Merge origin/main (v1.80.0.0) into consolidate-browser-skills-into-aside; queue-advance release to v1.81.0.0

Both sides claimed v1.80.0.0, so VERSION, package.json and the agents digest
auto-merged without a conflict; the release is re-versioned to the next free
MINOR slot (bin/gstack-next-version), the size-budget baseline renamed to
match, and the CHANGELOG carries the Aside-first entry above main's.

Two semantic conflicts hidden in the clean setup auto-merge are resolved here:
- _prune_stale_generated deleted a REAL host directory on banner-only proof;
  main's #2119 gate makes that weak proof file-scoped, so real dirs now go
  through _cleanup_weak_dir (SKILL.md, marker and our links only).
- _browser_hint and the Chromium bootstrap summary now consult _PW_FAIL_REASON
  and Aside presence, so they never promise a bundled browser that cannot
  launch and never tell an Aside user their browser skills are gone.
README, TESTING_INTERNALS and TODOS wording reconciled with the merged tree.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

test/helpers/bash-script.ts

@@ -0,0 +1,60 @@
+/**
+ * Run an assembled bash script from a TEMP FILE — never via `bash -c <argv>`.
+ *
+ * Why: the setup harnesses slice functions out of `setup` and join them into
+ * one script. On Windows, bash is an MSYS2 program; when its parent is a
+ * non-MSYS process (bun), msys-2.0.dll's build_argv() runs every argument
+ * containing any of `?*["'(){}` through globify()/glob(). glob() copies the
+ * pattern into a fixed `Char patbuf[8192]` and silently stops after
+ * 8192 - MB_CUR_MAX (8186 characters under C.UTF-8); GLOB_NOCHECK then hands
+ * the truncated text to bash as the argument. Observed on windows-free-tests
+ * when the alias harness grew from 6.7 KB to 15.7 KB: the `-c` script was cut
+ * inside a single-quoted token on line 178 ("unexpected EOF while looking for
+ * matching `'"). A short, glob-character-free file path never enters
+ * globify, and bash reads the file's bytes directly, so quoting and encoding
+ * are never re-parsed by any argument layer. The same ~8186-char ceiling
+ * applies to any MSYS tool (sh, sed, awk, grep) spawned from bun on Windows
+ * with a long single argument.
+ *
+ * `timeout` is always set (test/spawnsync-timeout-tripwire.test.ts).
+ */
+import { spawnSync } from 'child_process';
+import * as fs from 'fs';
+import * as os from 'os';
+import * as path from 'path';
+
+export interface BashScriptResult {
+  status: number;
+  stdout: string;
+  stderr: string;
+  signal: NodeJS.Signals | null;
+}
+
+export interface BashScriptOptions {
+  timeout?: number;
+  env?: NodeJS.ProcessEnv;
+  cwd?: string;
+}
+
+export function runBashScript(script: string, opts: BashScriptOptions = {}): BashScriptResult {
+  const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'gstack-bash-script-'));
+  const file = path.join(dir, 'script.sh');
+  // LF only: a stray CR would reach bash as part of a token.
+  fs.writeFileSync(file, script.replace(/\r\n/g, '\n'));
+  try {
+    const r = spawnSync('bash', [file], {
+      encoding: 'utf-8',
+      timeout: opts.timeout ?? 60_000,
+      ...(opts.env ? { env: opts.env } : {}),
+      ...(opts.cwd ? { cwd: opts.cwd } : {}),
+    });
+    // A spawn failure (bash missing) or a timeout kill has no bash stderr of
+    // its own; surface the cause instead of a bare status -1.
+    const stderr = (r.stderr ?? '') + (r.error ? `\n[spawn] ${r.error.message}` : '');
+    return { status: r.status ?? -1, stdout: r.stdout ?? '', stderr, signal: r.signal ?? null };
+  } finally {
+    // Best-effort: an AV scanner or indexer still holding script.sh on
+    // Windows must never turn a good result into an unlink error.
+    try { fs.rmSync(dir, { recursive: true, force: true }); } catch { /* best-effort temp cleanup */ }
+  }
+}

test/helpers/carve-guards.ts

@@ -478,7 +478,7 @@ export const CARVE_GUARDS: Record<string, CarveGuard> = {
     },
     behavioral: 'prompt',
     maxSkeletonBytes: 74_500, // + Aside browser contract for Step 7 canary ({{ASIDE_SETUP}}); measured 73_523
-    maxSizeRatio: 1.10, // + v1.80 Aside contract + gstack-browser fallback block; measured 1.077
+    maxSizeRatio: 1.10, // + v1.81 Aside contract + gstack-browser fallback block; measured 1.077
     minUnionBytes: 91_000, // Phase 4 wave 1; estimated union ~94.9KB
     mustContain: ['readiness', 'merge', 'canary', 'revert', 'staging'],
   },
@@ -607,7 +607,7 @@ export const CARVE_GUARDS: Record<string, CarveGuard> = {
     },
     behavioral: 'prompt',
     maxSkeletonBytes: 63_500, // + v2.0 {{ASIDE_SETUP}}/{{BROWSE_FALLBACK}} (replaces the browse setup block); measured 61_253
-    maxSizeRatio: 1.08, // + v1.80 Aside contract + gstack-browser fallback block; measured 1.063
+    maxSizeRatio: 1.08, // + v1.81 Aside contract + gstack-browser fallback block; measured 1.063
     minUnionBytes: 69_500, // measured union 70,385
     // 'aside repl' pins the Aside contract; '$B goto' pins the fallback block in the always-loaded skeleton.
     mustContain: ['bug', 'aside repl', '$B goto', 'fix', 'Health Score Rubric', 'regression'],