diff --git a/.changeset/wise-mice-cheer.md b/.changeset/wise-mice-cheer.md
new file mode 100644
index 000000000..037635d73
--- /dev/null
+++ b/.changeset/wise-mice-cheer.md
@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 3188
+---
+config-set resolve_model_ids no longer rejected with "Unknown config key"; workflow._auto_chain_active written by workflows no longer emits spurious key-validation errors. Fixes #3162.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6754c6610..9766aa24a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -309,6 +309,15 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
   pre-existing sentinel force-removes the orphan worktree before starting fresh, making
   the agent self-healing across crashes. (#2839)
 
+- **`config-set resolve_model_ids` no longer rejected** — `resolve_model_ids` was
+  documented in CONFIGURATION.md and read by model-resolution paths, but missing from
+  the CJS/SDK `VALID_CONFIG_KEYS` allowlists. Added to both. (#3162)
+- **`config-set workflow._auto_chain_active` no longer emits spurious errors** — this
+  internal runtime-state key is written by `plan-phase`, `execute-phase`,
+  `discuss-phase`, `transition`, and `new-project` workflows via `config-set`, but was
+  excluded from the public allowlist after #2530. A new `RUNTIME_STATE_KEYS` set lets
+  `isValidConfigKey()` accept it without exposing it as a user-settable option. (#3162)
+
 
 ## [1.39.1] - 2026-05-01
 
diff --git a/get-shit-done/bin/lib/config-schema.cjs b/get-shit-done/bin/lib/config-schema.cjs
index 2fec078c0..bba9d44b0 100644
--- a/get-shit-done/bin/lib/config-schema.cjs
+++ b/get-shit-done/bin/lib/config-schema.cjs
@@ -69,6 +69,18 @@ const VALID_CONFIG_KEYS = new Set([
   'claude_md_assembly.mode',
   // #2517 — runtime-aware model profiles
   'runtime',
+  // #3162 — documented top-level key: controls model ID resolution for non-Claude runtimes
+  'resolve_model_ids',
+]);
+
+/**
+ * Internal runtime-state keys — accepted by config-set (workflows write them) but not
+ * exposed as user-settable options.  Excluded from VALID_CONFIG_KEYS so they stay out of
+ * the public docs-parity check and the "Valid keys:" error message.
+ * See: #3162 (workflow._auto_chain_active written by plan/execute/discuss workflows)
+ */
+const RUNTIME_STATE_KEYS = new Set([
+  'workflow._auto_chain_active',
 ]);
 
 /**
@@ -98,11 +110,12 @@ const DYNAMIC_KEY_PATTERNS = [
 ];
 
 /**
- * Returns true if keyPath is a valid config key (exact or dynamic pattern).
+ * Returns true if keyPath is a valid config key (exact, dynamic pattern, or runtime state).
  */
 function isValidConfigKey(keyPath) {
   if (VALID_CONFIG_KEYS.has(keyPath)) return true;
+  if (RUNTIME_STATE_KEYS.has(keyPath)) return true;
   return DYNAMIC_KEY_PATTERNS.some((p) => p.test(keyPath));
 }
 
-module.exports = { VALID_CONFIG_KEYS, DYNAMIC_KEY_PATTERNS, isValidConfigKey };
+module.exports = { VALID_CONFIG_KEYS, RUNTIME_STATE_KEYS, DYNAMIC_KEY_PATTERNS, isValidConfigKey };
diff --git a/sdk/src/query/config-mutation.ts b/sdk/src/query/config-mutation.ts
index 4ac28f7df..5ed243ed0 100644
--- a/sdk/src/query/config-mutation.ts
+++ b/sdk/src/query/config-mutation.ts
@@ -23,7 +23,7 @@ import { homedir } from 'node:os';
 import { join } from 'node:path';
 import { GSDError, ErrorClassification } from '../errors.js';
 import { VALID_PROFILES, getAgentToModelMapForProfile } from './config-query.js';
-import { VALID_CONFIG_KEYS, DYNAMIC_KEY_PATTERNS } from './config-schema.js';
+import { VALID_CONFIG_KEYS, RUNTIME_STATE_KEYS, DYNAMIC_KEY_PATTERNS } from './config-schema.js';
 import { planningPaths } from './helpers.js';
 import { acquireStateLock, releaseStateLock } from './state-mutation.js';
 import { maskIfSecret } from './secrets.js';
@@ -86,6 +86,7 @@ const CONFIG_KEY_SUGGESTIONS: Record<string, string> = {
  */
 export function isValidConfigKey(keyPath: string): { valid: boolean; suggestion?: string } {
   if (VALID_CONFIG_KEYS.has(keyPath)) return { valid: true };
+  if (RUNTIME_STATE_KEYS.has(keyPath)) return { valid: true };
 
   // Dynamic patterns — all sourced from shared config-schema (#2653).
   // Covers agent_skills.*, review.models.*, features.*,
diff --git a/sdk/src/query/config-schema.ts b/sdk/src/query/config-schema.ts
index 0029efa6a..6788a9ab4 100644
--- a/sdk/src/query/config-schema.ts
+++ b/sdk/src/query/config-schema.ts
@@ -71,6 +71,16 @@ export const VALID_CONFIG_KEYS: ReadonlySet<string> = new Set([
   'claude_md_assembly.mode',
   // #2517 — runtime-aware model profiles
   'runtime',
+  // #3162 — documented top-level key: controls model ID resolution for non-Claude runtimes
+  'resolve_model_ids',
+]);
+
+/**
+ * Internal runtime-state keys accepted by config-set workflows but not exposed
+ * as user-facing config options.
+ */
+export const RUNTIME_STATE_KEYS: ReadonlySet<string> = new Set([
+  'workflow._auto_chain_active',
 ]);
 
 /**
@@ -125,8 +135,9 @@ export const DYNAMIC_KEY_PATTERNS: readonly DynamicKeyPattern[] = [
   },
 ];
 
-/** Returns true if keyPath is a valid config key (exact or dynamic pattern). */
+/** Returns true if keyPath is a valid config key (exact, runtime-state, or dynamic pattern). */
 export function isValidConfigKeyPath(keyPath: string): boolean {
   if (VALID_CONFIG_KEYS.has(keyPath)) return true;
+  if (RUNTIME_STATE_KEYS.has(keyPath)) return true;
   return DYNAMIC_KEY_PATTERNS.some((p) => p.test(keyPath));
 }
diff --git a/tests/bug-2530-valid-config-keys.test.cjs b/tests/bug-2530-valid-config-keys.test.cjs
index 78e5c3ad1..bef5e4814 100644
--- a/tests/bug-2530-valid-config-keys.test.cjs
+++ b/tests/bug-2530-valid-config-keys.test.cjs
@@ -7,6 +7,8 @@
  * #2532 — workflow.ui_review is used in autonomous.md but missing from VALID_CONFIG_KEYS
  * #2533 — workflow.max_discuss_passes is used in discuss-phase.md but missing from VALID_CONFIG_KEYS
  * #2535 — sub_repos and plan_checker legacy keys need CONFIG_KEY_SUGGESTIONS migration hints
+ * #3162 — resolve_model_ids missing from VALID_CONFIG_KEYS; workflow._auto_chain_active must be
+ *          accepted by isValidConfigKey (written by workflows) without being user-visible
  */
 
 const { describe, test } = require('node:test');
@@ -14,7 +16,7 @@ const assert = require('node:assert/strict');
 const path = require('node:path');
 const { createTempProject, cleanup, runGsdTools } = require('./helpers.cjs');
 
-const { VALID_CONFIG_KEYS } = require('../get-shit-done/bin/lib/config-schema.cjs');
+const { VALID_CONFIG_KEYS, isValidConfigKey } = require('../get-shit-done/bin/lib/config-schema.cjs');
 
 describe('VALID_CONFIG_KEYS correctness', () => {
   test('#2530: workflow._auto_chain_active must not be in VALID_CONFIG_KEYS (internal state)', () => {
@@ -44,6 +46,21 @@ describe('VALID_CONFIG_KEYS correctness', () => {
       'workflow.max_discuss_passes is read in discuss-phase.md via gsd-sdk query config-get'
     );
   });
+
+  test('#3162: resolve_model_ids must be in VALID_CONFIG_KEYS (documented user-facing key)', () => {
+    assert.ok(
+      VALID_CONFIG_KEYS.has('resolve_model_ids'),
+      'resolve_model_ids is documented in CONFIGURATION.md and read by core.cjs/session-runner.ts'
+    );
+  });
+
+  test('#3162: workflow._auto_chain_active must be accepted by isValidConfigKey (written by workflows)', () => {
+    assert.strictEqual(
+      isValidConfigKey('workflow._auto_chain_active'),
+      true,
+      'workflow._auto_chain_active is written by plan-phase, execute-phase, discuss-phase, transition workflows via config-set'
+    );
+  });
 });
 
 describe('CONFIG_KEY_SUGGESTIONS migration hints (#2535)', () => {
diff --git a/tests/config-schema-sdk-parity.test.cjs b/tests/config-schema-sdk-parity.test.cjs
index 62aa98cfd..0741fd865 100644
--- a/tests/config-schema-sdk-parity.test.cjs
+++ b/tests/config-schema-sdk-parity.test.cjs
@@ -23,18 +23,22 @@ const fs = require('node:fs');
 const path = require('node:path');
 
 const ROOT = path.resolve(__dirname, '..');
-const { VALID_CONFIG_KEYS: CJS_KEYS, DYNAMIC_KEY_PATTERNS: CJS_PATTERNS } =
+const {
+  VALID_CONFIG_KEYS: CJS_KEYS,
+  RUNTIME_STATE_KEYS: CJS_RUNTIME_KEYS,
+  DYNAMIC_KEY_PATTERNS: CJS_PATTERNS,
+} =
   require('../get-shit-done/bin/lib/config-schema.cjs');
 
 const SDK_SCHEMA_PATH = path.join(ROOT, 'sdk', 'src', 'query', 'config-schema.ts');
 const SDK_SRC = fs.readFileSync(SDK_SCHEMA_PATH, 'utf8');
 
-function extractSdkKeys(src) {
-  const start = src.indexOf('VALID_CONFIG_KEYS');
-  assert.ok(start > -1, 'SDK config-schema.ts must export VALID_CONFIG_KEYS');
+function extractSdkSet(src, setName) {
+  const start = src.indexOf(setName);
+  assert.ok(start > -1, `SDK config-schema.ts must export ${setName}`);
   const setOpen = src.indexOf('new Set([', start);
   const setClose = src.indexOf('])', setOpen);
-  assert.ok(setOpen > -1 && setClose > -1, 'VALID_CONFIG_KEYS must be a new Set([...]) literal');
+  assert.ok(setOpen > -1 && setClose > -1, `${setName} must be a new Set([...]) literal`);
   const body = src.slice(setOpen + 'new Set(['.length, setClose);
   const keys = new Set();
   for (const match of body.matchAll(/'([^']+)'/g)) keys.add(match[1]);
@@ -52,7 +56,7 @@ function extractSdkPatternSources(src) {
 }
 
 test('#2653 — SDK VALID_CONFIG_KEYS matches CJS VALID_CONFIG_KEYS', () => {
-  const sdkKeys = extractSdkKeys(SDK_SRC);
+  const sdkKeys = extractSdkSet(SDK_SRC, 'VALID_CONFIG_KEYS');
   const missingInSdk = [...CJS_KEYS].filter((k) => !sdkKeys.has(k));
   const extraInSdk = [...sdkKeys].filter((k) => !CJS_KEYS.has(k));
   assert.deepStrictEqual(
@@ -69,6 +73,24 @@ test('#2653 — SDK VALID_CONFIG_KEYS matches CJS VALID_CONFIG_KEYS', () => {
   );
 });
 
+test('#3162 — SDK RUNTIME_STATE_KEYS matches CJS RUNTIME_STATE_KEYS', () => {
+  const sdkRuntimeKeys = extractSdkSet(SDK_SRC, 'RUNTIME_STATE_KEYS');
+  const missingInSdk = [...CJS_RUNTIME_KEYS].filter((k) => !sdkRuntimeKeys.has(k));
+  const extraInSdk = [...sdkRuntimeKeys].filter((k) => !CJS_RUNTIME_KEYS.has(k));
+  assert.deepStrictEqual(
+    missingInSdk,
+    [],
+    'CJS runtime-state keys missing from sdk/src/query/config-schema.ts:\n' +
+      missingInSdk.map((k) => '  ' + k).join('\n'),
+  );
+  assert.deepStrictEqual(
+    extraInSdk,
+    [],
+    'SDK runtime-state keys missing from get-shit-done/bin/lib/config-schema.cjs:\n' +
+      extraInSdk.map((k) => '  ' + k).join('\n'),
+  );
+});
+
 test('#2653 — SDK DYNAMIC_KEY_PATTERNS sources match CJS regex .source', () => {
   const sdkSources = new Set(extractSdkPatternSources(SDK_SRC));
   const cjsSources = CJS_PATTERNS.map((p) => {