fix(newos4): empty-pipeline crash, stacks in reports, frame in digest + dashboard (v4.6.55)

Root cause: splitPipe() splits on every '|', so `help |`, `| wc -l`, `a || b` produced a stage with
no argv and executePipeChain() called parts[0].toLowerCase() on undefined — 989 occurrences, first
filed 2026-10-20, unfixable from the report because bug reports dropped the stack that named
executePipeChain:3955. Same unguarded read existed in _classify().

- terminal.js: _classify() returns an inert classification for empty argv; executePipeChain()
  parses each stage once, filters stages with no argv (so the last real stage stays final), warns
  only when the whole pipeline is empty. Last-stage test now compares against the filtered length.
- module-system.js: `bug` diagnostics include the stack (10 frames, 1200 chars); auto-filed reports
  carry it too — they are the majority of the inbox and were previously message-only.
- report.php: per-stack 2 KB cap; fingerprint pinned to message/source/count so adding `stack`
  cannot break dedupe against reports filed before today.
- ingest.php: first_frame() parsed once on ingest, stored as `frame` on each signature.
- newos4-triage.py: FRAME| line with the first application frame.
- dashboard.php: frame under each Top Errors row.
- modules/test/test-pipe-guard.js: ordering tripwire (guard must precede the parts[0] read).

Verified: test RED exit=1 -> GREEN exit=0; browser matrix on v4.6.55 (help |, | wc -l,
echo hi || echo bye, ls | | wc -l, |) -> 0 new error signatures, "|" warns;
auto-filed report now carries stack (RPT-...f3e31124, archived after the probe);
frame = modules/core/core-bundle.js:3955:42; maintain OK; skill audit 7/7.

3 files changed, 44 insertions, 3 deletions

diff --git a/api/debug/dashboard.php b/api/debug/dashboard.php
index 08e6194..9b717c8 100644
--- a/api/debug/dashboard.php
+++ b/api/debug/dashboard.php
@@ -31,7 +31,8 @@ foreach ($errors as $e) {
     $hash = $e['hash'] ?? '';
     if ($hash) {
         if (!isset($topErrors[$hash])) {
-            $topErrors[$hash] = ['hash' => $hash, 'message' => $e['message'] ?? '', 'count' => 0, 'type' => $t];
+            $topErrors[$hash] = ['hash' => $hash, 'message' => $e['message'] ?? '', 'count' => 0, 'type' => $t,
+                                 'frame' => $e['frame'] ?? null];
         }
         $topErrors[$hash]['count'] += $e['count'] ?? 1;
     }
@@ -297,7 +298,9 @@ $thread = array_slice($thread, -6);
     <?php $i = 1; foreach ($topErrors as $e): ?>
       <tr>
       <td><?= $i++ ?></td>
-      <td class="max-w-300"><a href="error.php?hash=<?= urlencode($e['hash'] ?? '') ?>" style="color:var(--text);text-decoration:none;" title="View details"><?= htmlspecialchars(substr($e['message'] ?? '', 0, 80)) ?></a></td>
+      <td class="max-w-300"><a href="error.php?hash=<?= urlencode($e['hash'] ?? '') ?>" style="color:var(--text);text-decoration:none;" title="View details"><?= htmlspecialchars(substr($e['message'] ?? '', 0, 80)) ?></a>
+        <?php if (!empty($e['frame'])): ?><div class="hide-sm" style="font-size:.72em;color:var(--muted)"><?= htmlspecialchars($e['frame']) ?></div><?php endif; ?>
+      </td>
       <td class="hide-sm"><span class="tag"><?= htmlspecialchars($e['type'] ?? '?') ?></span></td>
       <td><?= (int)($e['count'] ?? 0) ?></td>
       </tr>
diff --git a/api/debug/ingest.php b/api/debug/ingest.php
index 7388bce..98354fe 100644
--- a/api/debug/ingest.php
+++ b/api/debug/ingest.php
@@ -80,6 +80,20 @@ function norm_ts($s, $fallback) {
     return gmdate('c', $t);   // always +00:00, never Z
 }
 
+// Where did it happen? Parsed ONCE here so the digest (Python) and the dashboard (PHP) read the
+// same value instead of re-implementing this regex twice. Returns 'modules/core/x.js:12:3'.
+function first_frame($stack) {
+    if (!is_string($stack) || $stack === '') return null;
+    foreach (preg_split('/\R/', $stack) as $i => $line) {
+        if ($i === 0 || !preg_match('/^\s+at /', $line)) continue;   // line 0 is "TypeError: ..."
+        if (preg_match('#([\w./-]+\.js)(?:\?v=[\w.]+)?:(\d+):(\d+)#', $line, $m)) {
+            $p = preg_replace('#^.*?/spaces/newos4/#', '', $m[1]);
+            return $p . ':' . $m[2] . ':' . $m[3];
+        }
+    }
+    return null;
+}
+
 $processed = 0;   // entries handled (NOT occurrences) — the client's truncation warning uses this
 foreach ($errors as $e) {
     $processed++;
@@ -103,6 +117,7 @@ foreach ($errors as $e) {
             $allErrors[$idx]['ingested_at'] = $now;
             if (!empty($e['stack'])) {
                 $allErrors[$idx]['stack'] = substr($e['stack'], 0, 2000);
+                $allErrors[$idx]['frame'] = first_frame($e['stack']) ?? ($allErrors[$idx]['frame'] ?? null);
             }
             $ingested += $delta;
         }
@@ -118,6 +133,7 @@ foreach ($errors as $e) {
         'source' => $e['source'] ?? '',
         'module' => $e['module'] ?? null,
         'stack' => isset($e['stack']) ? substr($e['stack'], 0, 2000) : null,
+        'frame' => first_frame($e['stack'] ?? null),
         'session_id' => $sessionId,
         'count' => $delta,
         'first_seen' => norm_ts($e['firstSeen'] ?? null, $now),
diff --git a/api/debug/report.php b/api/debug/report.php
index 5d4fc95..5625ffe 100644
--- a/api/debug/report.php
+++ b/api/debug/report.php
@@ -29,6 +29,18 @@ $body = (string)($payload['body'] ?? '');
 if (mb_strlen($body) > 4000) $body = mb_substr($body, 0, 4000);
 $diag = (isset($payload['diagnostics']) && is_array($payload['diagnostics'])) ? $payload['diagnostics'] : [];
 
+// Bound every stack: 20 errors x 10 frames of long URLs can otherwise approach the 512 KB ceiling
+// and reject a legitimate report.
+if (!empty($diag['errors']) && is_array($diag['errors'])) {
+    foreach ($diag['errors'] as $k => $de) {
+        if (!is_array($de)) { unset($diag['errors'][$k]); continue; }
+        if (isset($de['stack'])) {
+            $diag['errors'][$k]['stack'] = mb_substr((string)$de['stack'], 0, 2000);
+        }
+    }
+    $diag['errors'] = array_values($diag['errors']);
+}
+
 // Maintenance thread: lets the in-app agent and the Hermes maintenance job hold a conversation.
 // `thread` is a client-generated id (thr-xxxxxxxx); `kind` distinguishes agent feedback from
 // operator bug reports so triage can weight them differently.
@@ -62,7 +74,17 @@ foreach ($rate as $k => $v) {
 save_json(RATE_FILE, $rate);
 
 // Dedupe: same title + error set + version within 24h collapses onto the existing report.
-$fingerprint = sha1($title . '|' . json_encode($diag['errors'] ?? []) . '|' . (string)($diag['version'] ?? ''));
+// Hash only the fields the pre-2026-10-23 payload had. Adding `stack` to json_encode($diag['errors'])
+// would change every fingerprint, so an identical error filed today would not dedupe against the
+// same error filed yesterday.
+$errKey = [];
+foreach (is_array($diag['errors'] ?? null) ? $diag['errors'] : [] as $de) {
+    if (!is_array($de)) continue;
+    $errKey[] = ['message' => (string)($de['message'] ?? ''),
+                 'source'  => (string)($de['source'] ?? ''),
+                 'count'   => (int)($de['count'] ?? 1)];
+}
+$fingerprint = sha1($title . '|' . json_encode($errKey) . '|' . (string)($diag['version'] ?? ''));
 $existing = glob(REPORTS_DIR . '/RPT-*.json') ?: [];
 foreach (array_slice(array_reverse($existing), 0, 100) as $f) {
     $d = json_decode(@file_get_contents($f), true);