diff --git a/bin/gstack-community-dashboard b/bin/gstack-community-dashboard
index 135bd3e1..4b2e2b79 100755
--- a/bin/gstack-community-dashboard
+++ b/bin/gstack-community-dashboard
@@ -48,20 +48,15 @@ echo ""
 # ─── Weekly active installs ──────────────────────────────────
 WEEK_AGO="$(date -u -v-7d +%Y-%m-%dT%H:%M:%SZ 2>/dev/null || date -u -d '7 days ago' +%Y-%m-%dT%H:%M:%SZ 2>/dev/null || echo "")"
 if [ -n "$WEEK_AGO" ]; then
-  PULSE="$(curl -sf --max-time 10 \
-    "${SUPABASE_URL}/functions/v1/community-pulse" \
+  # Direct REST query (replaces unreliable community-pulse edge function)
+  WEEKLY="$(curl -sf --max-time 10 \
+    "${SUPABASE_URL}/rest/v1/update_checks?select=install_fingerprint&checked_at=gte.${WEEK_AGO}&source=eq.live" \
+    -H "apikey: ${ANON_KEY}" \
     -H "Authorization: Bearer ${ANON_KEY}" \
-    2>/dev/null || echo '{"weekly_active":0}')"
+    2>/dev/null | grep -o '"install_fingerprint":"[^"]*"' | sort -u | wc -l | tr -d ' ')"
+  WEEKLY="${WEEKLY:-0}"
 
-  WEEKLY="$(echo "$PULSE" | grep -o '"weekly_active":[0-9]*' | grep -o '[0-9]*' || echo "0")"
-  CHANGE="$(echo "$PULSE" | grep -o '"change_pct":[0-9-]*' | grep -o '[0-9-]*' || echo "0")"
-
-  echo "Weekly active installs: ${WEEKLY}"
-  if [ "$CHANGE" -gt 0 ] 2>/dev/null; then
-    echo "  Change: +${CHANGE}%"
-  elif [ "$CHANGE" -lt 0 ] 2>/dev/null; then
-    echo "  Change: ${CHANGE}%"
-  fi
+  echo "Weekly active installs: ${WEEKLY} unique"
   echo ""
 fi
 
@@ -70,7 +65,7 @@ echo "Top skills (last 7 days)"
 echo "────────────────────────"
 
 # Query telemetry_events, group by skill
-EVENTS="$(query "telemetry_events" "select=skill,gstack_version,session_id&event_type=eq.skill_run&event_timestamp=gte.${WEEK_AGO}&limit=1000" 2>/dev/null || echo "[]")"
+EVENTS="$(query "telemetry_events" "select=skill,gstack_version,session_id&event_type=eq.skill_run&event_timestamp=gte.${WEEK_AGO}&source=eq.live&limit=1000" 2>/dev/null || echo "[]")"
 
 if [ "$EVENTS" != "[]" ] && [ -n "$EVENTS" ]; then
   echo "$EVENTS" | grep -o '"skill":"[^"]*"' | awk -F'"' '{print $4}' | sort | uniq -c | sort -rn | head -10 | while read -r COUNT SKILL; do
@@ -85,7 +80,7 @@ echo ""
 echo "Top errors (last 7 days)"
 echo "────────────────────────"
 
-ERRORS="$(query "telemetry_events" "select=skill,error_class,error_message,failed_step,duration_s,session_id&outcome=eq.error&event_timestamp=gte.${WEEK_AGO}&order=event_timestamp.desc&limit=200" 2>/dev/null || echo "[]")"
+ERRORS="$(query "telemetry_events" "select=skill,error_class,error_message,failed_step,duration_s,session_id&outcome=eq.error&event_timestamp=gte.${WEEK_AGO}&source=eq.live&order=event_timestamp.desc&limit=200" 2>/dev/null || echo "[]")"
 
 if [ "$ERRORS" != "[]" ] && [ -n "$ERRORS" ]; then
   # Group by skill + error_class, show count and example message
diff --git a/bin/gstack-telemetry-log b/bin/gstack-telemetry-log
index 5edde6dd..1710256c 100755
--- a/bin/gstack-telemetry-log
+++ b/bin/gstack-telemetry-log
@@ -35,6 +35,7 @@ ERROR_CLASS=""
 ERROR_MESSAGE=""
 FAILED_STEP=""
 EVENT_TYPE="skill_run"
+SOURCE=""
 
 while [ $# -gt 0 ]; do
   case "$1" in
@@ -47,10 +48,14 @@ while [ $# -gt 0 ]; do
     --error-message) ERROR_MESSAGE="$2"; shift 2 ;;
     --failed-step)   FAILED_STEP="$2"; shift 2 ;;
     --event-type)    EVENT_TYPE="$2"; shift 2 ;;
+    --source)        SOURCE="$2"; shift 2 ;;
     *) shift ;;
   esac
 done
 
+# Source: flag > env > default 'live'
+SOURCE="${SOURCE:-${GSTACK_TELEMETRY_SOURCE:-live}}"
+
 # ─── Read telemetry tier ─────────────────────────────────────
 TIER="$("$CONFIG_CMD" get telemetry 2>/dev/null || true)"
 TIER="${TIER:-off}"
@@ -109,19 +114,19 @@ if [ -d "$STATE_DIR/sessions" ]; then
   [ -n "$_SC" ] && [ "$_SC" -gt 0 ] 2>/dev/null && SESSIONS="$_SC"
 fi
 
-# Generate installation_id for community tier
-INSTALL_ID=""
-if [ "$TIER" = "community" ]; then
-  HOST="$(hostname 2>/dev/null || echo "unknown")"
-  USER="$(whoami 2>/dev/null || echo "unknown")"
-  if command -v shasum >/dev/null 2>&1; then
-    INSTALL_ID="$(printf '%s-%s' "$HOST" "$USER" | shasum -a 256 | awk '{print $1}')"
-  elif command -v sha256sum >/dev/null 2>&1; then
-    INSTALL_ID="$(printf '%s-%s' "$HOST" "$USER" | sha256sum | awk '{print $1}')"
-  elif command -v openssl >/dev/null 2>&1; then
-    INSTALL_ID="$(printf '%s-%s' "$HOST" "$USER" | openssl dgst -sha256 | awk '{print $NF}')"
+# Generate/read persistent UUID fingerprint (all tiers, not just community)
+INSTALL_FP=""
+FP_FILE="$STATE_DIR/.install-id"
+if [ -f "$FP_FILE" ]; then
+  INSTALL_FP="$(cat "$FP_FILE" 2>/dev/null | tr -d '[:space:]')"
+fi
+if [ -z "$INSTALL_FP" ]; then
+  INSTALL_FP="$(uuidgen 2>/dev/null || cat /proc/sys/kernel/random/uuid 2>/dev/null || python3 -c 'import uuid; print(uuid.uuid4())' 2>/dev/null || echo "")"
+  INSTALL_FP="$(echo "$INSTALL_FP" | tr '[:upper:]' '[:lower:]')"  # normalize case
+  if [ -n "$INSTALL_FP" ]; then
+    mkdir -p "$STATE_DIR"
+    echo "$INSTALL_FP" > "$FP_FILE"
   fi
-  # If no SHA-256 command available, install_id stays empty
 fi
 
 # Local-only fields (never sent remotely)
@@ -145,20 +150,28 @@ ERR_MSG_FIELD="null"
 STEP_FIELD="null"
 [ -n "$FAILED_STEP" ] && STEP_FIELD="\"$(echo "$FAILED_STEP" | head -c 30)\""
 
+# Cap unreasonable durations
+if [ -n "$DURATION" ] && [ "$DURATION" -gt 86400 ] 2>/dev/null; then
+  DURATION=""  # null if > 24h
+fi
+if [ -n "$DURATION" ] && [ "$DURATION" -lt 0 ] 2>/dev/null; then
+  DURATION=""  # null if negative
+fi
+
 DUR_FIELD="null"
 [ -n "$DURATION" ] && DUR_FIELD="$DURATION"
 
 INSTALL_FIELD="null"
-[ -n "$INSTALL_ID" ] && INSTALL_FIELD="\"$INSTALL_ID\""
+[ -n "$INSTALL_FP" ] && INSTALL_FIELD="\"$INSTALL_FP\""
 
 BROWSE_BOOL="false"
 [ "$USED_BROWSE" = "true" ] && BROWSE_BOOL="true"
 
-printf '{"v":1,"ts":"%s","event_type":"%s","skill":"%s","session_id":"%s","gstack_version":"%s","os":"%s","arch":"%s","duration_s":%s,"outcome":"%s","error_class":%s,"error_message":%s,"failed_step":%s,"used_browse":%s,"sessions":%s,"installation_id":%s,"_repo_slug":"%s","_branch":"%s"}\n' \
+printf '{"v":1,"ts":"%s","event_type":"%s","skill":"%s","session_id":"%s","gstack_version":"%s","os":"%s","arch":"%s","duration_s":%s,"outcome":"%s","error_class":%s,"error_message":%s,"failed_step":%s,"used_browse":%s,"sessions":%s,"install_fingerprint":%s,"source":"%s","_repo_slug":"%s","_branch":"%s"}\n' \
   "$TS" "$EVENT_TYPE" "$SKILL" "$SESSION_ID" "$GSTACK_VERSION" "$OS" "$ARCH" \
   "$DUR_FIELD" "$OUTCOME" "$ERR_FIELD" "$ERR_MSG_FIELD" "$STEP_FIELD" \
   "$BROWSE_BOOL" "${SESSIONS:-1}" \
-  "$INSTALL_FIELD" "$REPO_SLUG" "$BRANCH" >> "$JSONL_FILE" 2>/dev/null || true
+  "$INSTALL_FIELD" "$SOURCE" "$REPO_SLUG" "$BRANCH" >> "$JSONL_FILE" 2>/dev/null || true
 
 # ─── Trigger sync if tier is not off ─────────────────────────
 SYNC_CMD="$GSTACK_DIR/bin/gstack-telemetry-sync"
diff --git a/bin/gstack-telemetry-sync b/bin/gstack-telemetry-sync
index d7ae2836..efb60c7f 100755
--- a/bin/gstack-telemetry-sync
+++ b/bin/gstack-telemetry-sync
@@ -76,19 +76,16 @@ while IFS= read -r LINE; do
   echo "$LINE" | grep -q '^{' || continue
 
   # Strip local-only fields + map JSONL field names to Postgres column names
+  # Backward compat: map old installation_id → install_fingerprint for unsent entries
   CLEAN="$(echo "$LINE" | sed \
     -e 's/,"_repo_slug":"[^"]*"//g' \
     -e 's/,"_branch":"[^"]*"//g' \
     -e 's/"v":/"schema_version":/g' \
     -e 's/"ts":/"event_timestamp":/g' \
     -e 's/"sessions":/"concurrent_sessions":/g' \
+    -e 's/"installation_id":/"install_fingerprint":/g' \
     -e 's/,"repo":"[^"]*"//g')"
 
-  # If anonymous tier, strip installation_id
-  if [ "$TIER" = "anonymous" ]; then
-    CLEAN="$(echo "$CLEAN" | sed 's/,"installation_id":"[^"]*"//g; s/,"installation_id":null//g')"
-  fi
-
   if [ "$FIRST" = "true" ]; then
     FIRST=false
   else
diff --git a/bin/gstack-update-check b/bin/gstack-update-check
index 8f5193be..56c0d370 100755
--- a/bin/gstack-update-check
+++ b/bin/gstack-update-check
@@ -167,9 +167,24 @@ if [ -z "${GSTACK_TELEMETRY_ENDPOINT:-}" ] && [ -f "$GSTACK_DIR/supabase/config.
 fi
 _SUPA_ENDPOINT="${GSTACK_TELEMETRY_ENDPOINT:-}"
 _SUPA_KEY="${GSTACK_SUPABASE_ANON_KEY:-}"
-# Respect telemetry opt-out — don't ping Supabase if user set telemetry: off
-_TEL_TIER="$("$GSTACK_DIR/bin/gstack-config" get telemetry 2>/dev/null || true)"
-if [ -n "$_SUPA_ENDPOINT" ] && [ -n "$_SUPA_KEY" ] && [ "${_TEL_TIER:-off}" != "off" ]; then
+# Generate/read install fingerprint (runs for ALL tiers including off)
+_FP=""
+_FP_FILE="$STATE_DIR/.install-id"
+if [ -f "$_FP_FILE" ]; then
+  _FP="$(cat "$_FP_FILE" 2>/dev/null | tr -d '[:space:]')"
+fi
+if [ -z "$_FP" ]; then
+  _FP="$(uuidgen 2>/dev/null || cat /proc/sys/kernel/random/uuid 2>/dev/null || python3 -c 'import uuid; print(uuid.uuid4())' 2>/dev/null || echo "")"
+  _FP="$(echo "$_FP" | tr '[:upper:]' '[:lower:]')"
+  if [ -n "$_FP" ]; then
+    mkdir -p "$STATE_DIR"
+    echo "$_FP" > "$_FP_FILE"
+  fi
+fi
+# Update-check pings always fire (ungated from telemetry tier).
+# This sends only: version, OS, and a random UUID. No usage data.
+# Equivalent to what GitHub sees in HTTP access logs for VERSION.
+if [ -n "$_SUPA_ENDPOINT" ] && [ -n "$_SUPA_KEY" ]; then
   _OS="$(uname -s | tr '[:upper:]' '[:lower:]')"
   curl -sf --max-time 5 \
     -X POST "${_SUPA_ENDPOINT}/update_checks" \
@@ -177,7 +192,7 @@ if [ -n "$_SUPA_ENDPOINT" ] && [ -n "$_SUPA_KEY" ] && [ "${_TEL_TIER:-off}" != "
     -H "apikey: ${_SUPA_KEY}" \
     -H "Authorization: Bearer ${_SUPA_KEY}" \
     -H "Prefer: return=minimal" \
-    -d "{\"gstack_version\":\"$LOCAL\",\"os\":\"$_OS\"}" \
+    -d "{\"gstack_version\":\"$LOCAL\",\"os\":\"$_OS\",\"install_fingerprint\":\"${_FP}\"}" \
     >/dev/null 2>&1 &
 fi
 
diff --git a/scripts/gen-skill-docs.ts b/scripts/gen-skill-docs.ts
index ae38c2d1..08b64aa5 100644
--- a/scripts/gen-skill-docs.ts
+++ b/scripts/gen-skill-docs.ts
@@ -209,8 +209,12 @@ _TEL=$(${ctx.paths.binDir}/gstack-config get telemetry 2>/dev/null || true)
 _TEL_PROMPTED=$([ -f ~/.gstack/.telemetry-prompted ] && echo "yes" || echo "no")
 _TEL_START=$(date +%s)
 _SESSION_ID="$$-$(date +%s)"
+echo $_TEL_START > ~/.gstack/analytics/.tel-start-$PPID
+echo $_SESSION_ID > ~/.gstack/analytics/.tel-session-$PPID
 echo "TELEMETRY: \${_TEL:-off}"
 echo "TEL_PROMPTED: $_TEL_PROMPTED"
+echo "TEL_START: $_TEL_START"
+echo "SESSION_ID: $_SESSION_ID"
 _EMAIL=$(${ctx.paths.binDir}/gstack-config get email 2>/dev/null || true)
 _COMM_PROMPTED=$([ -f ~/.gstack/.community-prompted ] && echo "yes" || echo "no")
 _AUTH_OK=$(${ctx.paths.binDir}/gstack-auth-refresh --check 2>/dev/null && echo "yes" || echo "no")
@@ -526,7 +530,7 @@ Hey gstack team — ran into this while using /{skill-name}:
 Slug: lowercase, hyphens, max 60 chars (e.g. \`browse-js-no-await\`). Skip if file already exists. Max 3 reports per session. File inline and continue — don't stop the workflow. Tell user: "Filed gstack field report: {title}"`;
 }
 
-function generateCompletionStatus(): string {
+function generateCompletionStatus(ctx: TemplateContext): string {
   return `## Completion Status Protocol
 
 When completing a skill workflow, report status using one of:
@@ -577,11 +581,15 @@ Skipping this command loses session duration and outcome data.
 Run this bash:
 
 \`\`\`bash
+_TEL_START=$(cat ~/.gstack/analytics/.tel-start-$PPID 2>/dev/null || echo 0)
+_SESSION_ID=$(cat ~/.gstack/analytics/.tel-session-$PPID 2>/dev/null || echo "")
 _TEL_END=$(date +%s)
 _TEL_DUR=$(( _TEL_END - _TEL_START ))
+rm -f ~/.gstack/analytics/.tel-start-$PPID ~/.gstack/analytics/.tel-session-$PPID 2>/dev/null || true
 rm -f ~/.gstack/analytics/.pending-"$_SESSION_ID" 2>/dev/null || true
-~/.claude/skills/gstack/bin/gstack-telemetry-log \\
+${ctx.paths.binDir}/gstack-telemetry-log \\
   --skill "SKILL_NAME" --duration "$_TEL_DUR" --outcome "OUTCOME" \\
+  --source "\${GSTACK_TELEMETRY_SOURCE:-live}" \\
   --used-browse "USED_BROWSE" --session-id "$_SESSION_ID" \\
   --error-class "ERROR_CLASS" --error-message "ERROR_MESSAGE" \\
   --failed-step "FAILED_STEP" 2>/dev/null &
@@ -603,7 +611,7 @@ When you are in plan mode and about to call ExitPlanMode:
 3. If it does NOT — run this command:
 
 \\\`\\\`\\\`bash
-~/.claude/skills/gstack/bin/gstack-review-read
+${ctx.paths.binDir}/gstack-review-read
 \\\`\\\`\\\`
 
 Then write a \`## GSTACK REVIEW REPORT\` section to the end of the plan file:
@@ -643,7 +651,7 @@ function generatePreamble(ctx: TemplateContext): string {
     generateRepoModeSection(),
     generateSearchBeforeBuildingSection(ctx),
     generateContributorMode(),
-    generateCompletionStatus(),
+    generateCompletionStatus(ctx),
   ].join('\n\n');
 }
 
diff --git a/supabase/migrations/003_source_and_guards.sql b/supabase/migrations/003_source_and_guards.sql
new file mode 100644
index 00000000..06bdbdf6
--- /dev/null
+++ b/supabase/migrations/003_source_and_guards.sql
@@ -0,0 +1,129 @@
+-- gstack telemetry data integrity + growth metrics
+-- Adds source tagging, install fingerprinting, duration guards, and growth views.
+--
+-- PREREQUISITE: Run Phase 4A cleanup BEFORE this migration:
+--   UPDATE telemetry_events SET duration_s = NULL WHERE duration_s > 86400 OR duration_s < 0;
+
+-- ─── Source field (live/test/dev tagging) ─────────────────────
+ALTER TABLE telemetry_events ADD COLUMN source TEXT DEFAULT 'live';
+ALTER TABLE update_checks ADD COLUMN source TEXT DEFAULT 'live';
+
+-- ─── Install fingerprinting (expand-then-contract) ───────────
+-- ADD new column (don't RENAME — old clients still POST installation_id)
+ALTER TABLE telemetry_events ADD COLUMN install_fingerprint TEXT;
+ALTER TABLE update_checks ADD COLUMN install_fingerprint TEXT;
+
+-- Trigger: copy installation_id → install_fingerprint on INSERT (backward compat)
+CREATE OR REPLACE FUNCTION copy_install_id_to_fingerprint()
+RETURNS TRIGGER AS $$
+BEGIN
+  IF NEW.install_fingerprint IS NULL AND NEW.installation_id IS NOT NULL THEN
+    NEW.install_fingerprint := NEW.installation_id;
+  END IF;
+  RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER trg_copy_install_fingerprint
+  BEFORE INSERT ON telemetry_events
+  FOR EACH ROW
+  EXECUTE FUNCTION copy_install_id_to_fingerprint();
+
+-- Backfill existing rows
+UPDATE telemetry_events
+  SET install_fingerprint = installation_id
+  WHERE installation_id IS NOT NULL AND install_fingerprint IS NULL;
+
+-- ─── Duration guard ──────────────────────────────────────────
+ALTER TABLE telemetry_events
+  ADD CONSTRAINT duration_reasonable
+  CHECK (duration_s IS NULL OR (duration_s >= 0 AND duration_s <= 86400));
+
+-- ─── Indexes for fingerprint joins + source filtering ────────
+CREATE INDEX idx_update_checks_fingerprint ON update_checks (install_fingerprint);
+CREATE INDEX idx_telemetry_fingerprint ON telemetry_events (install_fingerprint);
+CREATE INDEX idx_update_checks_source ON update_checks (source) WHERE source = 'live';
+CREATE INDEX idx_telemetry_source ON telemetry_events (source) WHERE source = 'live';
+
+-- ─── Recreate crash_clusters with source filter ──────────────
+DROP VIEW IF EXISTS crash_clusters;
+CREATE VIEW crash_clusters AS
+SELECT
+  error_class,
+  gstack_version,
+  COUNT(*) as total_occurrences,
+  COUNT(DISTINCT install_fingerprint) as identified_users,
+  COUNT(*) - COUNT(install_fingerprint) as anonymous_occurrences,
+  MIN(event_timestamp) as first_seen,
+  MAX(event_timestamp) as last_seen
+FROM telemetry_events
+WHERE outcome = 'error' AND error_class IS NOT NULL
+  AND (source = 'live' OR source IS NULL)
+GROUP BY error_class, gstack_version
+ORDER BY total_occurrences DESC;
+
+-- ─── Recreate skill_sequences with source filter ─────────────
+DROP VIEW IF EXISTS skill_sequences;
+CREATE VIEW skill_sequences AS
+SELECT
+  a.skill as skill_a,
+  b.skill as skill_b,
+  COUNT(DISTINCT a.session_id) as co_occurrences
+FROM telemetry_events a
+JOIN telemetry_events b ON a.session_id = b.session_id
+  AND a.skill != b.skill
+  AND a.event_timestamp < b.event_timestamp
+WHERE a.event_type = 'skill_run' AND b.event_type = 'skill_run'
+  AND (a.source = 'live' OR a.source IS NULL)
+  AND (b.source = 'live' OR b.source IS NULL)
+GROUP BY a.skill, b.skill
+HAVING COUNT(DISTINCT a.session_id) >= 10
+ORDER BY co_occurrences DESC;
+
+-- ─── Growth views ────────────────────────────────────────────
+
+-- Daily active installs (materialized for dashboard perf)
+CREATE MATERIALIZED VIEW daily_active_installs AS
+SELECT DATE(checked_at) as day,
+       COUNT(DISTINCT install_fingerprint) as unique_installs,
+       COUNT(*) as total_pings
+FROM update_checks
+WHERE source = 'live' OR source IS NULL
+GROUP BY DATE(checked_at)
+ORDER BY day DESC;
+
+-- Version adoption velocity (materialized)
+CREATE MATERIALIZED VIEW version_adoption AS
+SELECT DATE(checked_at) as day,
+       gstack_version,
+       COUNT(DISTINCT install_fingerprint) as unique_installs
+FROM update_checks
+WHERE source = 'live' OR source IS NULL
+GROUP BY DATE(checked_at), gstack_version
+ORDER BY day DESC;
+
+-- Growth funnel: first-seen based (not heartbeat-based)
+CREATE VIEW growth_funnel AS
+WITH first_seen AS (
+  SELECT install_fingerprint, MIN(checked_at) as first_check
+  FROM update_checks
+  WHERE install_fingerprint IS NOT NULL AND (source = 'live' OR source IS NULL)
+  GROUP BY install_fingerprint
+)
+SELECT
+  DATE(fs.first_check) as install_day,
+  COUNT(DISTINCT fs.install_fingerprint) as installs,
+  COUNT(DISTINCT CASE WHEN te.event_timestamp IS NOT NULL THEN fs.install_fingerprint END) as activated,
+  COUNT(DISTINCT CASE WHEN uc2.checked_at IS NOT NULL THEN fs.install_fingerprint END) as retained_7d
+FROM first_seen fs
+LEFT JOIN telemetry_events te
+  ON fs.install_fingerprint = te.install_fingerprint
+  AND te.event_timestamp BETWEEN fs.first_check AND fs.first_check + INTERVAL '24 hours'
+  AND te.event_type = 'skill_run'
+  AND (te.source = 'live' OR te.source IS NULL)
+LEFT JOIN update_checks uc2
+  ON fs.install_fingerprint = uc2.install_fingerprint
+  AND uc2.checked_at BETWEEN fs.first_check + INTERVAL '7 days' AND fs.first_check + INTERVAL '14 days'
+WHERE fs.install_fingerprint IS NOT NULL
+GROUP BY DATE(fs.first_check)
+ORDER BY install_day DESC;
diff --git a/test/helpers/session-runner.ts b/test/helpers/session-runner.ts
index 5e0b057a..0bf3b489 100644
--- a/test/helpers/session-runner.ts
+++ b/test/helpers/session-runner.ts
@@ -176,7 +176,7 @@ export async function runSkillTest(options: {
     cwd: workingDirectory,
     stdout: 'pipe',
     stderr: 'pipe',
-    env: { ...process.env, GSTACK_STATE_DIR: testStateDir },
+    env: { ...process.env, GSTACK_STATE_DIR: testStateDir, GSTACK_TELEMETRY_SOURCE: 'test' },
   });
 
   // Race against timeout
diff --git a/test/telemetry.test.ts b/test/telemetry.test.ts
index 4dc79b29..79905745 100644
--- a/test/telemetry.test.ts
+++ b/test/telemetry.test.ts
@@ -72,33 +72,95 @@ describe('gstack-telemetry-log', () => {
     expect(readJsonl()).toHaveLength(0);
   });
 
-  test('includes installation_id for community tier', () => {
+  test('includes install_fingerprint for community tier (UUID)', () => {
     setConfig('telemetry', 'community');
     run(`${BIN}/gstack-telemetry-log --skill review --duration 100 --outcome success --session-id comm-123`);
 
     const events = parseJsonl();
     expect(events).toHaveLength(1);
-    // installation_id should be a SHA-256 hash (64 hex chars)
-    expect(events[0].installation_id).toMatch(/^[a-f0-9]{64}$/);
+    // install_fingerprint should be a UUID (lowercase)
+    expect(events[0].install_fingerprint).toMatch(/^[a-f0-9-]{36}$/);
   });
 
-  test('installation_id is null for anonymous tier', () => {
+  test('includes install_fingerprint for anonymous tier (not null — UUID is not PII)', () => {
     setConfig('telemetry', 'anonymous');
     run(`${BIN}/gstack-telemetry-log --skill qa --duration 50 --outcome success --session-id anon-123`);
 
     const events = parseJsonl();
-    expect(events[0].installation_id).toBeNull();
+    // All tiers now get install_fingerprint (random UUID, not PII)
+    expect(events[0].install_fingerprint).toMatch(/^[a-f0-9-]{36}$/);
   });
 
-  test('includes error_class when provided', () => {
+  test('source field defaults to live', () => {
     setConfig('telemetry', 'anonymous');
-    run(`${BIN}/gstack-telemetry-log --skill browse --duration 10 --outcome error --error-class timeout --session-id err-123`);
+    run(`${BIN}/gstack-telemetry-log --skill qa --duration 50 --outcome success --session-id src-123`);
+
+    const events = parseJsonl();
+    expect(events[0].source).toBe('live');
+  });
+
+  test('--source flag overrides default', () => {
+    setConfig('telemetry', 'anonymous');
+    run(`${BIN}/gstack-telemetry-log --skill qa --duration 50 --outcome success --source test --session-id src-456`);
+
+    const events = parseJsonl();
+    expect(events[0].source).toBe('test');
+  });
+
+  test('GSTACK_TELEMETRY_SOURCE env sets source', () => {
+    setConfig('telemetry', 'anonymous');
+    run(`GSTACK_TELEMETRY_SOURCE=test ${BIN}/gstack-telemetry-log --skill qa --duration 50 --outcome success --session-id src-789`);
+
+    const events = parseJsonl();
+    expect(events[0].source).toBe('test');
+  });
+
+  test('duration > 86400 is capped to null', () => {
+    setConfig('telemetry', 'anonymous');
+    run(`${BIN}/gstack-telemetry-log --skill qa --duration 100000 --outcome success --session-id dur-123`);
+
+    const events = parseJsonl();
+    expect(events[0].duration_s).toBeNull();
+  });
+
+  test('negative duration is capped to null', () => {
+    setConfig('telemetry', 'anonymous');
+    run(`${BIN}/gstack-telemetry-log --skill qa --duration -5 --outcome success --session-id dur-456`);
+
+    const events = parseJsonl();
+    expect(events[0].duration_s).toBeNull();
+  });
+
+  test('install_fingerprint persists across runs', () => {
+    setConfig('telemetry', 'anonymous');
+    run(`${BIN}/gstack-telemetry-log --skill qa --duration 10 --outcome success --session-id fp-1`);
+    run(`${BIN}/gstack-telemetry-log --skill qa --duration 20 --outcome success --session-id fp-2`);
+
+    const events = parseJsonl();
+    expect(events).toHaveLength(2);
+    expect(events[0].install_fingerprint).toBe(events[1].install_fingerprint);
+  });
+
+  test('includes error_class, error_message, and failed_step when provided', () => {
+    setConfig('telemetry', 'anonymous');
+    run(`${BIN}/gstack-telemetry-log --skill browse --duration 10 --outcome error --error-class timeout --error-message "request timed out after 30s" --failed-step "goto_page" --session-id err-123`);
 
     const events = parseJsonl();
     expect(events[0].error_class).toBe('timeout');
+    expect(events[0].error_message).toBe('request timed out after 30s');
+    expect(events[0].failed_step).toBe('goto_page');
     expect(events[0].outcome).toBe('error');
   });
 
+  test('truncates long error messages', () => {
+    setConfig('telemetry', 'anonymous');
+    const longMsg = 'a'.repeat(300);
+    run(`${BIN}/gstack-telemetry-log --skill qa --outcome error --error-message "${longMsg}" --session-id trunc-123`);
+
+    const events = parseJsonl();
+    expect(events[0].error_message).toHaveLength(200);
+  });
+
   test('handles missing duration gracefully', () => {
     setConfig('telemetry', 'anonymous');
     run(`${BIN}/gstack-telemetry-log --skill qa --outcome success --session-id nodur-123`);