diff --git a/AGENTS.md b/AGENTS.md
index bad0d36..c23b2f3 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -21,6 +21,7 @@ When writing complex features or significant refactors, use an ExecPlan (as desc
   2. grouped edits or grouped repo actions
   3. focused verification
   4. compact summary
+- Low output alone is not a defect. A bounded run that finishes in roughly <=10 steps is usually fine; low output stretched across 20+ steps with rising input is fragmentation.
 - Treat obvious follow-on actions as part of the active phase; do not stop for tiny internal checkpoints.
 - If context grows or the session becomes fragmented, write a short working summary and continue from it.
 
@@ -30,12 +31,14 @@ When writing complex features or significant refactors, use an ExecPlan (as desc
 - Prefer targeted reads: `rg`, `head`, `tail`, `git diff`, and exact line ranges.
 - Keep command output compact and relevant.
 - Avoid repeated status checks unless something changed.
+- Treat repeated `sed` / `cat` peeks, tiny diagnostic retries, and repeated `write_stdin` as red flags. When they appear, stop the probe loop and reset to one bounded phase.
 
 ### Command Discipline
 
 - Batch related shell commands whenever safe.
 - Prefer one-shot non-interactive commands, scripts, or exact invocations over interactive loops or repeated stdin driving.
 - For diagnosis, gather the relevant evidence in one pass, then summarize once.
+- If the session turns fragmented, collapse back to inspect once, patch once, verify once, and summarize once.
 
 ### Git And PR Workflow
 
diff --git a/openspec/changes/tighten-token-fragmentation-prompts/proposal.md b/openspec/changes/tighten-token-fragmentation-prompts/proposal.md
new file mode 100644
index 0000000..7354e27
--- /dev/null
+++ b/openspec/changes/tighten-token-fragmentation-prompts/proposal.md
@@ -0,0 +1,7 @@
+# Proposal: tighten Guardex token-fragmentation prompts
+
+Guardex already prefers phase-based execution, but the copied `gx prompt` task loop still underspecifies the anti-fragmentation pattern. This change makes the repo contract and prompt output teach the stronger classifier: low output alone is fine when the run is bounded, while long low-output sessions with repeated peeks or `write_stdin` loops are fragmentation.
+
+- add the bounded-vs-fragmented classifier to `AGENTS.md`
+- teach `gx prompt` to say inspect once, patch once, verify once, then finish
+- lock the prompt wording with focused tests
diff --git a/openspec/changes/tighten-token-fragmentation-prompts/tasks.md b/openspec/changes/tighten-token-fragmentation-prompts/tasks.md
new file mode 100644
index 0000000..c9d5406
--- /dev/null
+++ b/openspec/changes/tighten-token-fragmentation-prompts/tasks.md
@@ -0,0 +1,22 @@
+## 1. Spec
+
+- [x] 1.1 Capture why Guardex prompt surfaces should blame long fragmented runs, not low output alone.
+
+## 2. Implementation
+
+- [x] 2.1 Update `AGENTS.md` with the bounded-vs-fragmented classifier and stop-loop guidance.
+- [x] 2.2 Update `src/context.js` task-loop prompt text to push inspect-once / patch-once / verify-once execution.
+- [x] 2.3 Update `test/prompt.test.js` to lock the new prompt wording.
+
+## 3. Verification
+
+- [x] 3.1 Run `node --test test/prompt.test.js`.
+- [x] 3.2 Run `openspec validate --specs`.
+
+Verification evidence:
+- `node --test test/prompt.test.js` (pass)
+- `openspec validate --specs` (no items found to validate)
+
+## 4. Cleanup
+
+- [ ] 4.1 Commit, push, open/update PR, merge, and clean up the worktree.
diff --git a/src/context.js b/src/context.js
index 2ff298e..1d667b6 100644
--- a/src/context.js
+++ b/src/context.js
@@ -425,7 +425,8 @@ const AI_SETUP_PARTS = [
     label: 'Task loop',
     promptLines: [
       'gx branch start "<task>" "<agent>"',
-      'then gx locks claim --branch "<agent-branch>" <file...> -> gx branch finish',
+      'then gx locks claim --branch "<agent-branch>" <file...> -> inspect once -> patch once -> verify once -> gx branch finish',
+      'batch discovery, git/PR, and CI by phase; avoid repeated peeks or stdin loops',
     ],
     execLines: [
       'gx branch start "<task>" "<agent>"',
diff --git a/test/prompt.test.js b/test/prompt.test.js
index 1ac14ef..7d983da 100644
--- a/test/prompt.test.js
+++ b/test/prompt.test.js
@@ -73,6 +73,8 @@ test('prompt outputs AI setup instructions', () => {
   assert.match(result.stdout, /gx doctor/);
   assert.match(result.stdout, /gx branch start/);
   assert.match(result.stdout, /gx locks claim/);
+  assert.match(result.stdout, /inspect once -> patch once -> verify once -> gx branch finish/);
+  assert.match(result.stdout, /avoid repeated peeks or stdin loops/);
   assert.match(result.stdout, /gx finish --all/);
   assert.match(result.stdout, /\/opsx:propose/);
   assert.match(result.stdout, /https:\/\/github\.com\/apps\/pull/);
@@ -101,6 +103,7 @@ test('prompt --part outputs only the selected checklist slices', () => {
   assert.equal(result.status, 0, result.stderr || result.stdout);
   assert.match(result.stdout, /^Task loop:/m);
   assert.match(result.stdout, /gx branch start "<task>" "<agent>"/);
+  assert.match(result.stdout, /inspect once -> patch once -> verify once -> gx branch finish/);
   assert.match(result.stdout, /^Finish:/m);
   assert.match(result.stdout, /gx finish --all/);
   assert.doesNotMatch(result.stdout, /GitGuardex \(gx\) setup checklist/);