diff --git a/lib/validators/profile-validator.mjs b/lib/validators/profile-validator.mjs
index 37909e8..b5fb3a0 100644
--- a/lib/validators/profile-validator.mjs
+++ b/lib/validators/profile-validator.mjs
@@ -21,7 +21,7 @@
 //   PROFILE_READ_ERROR     — file unreadable or parse-error
 //   PROFILE_NOT_FOUND      — file does not exist
 //
-// Allowed model values: ['sonnet', 'opus']. Haiku is allowed only when
+// Allowed model values: ['sonnet', 'opus', 'fable']. Haiku is allowed only when
 // VOYAGE_ALLOW_HAIKU=1 (per global CLAUDE.md modellvalg-prinsipp: Haiku skal
 // ikke brukes som default; eksplisitt opt-in for spesielle bruksmønstre).
 
@@ -42,7 +42,7 @@ export const PROFILE_REQUIRED_PHASES = Object.freeze([
   'brief', 'research', 'plan', 'execute', 'review', 'continue',
 ]);
 
-export const BASE_ALLOWED_MODELS = Object.freeze(['sonnet', 'opus']);
+export const BASE_ALLOWED_MODELS = Object.freeze(['sonnet', 'opus', 'fable']);
 
 function getAllowedModels(env = process.env) {
   if (env.VOYAGE_ALLOW_HAIKU === '1') {
diff --git a/tests/validators/profile-validator.test.mjs b/tests/validators/profile-validator.test.mjs
index 37c3806..7cd3fec 100644
--- a/tests/validators/profile-validator.test.mjs
+++ b/tests/validators/profile-validator.test.mjs
@@ -12,6 +12,7 @@ import {
   validateProfileContent,
   PROFILE_REQUIRED_FIELDS,
   PROFILE_REQUIRED_PHASES,
+  BASE_ALLOWED_MODELS,
 } from '../../lib/validators/profile-validator.mjs';
 
 const __dirname = dirname(fileURLToPath(import.meta.url));
@@ -93,6 +94,77 @@ brief_reviewer_iter_cap: 1
     `expected valid with VOYAGE_ALLOW_HAIKU=1, got: ${JSON.stringify(allowed.errors)}`);
 });
 
+// Fable tier (v5.9): fable accepted under DEFAULT env (no opt-in flag),
+// unknown models still rejected — the allowlist gate must demonstrably fire.
+
+test('fable accepted in phase_models under default env (no env flag)', () => {
+  const fableProfile = `---
+profile_version: "1.0"
+name: fable-inline
+phase_models:
+  - phase: brief
+    model: fable
+  - phase: research
+    model: fable
+  - phase: plan
+    model: fable
+  - phase: execute
+    model: fable
+  - phase: review
+    model: fable
+  - phase: continue
+    model: fable
+parallel_agents_min: 6
+parallel_agents_max: 8
+external_research_enabled: true
+brief_reviewer_iter_cap: 3
+---
+`;
+  const r = validateProfileContent(fableProfile, { env: { /* default: no flags */ } });
+  assert.equal(r.valid, true,
+    `expected fable accepted under default env, got: ${JSON.stringify(r.errors)}`);
+  assert.equal(r.errors.length, 0);
+});
+
+test('unknown model gpt5 rejected with PROFILE_INVALID_MODEL under default env', () => {
+  const gpt5Profile = `---
+profile_version: "1.0"
+name: gpt5-inline
+phase_models:
+  - phase: brief
+    model: gpt5
+  - phase: research
+    model: sonnet
+  - phase: plan
+    model: opus
+  - phase: execute
+    model: sonnet
+  - phase: review
+    model: opus
+  - phase: continue
+    model: sonnet
+parallel_agents_min: 2
+parallel_agents_max: 4
+external_research_enabled: false
+brief_reviewer_iter_cap: 1
+---
+`;
+  const r = validateProfileContent(gpt5Profile, { env: { /* default: no flags */ } });
+  assert.equal(r.valid, false);
+  const found = r.errors.find(e => e.code === 'PROFILE_INVALID_MODEL' && /gpt5/.test(e.message));
+  assert.ok(found, `expected PROFILE_INVALID_MODEL for gpt5, got: ${JSON.stringify(r.errors)}`);
+});
+
+// BASE_ALLOWED_MODELS allowlist drift-pin (mirrors the PROFILE_REQUIRED_FIELDS pin)
+
+test('BASE_ALLOWED_MODELS export drift-pin', () => {
+  assert.deepEqual(
+    [...BASE_ALLOWED_MODELS],
+    ['sonnet', 'opus', 'fable'],
+    'BASE_ALLOWED_MODELS contract drift — pin contract',
+  );
+});
+
 // Required fields presence
 
 test('PROFILE_MISSING_FIELD when name absent', () => {