feat(profile): set symmetric on managed externals + MCPs (BDR-079)

- MANAGED_EXTERNALS (emil-design-eng, frontend-design,
  design-motion-principles, impeccable) + MANAGED_MCPS (magic):
  cmd_set now trims both when the profile does not list them —
  design leftovers no longer survive a 'set backend'
- cmd_set refactored to 4 symmetric trim helpers; nothing outside
  the MANAGED_* allowlists is ever auto-toggled (darwin-skill manual)
- enable_skill external: from-source fallback (ln -sf
  skills-external/<name>), mirrors toggle-external.sh
- stale usage() NOTE + SKILL.md updated to the both-ways reality
- hermetic test: 16 checks, fixture repo + fake claude shim (gstack
  on-demand, from-source, park/restore, magic add/remove, non-managed
  untouched); shellcheck + full make test green

.claude/memory/decisions.md

@@ -1065,3 +1065,6 @@ Supersedes BDR-076 scope + amends BDR-066. Doctrine: session model (Fable) = mai
 ### BDR-078 — ctx7 coverage: central fast-libs list + once-per-session reminder hook; every code path covered [accepted] (2026-07-20)
 Refines BDR-053 (single surface). Audit 2026-07-20: coverage PARTIAL — find-docs fired on user doc-questions only; ship-feature 0c / init-project 5c pre-fetched; /feat //bugfix executors + ad-hoc coding NEVER consulted ctx7; fast-libs list hardcoded 3× (drift risk). 4 closures shipped: (a) find-docs description += BEFORE-writing-code trigger (fast-moving lib, even without doc question, unless fresh cache) + cache-first rule in body (tee fetched docs to .ctx7-cache/); (b) feater+bugfixer briefs += fast-lib docs rule — read fresh `.ctx7-cache/<lib>*.md`, else `npx ctx7@latest` fetch max 2 topics, else `ctx7 cache miss: <lib>` in NOTES + proceed (executors lack Skill tool → Bash path); (c) hooks/ctx7-reminder.sh UserPromptSubmit — ONE fire/session (sentinel on session_id), only when project manifest carries fast-libs; reports cache state; skips <task-notification> turns; always exit 0; (d) lib/fast-libs.sh = SINGLE SOURCE (detect / cache-status verbs, JS package.json anchored full-key match + Python requirements/pyproject, 7-day freshness, LC_ALL=C sort locale-independent) consumed by hook + 3 pipeline skills + 2 briefs. 2nd session surface DELIBERATE, not a BDR-053 reversal: 053 killed a 490-tok ALWAYS-ON rule duplicate; hook costs ~0 quiet, 1 line once when fast-libs present. Alternatives rejected: PreToolUse Edit/Write gate (fires per-edit = noise); description-only fix (probabilistic, executors unreachable). Tests: lib/tests/fast-libs.test.sh 11 checks (anchored/near-miss/py/none, cache fresh/stale/missing, hook fire/sentinel/quiet×2); shellcheck + full make test green. Branch feature/ctx7-coverage, unmerged (human gate).
 Amendment (same session): skills/find-docs = machine-owned dist (gitignored, ctx7 regenerates on fresh clone) → durable copy of closure (a) lives in install-plugins.sh STEP ctx7 (idempotent grep-guarded python patch, fixture-verified); live SKILL.md carries the same edit uncommitted by design.
+
+### BDR-079 — profile `set` symmetric on managed externals + MCPs [accepted] (2026-07-20)
+Audit (user ask "profile toggles externals both ways?"): ASYMMETRIC. Enable side OK — gstack on-demand from submodule when pack off (shared `skills-disabled/gstack__*` convention with toggle-external.sh, interoperable), externals restored from parked, magic delegated to toggle-external. Disable side MISSING: `cmd_set` trimmed only gstack + MANAGED_PLUGINS → `set backend` left emil/frontend-design/design-motion/impeccable active + magic registered; SKILL.md claimed both-ways toggle (true only at enable). Shipped: (1) `MANAGED_EXTERNALS` (emil-design-eng, frontend-design, design-motion-principles, impeccable = exact union of profile `external` usage; darwin-skill excluded — not task-type-driven) + `MANAGED_MCPS` (magic) allowlists, same doctrine as MANAGED_PLUGINS; (2) cmd_set refactored to 4 trim helpers (`disable_{gstack,plugins,externals,mcps}_not_in`) — symmetric, nothing outside allowlists ever auto-touched; (3) enable_skill external += from-source fallback (`ln -sf skills-external/<name>`, mirrors toggle-external) — closes the "missing symlink" warn; (4) stale usage() NOTE ("NOT toggled automatically") + SKILL.md fixed. Hermetic test profile-set-managed.test.sh 16 checks: fixture repo (both *_REPO_OVERRIDE), fake `claude` shim on PATH logging calls + flat-file MCP registry — gstack on-demand, external from-source, park/restore round-trip, magic add/remove calls, non-managed untouched. shellcheck + make test green. Branch feature/profile-managed-externals, unmerged (human gate).

.claude/memory/journal.md

@@ -417,3 +417,4 @@ rules:
 ## 2026-07-20
 - ctx7 coverage audit (user ask "ctx7 appelé à chaque techno ?") → verdict PARTIAL. 4 gaps: find-docs question-only, /feat //bugfix executors blind, ad-hoc coding uncovered, fast-libs hardcoded 3×. All 4 closed → BDR-078 (fast-libs.sh single source + ctx7-reminder hook + description trigger + executor-brief rule). fast-libs test 11/0, make test + review-guards green. feature/ctx7-coverage, UNMERGED.
 - v1.2.0 cut + pushed (release-candidate flow: prep/finish via release-executor, tag on main 51b6572). CHANGELOG backfilled at prep: 10 entries added to Unreleased (plan-challenge, seo-data verbs, model-tiering v2, integrity pass, safe_fetch/url-guard) — was ctx7-only. /doc full post-release: README model-routing table v1→v2 reframe + ctx7 two-surface wording, chore/doc-sync-v1.2.0 merged. All pushed on explicit go.
+- profile↔toggle-external audit (user) → enable side already symmetric (gstack on-demand LIVE), disable side missing → BDR-079: MANAGED_EXTERNALS+MANAGED_MCPS trim at set, external from-source fallback, 16-check hermetic test (claude shim). feature/profile-managed-externals, UNMERGED.