chore(memory): BDR-027 + LRN-038 + BLK-008 (install revert + Ubuntu 26.04 chromium)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UyNYwD4UccVw9ZCFZyJX55

.claude/memory/blockers.md

@@ -94,3 +94,11 @@ rules:
 - **Solution applied** (NOT full `./setup` — surgical, no side effects): (1) Linked `spec` only — `mkdir skills/spec` + `ln -snf <abs>/skills-external/gstack/spec/SKILL.md skills/spec/SKILL.md`, matching gstack setup:440-476 (per-skill real dir + SKILL.md symlink, name from frontmatter). (2) Added `spec` to `full.profile` + `web-full.profile` planning sections (must be in active profile `full` else `set full` re-disables it). (3) iOS 5 skills deliberately NOT linked — Linux host, device-farm needs Mac daemon + Tailscale + iOS devices = dead skills + token cost. (4) Completed `.gitignore` gstack allowlist: added all 12 missing (`spec`, 5 `ios-*`, 6 parked `document-generate/landing-report/scrape/setup-gbrain/skillify/sync-gbrain`), removed stale `checkpoint` (BLK-005 rename). Reason: `gstack on` (BDR-018) moves parked skills into `skills/` — any gstack skill missing from allowlist = untracked git noise on enable.
 - **Verified**: `profile show full`+`web-full` → spec enabled; allowlist drift recheck EMPTY; spec skill now visible to Claude.
 - **Status**: resolved. iOS = intentional exclusion (re-linkable via gstack `./setup` on a Mac). See [[gstack-gitignore-allowlist-completeness]] (LRN-025).
+
+## BLK-008 — gstack ./setup fails on Ubuntu 26.04 — Playwright chromium unsupported
+
+- **Date**: 2026-06-23
+- **Friction**: fresh Ubuntu 26.04, `make install` / `make plugin` → "Failed to install browsers / ERROR: Playwright does not support chromium on ubuntu26.04-x64" → "GStack ./setup failed". Non-fatal in our wrapper (warn only) but gstack's browser (`/browse`, `/qa`, design screenshots) is silently dead once gstack is enabled.
+- **Real cause**: Playwright 1.58.2 (pinned in the gstack submodule) registry lists `ubuntu20.04/22.04/24.04` only; 26.04 released later → not in list → `getHostPlatform` errors. Pure OS-newness, not an install bug.
+- **Solution**: gated `export PLAYWRIGHT_HOST_PLATFORM_OVERRIDE=ubuntu24.04-x64` (ubuntu >24.04 only) before gstack setup + persisted to `.bashrc` for runtime. Playwright then pulls a Chrome-for-Testing fallback build for ubuntu24.04. Verified on 26.04: `ldd` resolves all libs + real headless render OK.
+- **Status**: resolved (commit 211c7d4). Residual: exact rev 1208 launch not in-session-tested (sandbox download hung at extraction); proved via sibling rev 1228 same-platform CfT build. Confirm on next real `make plugin`. Proper upstream fix = gstack bumps Playwright to a version that lists ubuntu26.04. See [[LRN-038]].

.claude/memory/decisions.md

@@ -451,3 +451,14 @@ rules:
   - Secret in `repo/.env`, gitignored (status quo) — one `git add -f` or a `.gitignore` slip leaks it; the secret physically sits in the tree.
   - Scripts read `~/.claude/.env` directly — makes the symlink redundant but rewrites every read path and loses repo-local visibility.
 - **Reference**: `link.sh` `link_env()`, `.gitignore`, `lib/toggle-external.sh`, `install-plugins.sh`, `.env.example`, commits 131d0bc / f9cc866. Linked to [[BDR-025]] (magic's `MAGIC_API_KEY`, consumed by the gate's required-but-manual class).
+
+---
+
+## BDR-027 — Minimal npm-via-nvm bootstrap over centralized prereq lib (reverses the reverted approach)
+
+- **Date**: 2026-06-23
+- **Status**: accepted (supersedes the reverted `lib/install-prereqs.sh` centralization, commit 1ddeed1 removed from history)
+- **Decision**: the only real bootstrap blocker = `npm` absent on fresh machine. `install.sh` now installs current LTS via nvm (`v0.39.7` → `nvm install --lts`) ONLY when node/npm missing (`install_node_via_nvm`). Keep the inline per-tool prereq blocks in `install-plugins.sh` (no shared `ensure_*` lib). Re-add `jq` inline (Step 1) + `doctor.sh` fail-level — `jq` is an active-hook dep that was never installed.
+- **Why**: a 1-function fallback fixes the actual blocker. Folding 9 prereqs into a 245-line lib was scope-creep for "npm missing"; user reverted it. Inline blocks stay readable + co-located with their step.
+- **Alternatives rejected**: centralized `lib/install-prereqs.sh` (commit 1ddeed1 — over-engineered for the real blocker, reverted); leave `npm` as a hard `err` (the original bug — aborts before the CLI install).
+- **Reference**: `install.sh` `install_node_via_nvm`, `install-plugins.sh` Step 1 jq, `doctor.sh`, commits b6cc8b1 / 2194b11. Linked to [[BLK-008]] (the chromium half of the same fresh-Ubuntu-26.04 session).

.claude/memory/journal.md

@@ -172,3 +172,8 @@ rules:
 - Built via superpowers:writing-skills TDD: RED v1 baseline too easy (passed) → strengthened to RED v2 (pressured) which failed on anti-noise + invented subtask + no gate → GREEN passed. Gate STOP itself untested (non-interactive harness) — flagged as skill Red flag.
 - LRN-031: skill value = gate + anti-noise + determinism, NOT re-coding what a capable agent does free; if RED baseline passes, harden the fixture before writing.
 - Docs routing synced (CLAUDE.md table + README + USAGE) in separate commit; caveman-purge WIP in those files left unstaged. Commits 9dc2b83, be0f047, 765e9d7.
+
+## 2026-06-23
+
+- Reverted commit 1ddeed1 (centralized `lib/install-prereqs.sh`) — over-engineered for the real blocker. Replaced with minimal npm-via-nvm fallback in `install.sh` (b6cc8b1). Re-added `jq` prereq inline + `doctor.sh` fail-level (2194b11). BDR-027.
+- Diagnosed gstack chromium fail on Ubuntu 26.04: Playwright 1.58.2 doesn't list 26.04. Fix = gated `PLAYWRIGHT_HOST_PLATFORM_OVERRIDE=ubuntu24.04-x64`, wrapper-only (no submodule edit), install + runtime (211c7d4). Verified ldd + headless render on 26.04. BLK-008, LRN-038.

.claude/memory/learnings.md

@@ -519,3 +519,13 @@ rules:
 - **Pattern**: for the load-bearing scenario, run it on the REAL subject in the REAL invocation context (prod path `$HOME/.claude/lib/...`, prod-like PATH), not a stub or a "the code path is correct" argument. A stub proves branch coverage; only the real subject proves the integration. Always add a DISCRIMINATING case — force the failure state; the check must REPORT it, not pass by default (a check that only ever passes proves nothing).
 - **Future application**: any "fixed/works" claim on a critical path → produce the real run output (command + lines + exit code) before capitalizing or shipping; don't summarize ("condition met") in place of the output. Stub/logic = necessary for branch coverage, never sufficient for the integration claim. Most rentable discipline of the whole segment: every refutation came from execution, none from reasoning.
 - **Reference**: design-gate chantier, the `PATH=/usr/bin:/bin` matrix (magic-on → READY/0, magic-off → INCOMPLETE/10), commits 4d19135 / f963318. Linked to [[LRN-036]] (the concrete instance: the PATH cause surfaced only by the real run), [[LRN-034]] (its twin — 034 = don't trust a narrated *claim*; 037 = don't trust a *stub/logic argument* as proof; both demand execution against ground truth).
+
+---
+
+## LRN-038 — Playwright host-platform override for distros newer than its hardcoded support list
+
+- **Date**: 2026-06-23
+- **Context**: fresh Ubuntu 26.04. gstack `./setup` aborted: "Playwright does not support chromium on ubuntu26.04-x64". Playwright 1.58.2's registry hardcodes `ubuntu20.04/22.04/24.04` only; a newer release → no matching build → hard error. gstack is a pinned submodule (must not edit).
+- **Pattern**: `PLAYWRIGHT_HOST_PLATFORM_OVERRIDE=ubuntuXX.04-<arch>` forces a fallback build. MUST include arch (`x64`/`arm64`) — bare `ubuntu24.04` fails ("does not support … ubuntu24.04"). Set it from the WRAPPER: `export` before the submodule's setup (install-time download) AND persist to the shell profile (runtime launch) — both paths call `getHostPlatform`. No submodule edit. Gate on real OS version (`sort -V` compare) so supported distros are untouched. Test with the LOCAL `./node_modules/.bin/playwright` — `bunx playwright` pulls the LATEST playwright (different browser revision than the local import), which masks the result.
+- **Future application**: any pinned tool that hardcodes an OS allowlist breaks on a fresh OS upgrade. Look for a host-platform override env before bumping/forking the dep. Prove the fallback binary actually runs (`ldd` = no missing libs + a real headless render), not just that the download resolves.
+- **Reference**: `install-plugins.sh` `playwright_platform_override()`, commit 211c7d4. Linked to [[BLK-008]].