diff --git a/tests/bug-3810-no-gsd-sdk-runtime-refs.test.cjs b/tests/bug-3810-no-gsd-sdk-runtime-refs.test.cjs
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+// allow-test-rule: source-text-is-the-product
+// Runtime prompt/hook files are deployed verbatim — their text IS what the
+// runtime loads and executes. Asserting that text carries no retired `gsd-sdk`
+// reference tests the deployed contract, which no behavioral seam can observe
+// (there is no runtime API that enumerates "did any shipped prompt name the
+// removed SDK binary").
+
+/**
+ * Regression guard: no `gsd-sdk` references in runtime-facing surfaces (#339).
+ *
+ * The `@opengsd/gsd-sdk` package and its `gsd-sdk` binary were retired (ADR 0174,
+ * #191). The bulk runtime cleanup is already done — this test locks it in so a
+ * `gsd-sdk` / `GSD_SDK` reference cannot creep back into a shipped prompt or hook
+ * and re-introduce drift between the documented surface and the supported
+ * `gsd-tools` binary.
+ *
+ * Scope: runtime surfaces only — the prompts and hooks the installer ships into
+ * a user's runtime config dir. Explicitly NOT covered here:
+ *   - `bin/install.js` — installer code, not a runtime-deployed prompt/hook
+ *     surface. (It carries zero `gsd-sdk` references today; the SDK-shim
+ *     verification subsystem was removed in #515 and the shim retired in #522.)
+ *   - `gsd-core/bin/` — executable library code, not deployed prompt text; it
+ *     may legitimately reference the SDK retirement in comments.
+ *   - `tests/`, `docs/`, `.changeset/`, CI/lint scripts — legitimately reference
+ *     the SDK retirement as history or detect its stale artifacts.
+ *
+ * Complements `tests/gsd-tools-path-refs.test.cjs`, which only catches the
+ * `gsd-sdk query` binary-invocation form; this catches ANY runtime reference.
+ */
+
+'use strict';
+
+const { describe, test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+
+const REPO_ROOT = path.join(__dirname, '..');
+
+// Runtime surfaces the installer ships. Each entry is { dir, exts } — dir is
+// repo-relative, exts is the set of file extensions whose text is deployed.
+const RUNTIME_SURFACES = [
+  // .md prompts plus the non-.md runtime artifacts this dir also ships:
+  // _runtime-launcher.snippet.sh (the canonical launcher synced into every hook
+  // by scripts/sync-runtime-launcher.cjs) and discuss-phase/templates/*.json
+  // (loaded at runtime by discuss-phase.md). Scanning only .md left these two
+  // deployed files uncovered. (#691 review)
+  { dir: path.join('gsd-core', 'workflows'), exts: ['.md', '.sh', '.json'] },
+  { dir: path.join('gsd-core', 'references'), exts: ['.md'] },
+  // Prompt surfaces the installer deep-copies and the runtime loads via
+  // `@~/.claude/gsd-core/templates/*.md` anchors in workflows/commands; the
+  // lone config.json under templates/ ships too. (#691 review)
+  { dir: path.join('gsd-core', 'templates'), exts: ['.md', '.json'] },
+  { dir: path.join('gsd-core', 'contexts'), exts: ['.md'] },
+  { dir: path.join('commands', 'gsd'), exts: ['.md'] },
+  { dir: 'agents', exts: ['.md'] },
+  // Hooks ship as executable text (.js/.cjs/.sh). `hooks/dist/` is a gitignored
+  // build artifact regenerated from these sources, so scanning the sources is
+  // sufficient and avoids asserting against generated copies.
+  { dir: 'hooks', exts: ['.js', '.cjs', '.sh'], skipDirs: ['dist'] },
+];
+
+// Matches every casing/separator variant of the retired SDK token:
+// gsd-sdk, gsd_sdk, GSD-SDK, GSD_SDK, etc.
+const SDK_REF = /gsd[-_]sdk/i;
+
+/**
+ * Recursively collect files under `absDir` whose extension is in `exts`,
+ * skipping any directory name listed in `skipDirs`.
+ */
+function collectFiles(absDir, exts, skipDirs) {
+  if (!fs.existsSync(absDir)) return [];
+  const out = [];
+  for (const entry of fs.readdirSync(absDir, { withFileTypes: true })) {
+    if (entry.isDirectory()) {
+      if (skipDirs.includes(entry.name)) continue;
+      out.push(...collectFiles(path.join(absDir, entry.name), exts, skipDirs));
+    } else if (entry.isFile() && exts.includes(path.extname(entry.name))) {
+      out.push(path.join(absDir, entry.name));
+    }
+  }
+  return out;
+}
+
+function rel(file) {
+  return path.relative(REPO_ROOT, file).split(path.sep).join('/');
+}
+
+describe('#339 no gsd-sdk references in runtime surfaces', () => {
+  test('shipped prompts and hooks carry no retired gsd-sdk reference', () => {
+    const violations = [];
+
+    for (const { dir, exts, skipDirs = [] } of RUNTIME_SURFACES) {
+      const files = collectFiles(path.join(REPO_ROOT, dir), exts, skipDirs);
+      for (const file of files) {
+        const lines = fs.readFileSync(file, 'utf-8').split(/\r?\n/);
+        for (let i = 0; i < lines.length; i++) {
+          if (SDK_REF.test(lines[i])) {
+            violations.push(`${rel(file)}:${i + 1}: ${lines[i].trim()}`);
+          }
+        }
+      }
+    }
+
+    assert.strictEqual(
+      violations.length,
+      0,
+      'Runtime surfaces must not reference the retired gsd-sdk binary/package — ' +
+        'use gsd-tools instead.\nViolations:\n' + violations.join('\n')
+    );
+  });
+
+  test('at least one file per configured extension is scanned (guards against an empty sweep)', () => {
+    // A path typo, directory rename, or stale extension could silently make
+    // collectFiles() return [] for part of a surface, turning the guard above
+    // into a no-op that always passes. Checking per-surface isn't enough: for
+    // gsd-core/workflows the .md files alone keep a per-surface count > 0, so
+    // dropping .sh/.json would stop covering _runtime-launcher.snippet.sh and
+    // discuss-phase/templates/*.json while the test stayed green. Assert each
+    // configured extension actually resolves to scanned files. (#691 review)
+    for (const { dir, exts, skipDirs = [] } of RUNTIME_SURFACES) {
+      for (const ext of exts) {
+        const count = collectFiles(path.join(REPO_ROOT, dir), [ext], skipDirs).length;
+        assert.ok(
+          count > 0,
+          `Runtime surface "${dir}" resolved to 0 "${ext}" files — the path may ` +
+            'have moved or the extension is stale; update RUNTIME_SURFACES so the ' +
+            'guard keeps covering it.'
+        );
+      }
+    }
+  });
+});