diff --git a/gsd-core/workflows/onboard.md b/gsd-core/workflows/onboard.md
index 625372e3b..dbcd7c147 100644
--- a/gsd-core/workflows/onboard.md
+++ b/gsd-core/workflows/onboard.md
@@ -33,7 +33,7 @@ Parse JSON fields from `INIT`:
 - `commit_docs`, `text_mode`, `has_git`, `git_worktree_root`, `in_nested_subdir`
 
 Set:
-- `TEXT_MODE=true` if `--text` is present or `text_mode` is true.
+- `TEXT_MODE=true` if `--text` is present or `text_mode` is true. When `TEXT_MODE` is active, replace every `AskUserQuestion` call below with a plain-text numbered list and ask the user to type their choice number — required for non-Claude runtimes (OpenAI Codex, Gemini CLI, etc.) where `AskUserQuestion` is not available.
 - `ONBOARDING_ROOT={git_worktree_root || _GSD_RUNTIME_ROOT}`.
 
 If `has_git` and `in_nested_subdir` are true, warn that onboarding artifacts belong to the outer worktree at `git_worktree_root`. Do not run `git init`.
diff --git a/tests/runtime-launcher-parity.test.cjs b/tests/runtime-launcher-parity.test.cjs
index 8fada64b1..2f2448b7c 100644
--- a/tests/runtime-launcher-parity.test.cjs
+++ b/tests/runtime-launcher-parity.test.cjs
@@ -136,6 +136,22 @@ function collectAgentFiles() {
   return results;
 }
 
+/**
+ * A workflow/agent file "delegates to the shared resolver" when it pulls the
+ * canonical gsd_run preamble in from gsd-core/references/gsd-run-resolver.md via
+ * an @-include instead of inlining the snippet (see onboard.md / issue #1990).
+ *
+ * Such files are exempt from the inline-preamble parity checks (B / G / H and the
+ * runtime-home propagation checks): they intentionally do NOT inline the preamble
+ * — onboard-command.test.cjs even asserts the absence of the inline form. Their
+ * resolver correctness is guaranteed transitively by:
+ *   (1) onboard-command.test.cjs asserting the @-include is present, and
+ *   (2) the "resolver reference stays byte-equal to the snippet" guard (B2) below.
+ */
+function delegatesToResolverReference(content) {
+  return content.includes('references/gsd-run-resolver.md');
+}
+
 describe('runtime-launcher-parity (#373)', () => {
   // ─── (A) No retired GSD_SDK token ────────────────────────────────────────
   test('(A) no GSD_SDK token in any workflow .md file', () => {
@@ -170,6 +186,9 @@ describe('runtime-launcher-parity (#373)', () => {
     for (const f of files) {
       const rel = path.relative(WORKFLOWS_DIR, f);
       const content = fs.readFileSync(f, 'utf8');
+      // Files that delegate to the shared resolver reference (@-include) do not
+      // inline the preamble — exempt them (see delegatesToResolverReference / (B2)).
+      if (delegatesToResolverReference(content)) continue;
       const blocks = extractShellBlocks(content);
 
       // Collect all block lines in document order for flat analysis
@@ -226,6 +245,30 @@ describe('runtime-launcher-parity (#373)', () => {
     );
   });
 
+  // ─── (B2) Shared resolver reference stays byte-equal to the snippet ───────
+  // Workflows may delegate to gsd-core/references/gsd-run-resolver.md instead of
+  // inlining the preamble (see delegatesToResolverReference). That delegation is
+  // only safe if the reference's bash block is byte-equal to the canonical
+  // snippet — otherwise a delegating workflow (e.g. onboard.md) would silently
+  // ship a drifted resolver. This guard replaces the inline-preamble checks for
+  // those files.
+  test('(B2) references/gsd-run-resolver.md preamble is byte-equal to the canonical snippet', () => {
+    const preambleStr = expectedPreamble().join('\n');
+    const refPath = path.join(__dirname, '..', 'gsd-core', 'references', 'gsd-run-resolver.md');
+    const refContent = fs.readFileSync(refPath, 'utf8');
+    const refPreamble = extractShellBlocks(refContent)
+      .map((b) => b.lines.join('\n'))
+      .join('\n')
+      .trim();
+    assert.equal(
+      refPreamble,
+      preambleStr,
+      'gsd-core/references/gsd-run-resolver.md must contain the canonical gsd_run preamble ' +
+        'byte-equal to _runtime-launcher.snippet.sh. Re-copy the snippet into the reference so ' +
+        'workflows that delegate to it via @-include ship the current resolver.',
+    );
+  });
+
   // ─── (C) Space-safe behavioral test ──────────────────────────────────────
   test('(C) gsd_run works with a RUNTIME_DIR path containing spaces', () => {
     // Create temp dir whose path contains a space
@@ -402,6 +445,7 @@ describe('runtime-launcher-parity (#373)', () => {
       const content = fs.readFileSync(f, 'utf8');
       const blocks = extractShellBlocks(content);
       const allBlockLines = blocks.flatMap((b) => b.lines);
+      if (delegatesToResolverReference(content)) continue;
       const fileHasGsdRun = allBlockLines.some((l) => /\bgsd_run\b/.test(l));
       if (!fileHasGsdRun) continue;
       const allContent = allBlockLines.join('\n');
@@ -433,6 +477,7 @@ describe('runtime-launcher-parity (#373)', () => {
       const content = fs.readFileSync(f, 'utf8');
       const blocks = extractShellBlocks(content);
       const allBlockLines = blocks.flatMap((b) => b.lines);
+      if (delegatesToResolverReference(content)) continue;
       const fileHasGsdRun = allBlockLines.some((l) => /\bgsd_run\b/.test(l));
       if (!fileHasGsdRun) continue;
       if (!allBlockLines.join('\n').includes(CODEX_HOME_PROBE)) {
@@ -1346,6 +1391,7 @@ describe('bug-891: non-Claude runtime home fallback arms', () => {
       const content = fs.readFileSync(f, 'utf8');
       const blocks = extractShellBlocks(content);
       const allBlockLines = blocks.flatMap((b) => b.lines);
+      if (delegatesToResolverReference(content)) continue;
       const fileHasGsdRun = allBlockLines.some((l) => /\bgsd_run\b/.test(l));
       if (!fileHasGsdRun) continue;
       const allContent = allBlockLines.join('\n');