fix(memory-ingest): stop two silent transcript-ingest failures

Two independent bugs made transcript pages silently fail to reach the brain.

1. Frontmatter fence gluing. buildTranscriptPage() built the closing "---"
   with no trailing newline, and session bodies always start with "## ", so
   the rendered page ended "...---## User". gbrain's frontmatter matcher
   (/^---\r?\n([\s\S]*?)\r?\n---(\r?\n|$)/ in src/core/markdown.ts) requires
   the closing "---" to end its own line, so it skipped the glued fence,
   latched onto the next standalone "---" in the transcript body, parsed the
   prose between as YAML, and dropped the page with "Invalid YAML frontmatter".
   Transcripts with no later "---" fell back to body-only, silently losing
   their frontmatter. Fix: emit the fence on its own line with a blank
   separator, matching renderPageBody()'s artifact branch.

2. Slug collisions. Two source files can map to one path-derived slug (a
   session resumed under the same id on one day, or two ids sharing a 12-char
   prefix). writeStaged() names each file "${slug}.md", so the second
   overwrote the first; gbrain collected N-1 of N staged files and the
   reconciliation guard failed the whole batch every run. Fix:
   disambiguateSlugs() keeps the first occurrence and gives each later collider
   a stable "-<sha8(source_path)>" suffix (deterministic, and slug + page_slug
   move together so writeStaged, the failure mapping, and state recording agree).

Exports buildTranscriptPage, renderPageBody, and disambiguateSlugs for tests.
Adds regression tests for both failures.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Wave-amended: contributor's local-workaround docblock note removed; issue refs retargeted #2653 (closed by its author) -> #2724 (the live 887-staged-to-0-ingested report)

test/regression-transcript-frontmatter-fence.test.ts

@@ -0,0 +1,65 @@
+/**
+ * Regression: transcript frontmatter fence must terminate its own line.
+ *
+ * buildTranscriptPage() emitted a closing `---` with no trailing newline, and
+ * session bodies always start with "## ", so the rendered page ended
+ * `...---## User`. gbrain's frontmatter matcher
+ * (`/^---\r?\n([\s\S]*?)\r?\n---(\r?\n|$)/`, src/core/markdown.ts) requires the
+ * closing `---` to end its own line, so it skipped the glued fence, latched onto
+ * the next standalone `---` in the transcript body, parsed the prose between as
+ * YAML, and dropped the whole page with "Invalid YAML frontmatter". Transcripts
+ * with no later `---` fell back to body-only (frontmatter silently lost).
+ */
+import { describe, it, expect } from "bun:test";
+import { mkdtempSync, writeFileSync, rmSync } from "fs";
+import { tmpdir } from "os";
+import { join } from "path";
+import {
+  parseTranscriptJsonl,
+  buildTranscriptPage,
+  renderPageBody,
+} from "../bin/gstack-memory-ingest";
+
+// The exact fence matcher gbrain uses (src/core/markdown.ts). Kept here so the
+// test fails if the rendered fence ever regresses.
+const GBRAIN_FENCE_RE = /^---\r?\n([\s\S]*?)\r?\n---(\r?\n|$)/;
+
+describe("regression: transcript frontmatter fence terminates its own line", () => {
+  it("keeps a body-embedded `---` out of the frontmatter block", () => {
+    const dir = mkdtempSync(join(tmpdir(), "gstack-fence-"));
+    const file = join(dir, "sess.jsonl");
+    // User content carries a markdown horizontal rule (`---`) followed by a
+    // colon-bearing line — exactly what the old glued fence swept into YAML.
+    const content =
+      `{"type":"user","message":{"role":"user","content":"before rule\\n\\n---\\n\\nnot: valid: yaml: here"},` +
+      `"timestamp":"2026-05-01T00:00:00Z","cwd":"${dir}"}\n` +
+      `{"type":"assistant","message":{"role":"assistant","content":"ok"},"timestamp":"2026-05-01T00:00:01Z"}\n`;
+    writeFileSync(file, content, "utf-8");
+
+    const session = parseTranscriptJsonl(file);
+    expect(session).not.toBeNull();
+    const page = buildTranscriptPage(file, session!);
+    const staged = renderPageBody(page);
+
+    // The fence is never glued onto the body.
+    expect(staged).not.toContain("---##");
+
+    // gbrain's matcher closes the frontmatter at the real fence, not at the
+    // horizontal rule deep in the transcript body.
+    const m = staged.match(GBRAIN_FENCE_RE);
+    expect(m).not.toBeNull();
+    const frontmatter = m![1];
+    expect(frontmatter).toContain("session_id:");
+    expect(frontmatter).toContain("title:");
+    // The body (headings, the HR, the colon-trap line) must NOT bleed into YAML.
+    expect(frontmatter).not.toContain("## User");
+    expect(frontmatter).not.toContain("not: valid: yaml: here");
+
+    // And the parsed body (after the fence's trailing blank line) is the
+    // session content, not YAML-absorbed prose.
+    const body = staged.slice(m![0].length);
+    expect(body.trimStart().startsWith("## User")).toBe(true);
+
+    rmSync(dir, { recursive: true, force: true });
+  });
+});

test/regression-transcript-slug-collision.test.ts

@@ -0,0 +1,65 @@
+/**
+ * Regression: disambiguateSlugs resolves colliding staged slugs.
+ *
+ * Two source files can map to one path-derived transcript slug (a session
+ * resumed under the same id on one day, or two session ids sharing a 12-char
+ * prefix). writeStaged() names each file `${slug}.md`, so the second overwrote
+ * the first; gbrain then collected N-1 of N staged files and the
+ * staged-vs-collected reconciliation guard failed the whole batch every run
+ * ("accounted for N-1 of N staged ... Refusing to advance state").
+ */
+import { describe, it, expect } from "bun:test";
+import { disambiguateSlugs } from "../bin/gstack-memory-ingest";
+
+const mk = (slug: string, source_path: string) => ({
+  slug,
+  source_path,
+  rendered_body: "---\ntitle: x\n---\n\nbody",
+  page_slug: slug,
+  partial: false,
+  type: "transcript" as const,
+  git_remote: undefined,
+});
+
+describe("regression: disambiguateSlugs resolves colliding staged slugs", () => {
+  it("keeps the first occurrence and suffixes later colliders deterministically", () => {
+    const slug = "transcripts/claude-code/repo/2026-08-25-abc123def456";
+    const run = () => {
+      const pages = [mk(slug, "/a.jsonl"), mk(slug, "/b.jsonl")];
+      disambiguateSlugs(pages);
+      return pages;
+    };
+    const pages = run();
+    // First keeps the clean slug; second is disambiguated.
+    expect(pages[0].slug).toBe(slug);
+    expect(pages[1].slug).not.toBe(slug);
+    expect(pages[1].slug.startsWith(slug + "-")).toBe(true);
+    // slug and page_slug move together (downstream consumers must agree).
+    expect(pages[1].page_slug).toBe(pages[1].slug);
+    // Deterministic across runs (same source path → same suffix).
+    expect(run()[1].slug).toBe(pages[1].slug);
+  });
+
+  it("gives every member of a 3-way collision a distinct slug", () => {
+    const slug = "transcripts/codex/repo/2026-08-25-deadbeefcafe";
+    const pages = [
+      mk(slug, "/one.jsonl"),
+      mk(slug, "/two.jsonl"),
+      mk(slug, "/three.jsonl"),
+    ];
+    disambiguateSlugs(pages);
+    const slugs = new Set(pages.map((p) => p.slug));
+    expect(slugs.size).toBe(3);
+    expect(pages[0].slug).toBe(slug);
+  });
+
+  it("leaves non-colliding slugs untouched", () => {
+    const pages = [
+      mk("transcripts/a/repo/2026-08-25-1111", "/x.jsonl"),
+      mk("transcripts/b/repo/2026-08-25-2222", "/y.jsonl"),
+    ];
+    const before = pages.map((p) => p.slug);
+    disambiguateSlugs(pages);
+    expect(pages.map((p) => p.slug)).toEqual(before);
+  });
+});