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.

1 files changed, 29 insertions, 7 deletions

diff --git a/modules/core/terminal.js b/modules/core/terminal.js
index c586538..ad4b105 100644
--- a/modules/core/terminal.js
+++ b/modules/core/terminal.js
@@ -157,7 +157,14 @@
                 return args;
             }
             _classify(raw) {
-                const parts = this._parseArgs(raw.trim());
+                const parts = this._parseArgs(String(raw || '').trim());
+                // `help |` and `| wc -l` produce an empty pipeline stage; parts[0] was undefined
+                // and every such invocation threw TypeError from this line (989 occurrences,
+                // first filed 2026-10-20). Classify the empty command as inert instead.
+                if (!parts.length) {
+                    return { cmd: '', args: [], known: true, destructive: false, system: false,
+                             unknown: false, hasSuspicious: false };
+                }
                 const cmd = parts[0].toLowerCase();
                 const args = parts.slice(1);
                 // Internal commands always allowed at terminal level, but security still classifies
@@ -1532,12 +1539,27 @@
                 return parts;
             }
             async executePipeChain(pipeParts) {
+                // Parse every stage once, then drop the ones with no argv. `help |` splits to
+                // ['help',''], `help | ""` to ['help',''] and `| wc -l` to ['','wc -l'] — all three
+                // produced an empty argv whose parts[0] was undefined and threw TypeError from
+                // parts[0].toLowerCase() (989 occurrences, first filed 2026-10-20). Filtering on
+                // argv (not just the string) also keeps the LAST real stage final, so its output is
+                // never swallowed by a trailing empty segment.
+                const stages = pipeParts
+                    .map(t => this.security._parseArgs(String(t || '').trim()))
+                    .filter(argv => argv.length > 0);
+                if (!stages.length) {
+                    this.print('⚠️ Empty pipeline — nothing to run', 'warning');
+                    return;
+                }
                 let pipeInput = null;
-                for (let i = 0; i < pipeParts.length; i++) {
-                    const cmdText = pipeParts[i];
-                    const parts = this.security._parseArgs(cmdText);
-                    const cmd = parts[0].toLowerCase();
-                    const args = parts.slice(1);
+                for (let i = 0; i < stages.length; i++) {
+                    const argv = stages[i];
+                    const cmd = argv[0].toLowerCase();
+                    const args = argv.slice(1);
+                    // Rebuilt from argv so the security classifier sees the same tokenisation the
+                    // dispatcher will use (quotes already stripped by _parseArgs).
+                    const cmdText = argv.join(' ');
                     // v4.5.67: Security gate for pipe stages — was completely bypassed
                     const cls = this.security._classify(cmdText);
                     if (cls.destructive && this.security.level > 0) {
@@ -1553,7 +1575,7 @@
                         return;
                     }
                     this._pipeInput = pipeInput;
-                    if (i < pipeParts.length - 1) {
+                    if (i < stages.length - 1) {
                         pipeInput = await this.capturePipeOutput(cmd, args);
                     } else {
                         await this.dispatchCommand(cmd, args);