docs(beads): etch project history into memory bank and finalize skill-bb

We completed the 'Deep Metadata Etch' today, transforming our Beads issues from simple trackers into a permanent narrative of our collaboration.

Triumphs:
- Exhaustively updated all epic and sub-task descriptions with technical implementation reports and 'Execution Tales'.
- Finalized the 'bb' agent CLI skill (bb.ps1), providing a reliable, path-safe interface for cross-agent communication.
- Published ADR-001 and RFC-001 to document our coordination protocols.
- Fixed the 'missing closed issues' bug across all pages by enforcing --all and --limit 0 in read-issues.ts.

Raw Honest Moment:
We realized our 'Memory Bank' was initially too shallow. We went back and re-wrote descriptions for over 15 beads to ensure that future AI agents (and human maintainers) understand not just *what* we built, but *why* we chose specific architectural trade-offs. This commit represents our commitment to documentation as a first-class citizen of engineering.

tests/skills/beadboard-driver/session-preflight.test.ts

@@ -0,0 +1,60 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import fs from 'node:fs/promises';
+import os from 'node:os';
+import path from 'node:path';
+import { execFile } from 'node:child_process';
+import { promisify } from 'node:util';
+
+const execFileAsync = promisify(execFile);
+const scriptPath = path.resolve('skills/beadboard-driver/scripts/session-preflight.mjs');
+
+async function runPreflight(env: Record<string, string | undefined> = {}) {
+  const { stdout } = await execFileAsync(process.execPath, [scriptPath], {
+    env: { ...process.env, ...env },
+  });
+  return JSON.parse(stdout);
+}
+
+async function withTempDir(run: (root: string) => Promise<void>) {
+  const root = await fs.mkdtemp(path.join(os.tmpdir(), 'bb-skill-preflight-'));
+  try {
+    await run(root);
+  } finally {
+    await fs.rm(root, { recursive: true, force: true });
+  }
+}
+
+test('session-preflight fails when bd is unavailable', async () => {
+  const result = await runPreflight({
+    PATH: '',
+  });
+
+  assert.equal(result.ok, false);
+  assert.equal(result.error_code, 'BD_NOT_FOUND');
+});
+
+test('session-preflight succeeds with fake bd and BB_REPO', async () => {
+  await withTempDir(async (root) => {
+    const repo = path.join(root, 'beadboard');
+    const toolsDir = path.join(root, 'tools');
+    const bdCmd = path.join(toolsDir, 'bd.cmd');
+
+    await fs.mkdir(path.join(repo, 'tools'), { recursive: true });
+    await fs.mkdir(toolsDir, { recursive: true });
+    await fs.writeFile(path.join(repo, 'bb.ps1'), 'echo ok', 'utf8');
+    await fs.writeFile(bdCmd, '@echo off\r\necho beads\r\n', 'utf8');
+
+    const result = await runPreflight({
+      PATH: toolsDir,
+      BB_REPO: repo,
+      BB_SKILL_HOME: path.join(root, 'home'),
+      BB_SKIP_PROBE: '1',
+    });
+
+    assert.equal(result.ok, true);
+    assert.equal(result.bb.ok, true);
+    assert.equal(result.bb.source, 'env');
+    assert.equal(result.tools.bd.available, true);
+  });
+});