diff --git a/docs/development.md b/docs/development.md
index abfbae4..8f34a4a 100644
--- a/docs/development.md
+++ b/docs/development.md
@@ -79,7 +79,13 @@ Et parallelt, uavhengig spor fra sitemap-discoveren: oppdage at Microsoft har pu
    node scripts/kb-update/detect-courses.mjs --data-dir DIR  # omdiriger IO (tester)
    ```
 
-   Fail-soft: mangler creds → `status:"skipped"` + exit 0; vedvarende nettverksfeil → `status:"error"` + exit 0. Opt-in inni opt-in: steget kjøres kun av scheduleren når `include_course_detection: true` (default `false`) — sett nøkkelen manuelt i `~/.claude/ms-ai-architect/ms-ai-architect.local.md`.
+   Fail-soft: mangler creds → `status:"skipped"` + exit 0; vedvarende nettverksfeil → `status:"error"` + exit 0. Opt-in inni opt-in: steget kjøres kun av scheduleren når `include_course_detection: true` (default `false`). Sett flagget via eier-CLI (skriver den gitignored local.md atomisk, bevarer øvrige nøkler):
+
+   ```bash
+   node scripts/kb-update/write-schedule-config.mjs --enabled true --cadence daily --courses true
+   ```
+
+   `--courses` er valgfritt — utelat det for å la en verdi satt andre steder stå urørt.
 
 2. **SessionStart-surfacing (read-only).** `session-start-context.mjs` leser `course-detection-report.json` og viser en one-liner via `summarizeCourses` («Kurs-signaler: N nye / M endrede kurs i dekkede produkter. Kjør /architect:kb-update») — speiler skill-signaler-blokka. `removed` er kun et informasjonssignal i rapporten, aldri en surfacet lead (spec §4.2). Hooken spawner ingenting for kurs-sporet.
 
diff --git a/scripts/kb-update/write-schedule-config.mjs b/scripts/kb-update/write-schedule-config.mjs
index f2abe57..2884800 100644
--- a/scripts/kb-update/write-schedule-config.mjs
+++ b/scripts/kb-update/write-schedule-config.mjs
@@ -18,8 +18,11 @@
 //
 //   node scripts/kb-update/write-schedule-config.mjs --enabled true --cadence daily
 //   node scripts/kb-update/write-schedule-config.mjs --enabled false --cadence interval
+//   node scripts/kb-update/write-schedule-config.mjs --enabled true --cadence daily --courses true
 //
-// --home <dir> overrides the home dir (tests). Prints the resolved config path.
+// --courses true|false toggles include_course_detection (Spor C / C3 opt-in);
+// OPTIONAL — omit it to leave a value set elsewhere untouched. --home <dir>
+// overrides the home dir (tests). Prints the resolved config path.
 
 import { existsSync, readFileSync, mkdirSync } from 'node:fs';
 import { join } from 'node:path';
@@ -34,6 +37,7 @@ function parseArgs(argv) {
   for (let i = 0; i < argv.length; i++) {
     if (argv[i] === '--enabled') out.enabled = argv[++i];
     else if (argv[i] === '--cadence') out.cadence = argv[++i];
+    else if (argv[i] === '--courses') out.courses = argv[++i];
     else if (argv[i] === '--home') out.home = argv[++i];
   }
   return out;
@@ -41,10 +45,10 @@ function parseArgs(argv) {
 
 /**
  * Write (merge onto) the user-owned scheduler config from onboarding answers.
- * @param {{enabled: boolean|string, cadence: string, home?: string}} args
+ * @param {{enabled: boolean|string, cadence: string, courses?: boolean|string, home?: string}} args
  * @returns {{configPath: string, config: object}}
  */
-export function writeScheduleConfig({ enabled, cadence, home = homedir() }) {
+export function writeScheduleConfig({ enabled, cadence, courses, home = homedir() }) {
   const configPath = resolveConfigPath(home);
   const existing = existsSync(configPath) ? readFileSync(configPath, 'utf8') : '';
   const parsed = parseScheduleConfig(existing); // existing values (or OFF defaults)
@@ -58,6 +62,13 @@ export function writeScheduleConfig({ enabled, cadence, home = homedir() }) {
     os_scheduler_cadence: cadence === 'interval' ? 'interval' : 'daily',
   };
 
+  // --courses is OPTIONAL (opt-in inside opt-in): only override
+  // include_course_detection when the flag was explicitly supplied, so a value
+  // set elsewhere survives an onboarding rewrite that omits it.
+  if (courses !== undefined) {
+    merged.include_course_detection = courses === true || courses === 'true';
+  }
+
   mkdirSync(resolveUserDataDir(home), { recursive: true });
   backupFile(configPath, join(resolveUserDataDir(home), '.backups')); // no-op if absent
   atomicWriteSync(configPath, serializeScheduleConfig(merged));
@@ -66,10 +77,11 @@ export function writeScheduleConfig({ enabled, cadence, home = homedir() }) {
 
 // CLI entry — only when run directly (not when imported by tests).
 if (import.meta.url === `file://${process.argv[1]}`) {
-  const { enabled, cadence, home } = parseArgs(process.argv.slice(2));
-  const { configPath, config } = writeScheduleConfig({ enabled, cadence, home });
+  const { enabled, cadence, courses, home } = parseArgs(process.argv.slice(2));
+  const { configPath, config } = writeScheduleConfig({ enabled, cadence, courses, home });
   console.log(configPath);
   console.error(
-    `scheduled_detection: enabled=${config.enabled} os_scheduler_cadence=${config.os_scheduler_cadence} (interval_days=${config.interval_days})`,
+    `scheduled_detection: enabled=${config.enabled} os_scheduler_cadence=${config.os_scheduler_cadence} ` +
+      `(interval_days=${config.interval_days} include_course_detection=${config.include_course_detection})`,
   );
 }
diff --git a/tests/kb-update/test-detection-schedule.test.mjs b/tests/kb-update/test-detection-schedule.test.mjs
index cb2552b..62385db 100644
--- a/tests/kb-update/test-detection-schedule.test.mjs
+++ b/tests/kb-update/test-detection-schedule.test.mjs
@@ -201,6 +201,46 @@ test('writeScheduleConfig — merge preserves pre-existing keys (interval_days)
   }
 });
 
+// --- C3 (3): --courses flag wires include_course_detection from the CLI ---
+test('writeScheduleConfig — --courses true sets include_course_detection (opt-in inside opt-in)', () => {
+  const home = mkdtempSync(join(tmpdir(), 'home-'));
+  try {
+    writeScheduleConfig({ enabled: true, cadence: 'daily', courses: true, home });
+    const cfg = parseScheduleConfig(readFileSync(resolveConfigPath(home), 'utf8'));
+    assert.equal(cfg.include_course_detection, true);
+  } finally {
+    rmSync(home, { recursive: true, force: true });
+  }
+});
+
+test('writeScheduleConfig — coerces the --courses string flag (CLI args arrive as strings)', () => {
+  const home = mkdtempSync(join(tmpdir(), 'home-'));
+  try {
+    writeScheduleConfig({ enabled: true, cadence: 'daily', courses: 'true', home });
+    assert.equal(parseScheduleConfig(readFileSync(resolveConfigPath(home), 'utf8')).include_course_detection, true);
+    writeScheduleConfig({ enabled: true, cadence: 'daily', courses: 'false', home });
+    assert.equal(parseScheduleConfig(readFileSync(resolveConfigPath(home), 'utf8')).include_course_detection, false);
+  } finally {
+    rmSync(home, { recursive: true, force: true });
+  }
+});
+
+test('writeScheduleConfig — omitting --courses preserves a pre-existing include_course_detection', () => {
+  const home = mkdtempSync(join(tmpdir(), 'home-'));
+  try {
+    mkdirSync(resolveUserDataDir(home), { recursive: true });
+    writeFileSync(
+      resolveConfigPath(home),
+      'scheduled_detection:\n  enabled: true\n  include_course_detection: true\n',
+    );
+    writeScheduleConfig({ enabled: false, cadence: 'interval', home }); // no `courses` arg
+    const cfg = parseScheduleConfig(readFileSync(resolveConfigPath(home), 'utf8'));
+    assert.equal(cfg.include_course_detection, true, 'non-owned key preserved when --courses is omitted');
+  } finally {
+    rmSync(home, { recursive: true, force: true });
+  }
+});
+
 test('writeScheduleConfig — backs up an existing config before overwriting it', () => {
   const home = mkdtempSync(join(tmpdir(), 'home-'));
   try {