diff --git a/docs/slo.md b/docs/slo.md
index 38f83b740..5d7210d33 100644
--- a/docs/slo.md
+++ b/docs/slo.md
@@ -51,15 +51,18 @@ No exporter or external data flow is added by this document — recommendations
   as a follow-up (see below); recovery guidance is in the same
   [`runbooks/incident-response-unsafe-mission-merge.md`](../runbooks/incident-response-unsafe-mission-merge.md).
   **Third known exception**: `Validate Mission Schema` itself has a broader
-  version of this same gap — it never validates `runbooks/**` at all, on
-  *either* trigger. Its PR-mode `git diff` pathspec covers only
-  `fixes/**/*.json`/`*.yaml`/`*.yml`, so a `runbooks/**`-only PR resolves to
-  an empty file list and the validation step is skipped (job still reports
-  green). And its scheduled/push `--all` mode
-  (`scripts/validate-schema.mjs`) only calls `discoverMissionFiles('fixes')`
-  — the weekly cadence sweep never walks `runbooks/**` either. The 10
-  `runbooks/*.json` mission files therefore have zero automated schema
-  validation coverage on any trigger. Also tracked as a follow-up (see
+  version of this same gap — it never validated `runbooks/**` at all, on
+  *either* trigger. Its PR-mode `git diff` pathspec covered only
+  `fixes/**/*.json`/`*.yaml`/`*.yml`, so a `runbooks/**`-only PR resolved to
+  an empty file list and the validation step was skipped (job still reported
+  green). The scheduled/push `--all` mode side of this gap
+  (`scripts/validate-schema.mjs` only walking `fixes/`) has been fixed — it
+  now also discovers mission files under `runbooks/`, so the weekly cadence
+  sweep validates all 10 `runbooks/*.json` files. The PR-mode pathspec still
+  needs the corresponding `runbooks/**/*.json`/`*.yaml`/`*.yml` globs added
+  to `.github/workflows/validate-schema.yml`'s "Find changed files (PR
+  only)" step; that edit is prepared but requires `workflows` permission
+  this contribution's credentials do not have. Tracked as a follow-up (see
   below); recovery guidance is in the same
   [`runbooks/incident-response-unsafe-mission-merge.md`](../runbooks/incident-response-unsafe-mission-merge.md).
   **Fourth known exception**: `KB Quality Enforcement`
@@ -143,14 +146,19 @@ dangerous commands" step. Also filed separately as a `[operations]` issue
 for the same `workflows`-permission reason.
 
 The section 2 "third known exception" above (`validate-schema.yml` never
-validating `runbooks/**`, on PRs or on its scheduled/push `--all` sweep)
-also requires editing that workflow's PR-mode `git diff` pathspec and
-`scripts/validate-schema.mjs`'s `--all` branch to also discover files under
-`runbooks/`. Also filed separately as a `[operations]` issue (#3255) for the
-same `workflows`-permission reason.
+validating `runbooks/**`) is now partially resolved:
+`scripts/validate-schema.mjs`'s `--all` branch has been updated to also
+discover files under `runbooks/`, so the weekly/push sweep now covers all
+10 `runbooks/*.json` files. The remaining piece — extending
+`validate-schema.yml`'s PR-mode `git diff` pathspec with the same
+`runbooks/**/*.json`/`*.yaml`/`*.yml` globs so a `runbooks/**`-only PR is
+no longer skipped — still requires `workflows` permission this
+contribution's credentials do not have. Tracked in `[operations]` issue
+#3255 until that pathspec change lands.
 
 ## References
 
+
 - [`runbooks/incident-response-index-publish-failure.md`](../runbooks/incident-response-index-publish-failure.md)
 - [`runbooks/incident-response-search-state-corruption.md`](../runbooks/incident-response-search-state-corruption.md) — covers the `CNCF Mission Generation` workflow's separate direct-to-`master` push of `search-state.json`, which (unlike `fixes/index.json`) has no content-validation gate at all
 - [`runbooks/incident-response-unsafe-mission-merge.md`](../runbooks/incident-response-unsafe-mission-merge.md) — covers the `CNCF Mission Generation` workflow's `--admin` auto-merge bypassing `Mission Safety Scan` and `Validate Mission Schema`, and separately, `Mission Safety Scan`'s own false-green on `runbooks/**`-only PRs
diff --git a/scripts/__tests__/validate-schema-cli-discover.test.mjs b/scripts/__tests__/validate-schema-cli-discover.test.mjs
index 5604244d3..bdbeb6637 100644
--- a/scripts/__tests__/validate-schema-cli-discover.test.mjs
+++ b/scripts/__tests__/validate-schema-cli-discover.test.mjs
@@ -191,6 +191,49 @@ describe('validate-schema.mjs --all discovery', () => {
     })
   })
 
+  it('also discovers mission files under runbooks/, in addition to fixes/', () => {
+    // Guards against the false-green regression where --all only ever
+    // scanned fixes/: runbooks/*.json uses the same kc-mission-v1 schema
+    // (see runbooks/README.md) but previously had zero scheduled/push
+    // validation coverage because ALL_MODE_DIRS omitted it.
+    withTempDir(dir => {
+      mkdirSync(join(dir, 'fixes'), { recursive: true })
+      mkdirSync(join(dir, 'runbooks'), { recursive: true })
+      writeFileSync(join(dir, 'fixes', 'a.json'), JSON.stringify(VALID_MISSION))
+      writeFileSync(join(dir, 'runbooks', 'b.json'), JSON.stringify(VALID_MISSION))
+
+      const result = runCli(dir, ['--all'])
+
+      expect(result.status).toBe(0)
+      expect(result.stdout).toMatch(/Discovered 2 mission files to validate\./)
+      expect(result.stdout).toContain('a.json')
+      expect(result.stdout).toContain('b.json')
+
+      const summary = parseSummary(result.stdout)
+      expect(summary).toMatchObject({
+        trigger: 'all',
+        total: 2,
+        validCount: 2,
+        invalidCount: 0,
+      })
+    })
+  })
+
+  it('--all mode still works when runbooks/ does not exist (no crash)', () => {
+    // ALL_MODE_DIRS must tolerate a missing runbooks/ directory rather than
+    // throwing ENOENT, so this doesn't regress environments/checkouts that
+    // don't have one.
+    withTempDir(dir => {
+      mkdirSync(join(dir, 'fixes'), { recursive: true })
+      writeFileSync(join(dir, 'fixes', 'a.json'), JSON.stringify(VALID_MISSION))
+
+      const result = runCli(dir, ['--all'])
+
+      expect(result.status).toBe(0)
+      expect(result.stdout).toMatch(/Discovered 1 mission files to validate\./)
+    })
+  })
+
   it('sets summary trigger to "all" and level to "error" when a discovered file is invalid', () => {
     // Guards the trigger vs level distinction: trigger reflects the CLI
     // switch, level reflects the outcome. A regression that swapped them
diff --git a/scripts/validate-schema.mjs b/scripts/validate-schema.mjs
index dc850866f..8a3ccdc02 100644
--- a/scripts/validate-schema.mjs
+++ b/scripts/validate-schema.mjs
@@ -1,5 +1,5 @@
 #!/usr/bin/env node
-import { readFileSync, readdirSync } from 'fs';
+import { readFileSync, readdirSync, existsSync } from 'fs';
 import { join } from 'path';
 import * as yaml from 'js-yaml';
 import { validateMissionExport } from './scanner.mjs';
@@ -13,6 +13,14 @@ const MISSION_EXTENSIONS = new Set(['.json', '.yaml', '.yml']);
 /** Files to skip when discovering all missions */
 const SKIP_FILENAMES = new Set(['index.json']);
 
+/**
+ * Directories scanned in `--all` mode. `runbooks/` holds the same
+ * `kc-mission-v1` schema format as `fixes/` (see runbooks/README.md) but was
+ * previously omitted here, leaving its mission files with no scheduled/push
+ * schema-validation coverage.
+ */
+const ALL_MODE_DIRS = ['fixes', 'runbooks'];
+
 /**
  * Recursively discovers all mission files under the given directory.
  * Returns an array of relative file paths.
@@ -99,8 +107,11 @@ function main() {
 
   let files;
   if (args.includes('--all')) {
-    // Discover all mission files under fixes/ (used for push/schedule/dispatch)
-    files = discoverMissionFiles('fixes');
+    // Discover all mission files under fixes/ and runbooks/ (used for
+    // push/schedule/dispatch full sweeps).
+    files = ALL_MODE_DIRS
+      .filter(dir => existsSync(dir))
+      .flatMap(dir => discoverMissionFiles(dir));
     console.log(`Discovered ${files.length} mission files to validate.\n`);
   } else {
     files = args.flatMap(a => a.split(/\s+/)).filter(Boolean);