diff --git a/docs/operations.md b/docs/operations.md
index fb0c771..d61c07a 100644
--- a/docs/operations.md
+++ b/docs/operations.md
@@ -43,7 +43,7 @@ Three built-in model profiles plus operator-defined `<custom>.yaml`. Each profil
 
 ### Custom profiles
 
-Create `lib/profiles/<custom>.yaml` to define a new tier. The validator (`lib/validators/profile-validator.mjs`) enforces: every `phase_models[].phase` must be a known phase enum; every `phase_models[].model` must match `^(opus|sonnet)(\b|-).*` or one of the canonical short names. Custom profiles override built-ins of the same name (lookup is alphabetical with `<custom>` taking precedence).
+Create `voyage-profiles/<custom>.yaml` in the repo root (or `~/.claude/voyage-profiles/<custom>.yaml`) to define a **new** tier — the name must not be a built-in. The validator (`lib/validators/profile-validator.mjs`) enforces: every `phase_models[].phase` must be a known phase enum; every `phase_models[].model` must match `^(opus|sonnet)(\b|-).*` or one of the canonical short names. `findProfilePath` (`lib/profiles/resolver.mjs`) resolves **built-in first** (`lib/profiles/<name>.yaml` for `economy`/`balanced`/`premium`), then repo-root `voyage-profiles/`, then `~/.claude/voyage-profiles/`. A custom file named after a built-in therefore **cannot** shadow it (custom profiles must use new names); for the same custom name, repo-root takes precedence over home.
 
 Drift between plan-frontmatter `profile:` and step-manifest `profile_used:` emits a `MANIFEST_PROFILE_DRIFT` warning from `plan-validator --strict` (Step 20). Plan remains valid; the warning surfaces accidental tier-mismatch.
 
diff --git a/tests/lib/doc-consistency.test.mjs b/tests/lib/doc-consistency.test.mjs
index 3951d2f..6ce5ea2 100644
--- a/tests/lib/doc-consistency.test.mjs
+++ b/tests/lib/doc-consistency.test.mjs
@@ -323,6 +323,27 @@ test('orchestrator docs do not claim ALL sub-agents run on Sonnet (agents are mo
   }
 });
 
+// --- S20 — anti-false-claim: operations.md custom-profile prose must match findProfilePath ---
+//
+// findProfilePath (lib/profiles/resolver.mjs:57) resolves built-in FIRST, then
+// repo-root voyage-profiles/, then ~/.claude/voyage-profiles/. Custom profiles
+// live in voyage-profiles/ (NOT lib/profiles/), must use NEW names, and CANNOT
+// shadow a built-in. The old prose claimed the opposite (lib/profiles/<custom>;
+// "override built-ins of the same name"; "alphabetical … precedence") — guard it.
+test('operations.md custom-profile prose matches findProfilePath resolution order [S20]', () => {
+  const ops = read('docs/operations.md');
+  for (const bad of ['lib/profiles/<custom>', 'alphabetical', 'override built-ins of the same name']) {
+    assert.ok(
+      !ops.includes(bad),
+      `docs/operations.md: false custom-profile claim "${bad}" contradicts findProfilePath — fix the prose, not this test`,
+    );
+  }
+  assert.ok(
+    ops.includes('voyage-profiles/'),
+    'docs/operations.md must point custom profiles at voyage-profiles/ (not lib/profiles/)',
+  );
+});
+
 // --- v4.1 Step 21 — pin --profile + phase_models on the 6 commands ---
 //
 // CLAUDE.md / README.md pinning is deferred to Step 22 (post-write of