diff --git a/scripts/resolvers/preamble/generate-completion-status.ts b/scripts/resolvers/preamble/generate-completion-status.ts
index 56841caeb..8b93ff503 100644
--- a/scripts/resolvers/preamble/generate-completion-status.ts
+++ b/scripts/resolvers/preamble/generate-completion-status.ts
@@ -73,11 +73,15 @@ fi
 if [ "$_TEL" != "off" ] && [ -x ~/.claude/skills/gstack/bin/gstack-telemetry-log ]; then
   ~/.claude/skills/gstack/bin/gstack-telemetry-log \\
     --skill "SKILL_NAME" --duration "$_TEL_DUR" --outcome "OUTCOME" \\
-    --used-browse "USED_BROWSE" --session-id "$_SESSION_ID" 2>/dev/null &
+    --used-browse "USED_BROWSE" --session-id "$_SESSION_ID" \\
+    --error-message "ERROR_MESSAGE" --failed-step "FAILED_STEP" 2>/dev/null &
 fi
 \`\`\`
 
 Replace \`SKILL_NAME\`, \`OUTCOME\`, and \`USED_BROWSE\` before running.
+Replace \`ERROR_MESSAGE\` with a short description of the error (if outcome is error,
+otherwise use empty string ""), and \`FAILED_STEP\` with the step name or number where
+the failure occurred (if outcome is error, otherwise use empty string "").
 
 ## Plan Status Footer
 
diff --git a/supabase/functions/telemetry-ingest/index.ts b/supabase/functions/telemetry-ingest/index.ts
index acf994eab..f4e9cc8a9 100644
--- a/supabase/functions/telemetry-ingest/index.ts
+++ b/supabase/functions/telemetry-ingest/index.ts
@@ -16,6 +16,8 @@ interface TelemetryEvent {
   duration_s?: number;
   outcome: string;
   error_class?: string;
+  error_message?: string;
+  failed_step?: string;
   used_browse?: boolean;
   sessions?: number;
   installation_id?: string;
@@ -93,6 +95,8 @@ Deno.serve(async (req) => {
         duration_s: typeof event.duration_s === "number" ? event.duration_s : null,
         outcome: String(event.outcome).slice(0, 20),
         error_class: event.error_class ? String(event.error_class).slice(0, 100) : null,
+        error_message: event.error_message ? String(event.error_message).slice(0, 500) : null,
+        failed_step: event.failed_step ? String(event.failed_step).slice(0, 100) : null,
         used_browse: event.used_browse === true,
         concurrent_sessions: typeof event.sessions === "number" ? event.sessions : 1,
         installation_id: event.installation_id ? String(event.installation_id).slice(0, 64) : null,
diff --git a/test/fixtures/golden/claude-ship-SKILL.md b/test/fixtures/golden/claude-ship-SKILL.md
index abc16e7d0..319dd43fc 100644
--- a/test/fixtures/golden/claude-ship-SKILL.md
+++ b/test/fixtures/golden/claude-ship-SKILL.md
@@ -794,11 +794,15 @@ fi
 if [ "$_TEL" != "off" ] && [ -x ~/.claude/skills/gstack/bin/gstack-telemetry-log ]; then
   ~/.claude/skills/gstack/bin/gstack-telemetry-log \
     --skill "SKILL_NAME" --duration "$_TEL_DUR" --outcome "OUTCOME" \
-    --used-browse "USED_BROWSE" --session-id "$_SESSION_ID" 2>/dev/null &
+    --used-browse "USED_BROWSE" --session-id "$_SESSION_ID" \
+    --error-message "ERROR_MESSAGE" --failed-step "FAILED_STEP" 2>/dev/null &
 fi
 ```
 
 Replace `SKILL_NAME`, `OUTCOME`, and `USED_BROWSE` before running.
+Replace `ERROR_MESSAGE` with a short description of the error (if outcome is error,
+otherwise use empty string ""), and `FAILED_STEP` with the step name or number where
+the failure occurred (if outcome is error, otherwise use empty string "").
 
 ## Plan Status Footer
 
diff --git a/test/fixtures/golden/codex-ship-SKILL.md b/test/fixtures/golden/codex-ship-SKILL.md
index 700247096..920e896a6 100644
--- a/test/fixtures/golden/codex-ship-SKILL.md
+++ b/test/fixtures/golden/codex-ship-SKILL.md
@@ -780,11 +780,15 @@ fi
 if [ "$_TEL" != "off" ] && [ -x $GSTACK_ROOT/bin/gstack-telemetry-log ]; then
   $GSTACK_ROOT/bin/gstack-telemetry-log \
     --skill "SKILL_NAME" --duration "$_TEL_DUR" --outcome "OUTCOME" \
-    --used-browse "USED_BROWSE" --session-id "$_SESSION_ID" 2>/dev/null &
+    --used-browse "USED_BROWSE" --session-id "$_SESSION_ID" \
+    --error-message "ERROR_MESSAGE" --failed-step "FAILED_STEP" 2>/dev/null &
 fi
 ```
 
 Replace `SKILL_NAME`, `OUTCOME`, and `USED_BROWSE` before running.
+Replace `ERROR_MESSAGE` with a short description of the error (if outcome is error,
+otherwise use empty string ""), and `FAILED_STEP` with the step name or number where
+the failure occurred (if outcome is error, otherwise use empty string "").
 
 ## Plan Status Footer
 
diff --git a/test/fixtures/golden/factory-ship-SKILL.md b/test/fixtures/golden/factory-ship-SKILL.md
index 69c6013db..2c0bd0077 100644
--- a/test/fixtures/golden/factory-ship-SKILL.md
+++ b/test/fixtures/golden/factory-ship-SKILL.md
@@ -782,11 +782,15 @@ fi
 if [ "$_TEL" != "off" ] && [ -x $GSTACK_ROOT/bin/gstack-telemetry-log ]; then
   $GSTACK_ROOT/bin/gstack-telemetry-log \
     --skill "SKILL_NAME" --duration "$_TEL_DUR" --outcome "OUTCOME" \
-    --used-browse "USED_BROWSE" --session-id "$_SESSION_ID" 2>/dev/null &
+    --used-browse "USED_BROWSE" --session-id "$_SESSION_ID" \
+    --error-message "ERROR_MESSAGE" --failed-step "FAILED_STEP" 2>/dev/null &
 fi
 ```
 
 Replace `SKILL_NAME`, `OUTCOME`, and `USED_BROWSE` before running.
+Replace `ERROR_MESSAGE` with a short description of the error (if outcome is error,
+otherwise use empty string ""), and `FAILED_STEP` with the step name or number where
+the failure occurred (if outcome is error, otherwise use empty string "").
 
 ## Plan Status Footer
 
diff --git a/test/helpers/carve-guards.ts b/test/helpers/carve-guards.ts
index 012b46c2a..490863cf5 100644
--- a/test/helpers/carve-guards.ts
+++ b/test/helpers/carve-guards.ts
@@ -194,10 +194,13 @@ export const CARVE_GUARDS: Record<string, CarveGuard> = {
     // always-loaded AskUserQuestion Format section.
     // v1.2.0 activation lift (shared first-run-guidance preamble) + #2077 ask-first scope gate.
     // +~1.3 KB: plan-mode auto-select-B scope-gate exceptions (2026-08).
-    maxSkeletonBytes: 89_000,
+    // +~340 B: telemetry --error-message/--failed-step flags + prose in the
+    // shared completion-status preamble (PR #769, 2026-08); this skill was the
+    // closest to its ceiling (landed 89040 / ratio 1.072).
+    maxSkeletonBytes: 89_400,
     minUnionBytes: 70_000,
     mustContain: ['design', 'visual'],
-    maxSizeRatio: 1.07,
+    maxSizeRatio: 1.08,
   },
   'plan-devex-review': {
     skill: 'plan-devex-review',