diff --git a/CLAUDE.md b/CLAUDE.md
index 5c31c9d2..18fbf777 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -125,7 +125,8 @@ controls (`ui/Input`, `Checkbox`, `Slider`, …), glass surfaces (`SURFACE.*`),
   "no results". Reads degrade honestly; writes are conditional (`UPDATE … WHERE status='running'`).
 - **i18n parity.** HU/EN, zero key drift. Every user-facing string is translated.
 - **Comment the "why", keep it current.** This codebase uses comments as its architecture doc; a stale
-  "why" is a liability, so update it when the behavior changes.
+  "why" is a liability, so update it when the behavior changes. Say the why itself, never the plan
+  step that produced it: no epic, sprint or review-round ids in the code (`planCodes.contract.test.ts`).
 
 ---
 
diff --git a/frontend/src/lib/planCodes.contract.test.ts b/frontend/src/lib/planCodes.contract.test.ts
new file mode 100644
index 00000000..5547c7cb
--- /dev/null
+++ b/frontend/src/lib/planCodes.contract.test.ts
@@ -0,0 +1,59 @@
+import { execFileSync } from "node:child_process";
+import { existsSync, readFileSync } from "node:fs";
+import { describe, expect, it } from "vitest";
+
+// The code says WHY; the plan that produced it stays in the private ops repo. A comment that cites
+// `E28 review J4`, `(R6 S3b)` or `deep-review round 5` names a document no reader of this repo has,
+// so the citation is noise at best, and at worst a rule that only makes sense next to the plan. All
+// of them were taken out at once (2026-10-04); this keeps new ones out of every tracked text file and
+// every new one not yet added (comments, docstrings, test titles, lint messages alike).
+//
+// Not scanned: Markdown (the docs and the changelog keep a decision's date and its epic as history)
+// and the Alembic migrations (each one is a dated record of what changed).
+
+const REPO = new URL("../../../", import.meta.url);
+const SKIPPED =
+  /\.(md|webp|png|jpe?g|ico|woff2?)$|^backend\/alembic\/versions\/|package-lock\.json$/;
+// the guard itself, and the metric that counts epics by the same definition
+const ALLOWED = new Set([
+  "frontend/src/lib/planCodes.contract.test.ts",
+  "scripts/audit_metrics.py",
+]);
+const PLAN_CODES = [
+  // an epic (`E28`, `E9.5`) or an older roadmap item (`R14`) — not `E2E`, not a ruff rule family
+  // (`E4/E7/E9`), not a TV episode (`S2 · E5`, a test show's episode titled "E1")
+  /(?<!S\d{1,2}\s?·?\s?)(?<![/"])\b(?:E\d{1,2}(?:\.\d+)?|R\d{1,2})\b(?![/"E])/,
+  // a sprint cited on its own (`(S6)`, `S3e2`) or a review round (`round 4`, `deep-review`) — not
+  // `S3h`, the media-card decision docs/DESIGN.md is headed by and the design lab labels
+  /\(S\d{1,2}[a-z]?\d?\)|\bS(?!3h\b)\d{1,2}[a-z]\d?\b|\b[Rr]ound[ -]\d|deep-review/,
+];
+
+function tracked(): string[] {
+  const out = execFileSync(
+    "git",
+    ["ls-files", "-z", "--cached", "--others", "--exclude-standard"],
+    {
+      cwd: REPO,
+      encoding: "utf-8",
+    },
+  );
+  // a file deleted but not yet staged is still listed
+  return out
+    .split("\0")
+    .filter((f) => f && !SKIPPED.test(f) && !ALLOWED.has(f) && existsSync(new URL(f, REPO)));
+}
+
+describe("plan codes", () => {
+  it("are not cited in the code", () => {
+    const files = tracked();
+    expect(files.length).toBeGreaterThan(1000); // a scan that reads nothing is green over nothing
+    const hits = files.flatMap((f) =>
+      readFileSync(new URL(f, REPO), "utf-8")
+        .split("\n")
+        .flatMap((line, i) =>
+          PLAN_CODES.some((re) => re.test(line)) ? [`${f}:${i + 1}: ${line.trim()}`] : [],
+        ),
+    );
+    expect(hits).toEqual([]);
+  });
+});
diff --git a/scripts/audit_metrics.py b/scripts/audit_metrics.py
index 5a55670a..93b12e0c 100644
--- a/scripts/audit_metrics.py
+++ b/scripts/audit_metrics.py
@@ -25,9 +25,12 @@ BE_TESTS = ROOT / "backend" / "tests"
 FE_SRC = ROOT / "frontend" / "src"
 BIG_FILE = 800
 BE_COMPLEXITY = 10  # ruff's C901 default
-FE_COMPLEXITY = 20  # the frontend's line (E32)
+FE_COMPLEXITY = 20  # the frontend's line
 
-EPIC_CODE = re.compile(r"\b(E\d{2}|R\d{1,2})(\s?S\d+)?\b")
+# what planCodes.contract.test.ts holds the code to: an epic (`E28`, `E9.5`) or a roadmap item (`R14`),
+# not `E2E`, not a ruff rule family (`E4/E7/E9`), not a TV episode (`S2 · E5`, an episode titled "E1")
+EPIC_CODE = re.compile(r'(?<![/"])\b(E\d{1,2}(\.\d+)?|R\d{1,2})\b(?![/"E])')
+EPISODE = re.compile(r"S\d{1,2}\s?·?\s?E\d+")
 NARRATION = re.compile(r"\b(used to|no longer)\b", re.IGNORECASE)
 
 
@@ -111,7 +114,7 @@ def _complexity() -> dict[str, object]:
 
 def _noise(be: list[tuple[Path, list[str]]], fe: list[tuple[Path, list[str]]]) -> dict[str, object]:
     every = be + fe
-    epic = [(p, ln) for p, ls in every for ln in ls if EPIC_CODE.search(ln)]
+    epic = [(p, ln) for p, ls in every for ln in ls if EPIC_CODE.search(EPISODE.sub("", ln))]
     be_c = sum(_comment_lines(ls, True) for _, ls in be)
     fe_c = sum(_comment_lines(ls, False) for _, ls in fe)
     return {