshot|commit-nudge|sync|log-detour|honcho-memory|add-epic|add-many|update-epic|remove-epic|set-active|clear-active|set-tracker|set-lane-routing|suggest-lane|set-autonomy|record-reconcile|record-gate-review|set-review-mode|set-gate-guard|gate-guard|plan-hierarchy|verify-worktrees|verify-state|changesets|upgrade|changelog|rules|write-rules\n");
+  process.stderr.write("usage: conductor.mjs init|render|brief|snapshot|commit-nudge|sync|log-detour|honcho-memory|add-epic|add-many|update-epic|remove-epic|set-active|clear-active|set-tracker|set-lane-routing|suggest-lane|set-autonomy|record-reconcile|record-gate-review|set-review-mode|set-gate-guard|gate-guard|plan-hierarchy|verify-worktrees|verify-state|changesets|upgrade|changelog|rules|write-rules|rules-target\n");
   process.exit(1);
 }))();
diff --git a/scripts/test/platform.test.mjs b/scripts/test/platform.test.mjs
index b26bb5d..f2bfaa2 100644
--- a/scripts/test/platform.test.mjs
+++ b/scripts/test/platform.test.mjs
@@ -244,3 +244,56 @@ test("every pm-authored Claude Code hook command declares its platform", () => {
     assert.match(c, /--platform claude-code/, `hook command does not declare its platform: ${c}`);
   }
 });
+
+// ── rules-target: expose the resolved target so consumers stop guessing it ──
+// evals/observe.py hardcoded CLAUDE.md, which made it a SECOND platform seam: the engine now
+// writes a per-platform target, so the observer reported rules_block_present=false for any
+// platform whose block lands elsewhere -- a confident wrong answer that would surface as a fake
+// parity failure on the first non-Claude run. Rather than mirror PLATFORM_RULES_CHAIN into
+// Python (a second copy that can drift, which is the same class of bug), the engine answers.
+
+test("rules-target prints the absolute path for the default platform", () => {
+  const cwd = tmpRepo();
+  run(["init"], { cwd });
+  const out = run(["rules-target"], { cwd, env: { CLAUDECODE: "" } }).trim();
+  assert.equal(out, path.join(cwd, "CLAUDE.md"));
+  assert.ok(path.isAbsolute(out), "must be absolute so a consumer can use it directly");
+});
+
+test("rules-target honours --platform and the per-platform chain", () => {
+  const cwd = tmpRepo();
+  run(["init"], { cwd });
+  assert.equal(run(["rules-target", "--platform", "codex"], { cwd }).trim(),
+    path.join(cwd, "AGENTS.md"), "codex reads AGENTS.md and never CLAUDE.md");
+  // Clean repo: hermes gets the chain's LAST entry (most broadly compatible), not HERMES.md.
+  assert.equal(run(["rules-target", "--platform", "hermes"], { cwd }).trim(),
+    path.join(cwd, "CLAUDE.md"));
+});
+
+test("rules-target resolves first-existing-wins, so it tracks what the platform will READ", () => {
+  const cwd = tmpRepo();
+  run(["init"], { cwd });
+  fs.writeFileSync(path.join(cwd, "AGENTS.md"), "# left by a prior agent\n");
+  assert.equal(run(["rules-target", "--platform", "hermes"], { cwd }).trim(),
+    path.join(cwd, "AGENTS.md"),
+    "AGENTS.md outranks CLAUDE.md in hermes' chain, so that is what it will read");
+});
+
+test("rules-target is READ-ONLY -- it must not record a platform or create state", () => {
+  const cwd = tmpRepo();
+  run(["init"], { cwd });
+  const before = fs.readFileSync(path.join(cwd, ".conductor", "state.json"), "utf8");
+  run(["rules-target", "--platform", "codex"], { cwd });
+  assert.equal(fs.readFileSync(path.join(cwd, ".conductor", "state.json"), "utf8"), before,
+    "a query must not persist a platform switch -- only init/write-rules do that");
+});
+
+test("rules-target rejects an unknown --platform rather than defaulting", () => {
+  const cwd = tmpRepo();
+  run(["init"], { cwd });
+  const r = spawnSync("node", [ENGINE, "rules-target", "--platform", "nope"], {
+    cwd, env: { ...process.env, CLAUDE_PROJECT_DIR: cwd, PM_CACHE_ROOT: EMPTY_CACHE }, encoding: "utf8",
+  });
+  assert.equal(r.status, 1);
+  assert.match(r.stderr, /--platform must be one of claude-code\|hermes\|codex/);
+});
diff --git a/skills/conductor/SKILL.md b/skills/conductor/SKILL.md
index 492d92f..307f75b 100644
--- a/skills/conductor/SKILL.md
+++ b/skills/conductor/SKILL.md
@@ -57,6 +57,10 @@ Below, `$ENGINE` means the path resolved this way.
 right before the context window collapses, so nothing is lost to compaction) ·
 `write-rules` (invoked by `/pm:init`/`/pm:upgrade` — refreshes the managed rules block in
 CLAUDE.md, or the recorded `--platform`'s equivalent file; not meant to be run standalone) ·
+`rules-target` (read-only query — prints the absolute path of the file the recorded platform's
+rules block belongs in, resolving that platform's first-match-wins chain. Exists so a consumer
+never has to mirror the chain: a second copy of platform knowledge is drift waiting to happen.
+Does not record a platform, unlike `write-rules`) ·
 `/pm:resume` resume + reconcile (writes the reconciler's verdict back durably via
 `record-reconcile`) · `record-gate-review <id> --gate 1|2 --verdict pass|fail` records an
 openspec-lane epic's Gate 1/Gate 2 review verdict (see "OpenSpec build" below); `update-epic