msd-core/docs/adr/0010-skill-surface-budget-module.md

Skill Surface Budget Module owns install-time skill listing curation

• Status: Superseded by ADR-0011 (Skill Surface Budget Module — install-time profile staging and runtime surface control); originally Proposed (2026-05-12)
• Date: 2026-05-12

Provenance of this status (2026-07-16). This file said Proposed while the hand-maintained index in README.md recorded it as "Skill Surface Budget Module — earlier draft superseded by ADR-0011", status "Superseded by 0011". The index was right and the file was stale. When the index became a generated artifact (derived from these files), that assertion would have been silently dropped and this superseded draft would have reappeared as a live Proposed decision — so it is recorded here, at its source, instead. This is the one status corrected from the old index rather than left for ratification, because leaving it would have lost a decision the maintainer had already made.

We propose extending the existing install profile seam (msd-core/bin/lib/install-profiles.cjs) into a Skill Surface Budget Module that owns which subset of MSD's 66 skills is written to the runtime config dirs, and that owns the per-skill requires: dependency manifest used to keep that subset closed under cross-skill references. MSD currently ships a binary --minimal / full toggle; runtimes that enumerate skills (Claude Code, OpenCode, etc.) cap the <available_skills> system-prompt block at skillListingBudgetFraction of the context window (default 1% = ~2k tokens at 200k), and MSD alone consumes ~60% of that cap (#3408). Further description shrinkage is unavailable — scripts/lint-descriptions.cjs already enforces a hard 100-char ceiling and the mean is 72.5 chars. The remaining lever is surfacing fewer skills, which requires a typed profile model plus a dependency manifest, not more ad-hoc allowlists.

Decision

• Add a Skill Surface Budget Module by extending msd-core/bin/lib/install-profiles.cjs as the single owner for which commands/msd/*.md and agents/msd-*.md files are staged into the per-runtime copy pipeline.
• Replace the single MINIMAL_SKILL_ALLOWLIST constant with a typed PROFILES map keyed by profile name. Each profile is a base set of skills; the module computes the transitive closure over each skill's declared requires: set before staging.
• Add a requires: frontmatter field to every skill whose body references another MSD skill. The dependency graph in the research memo (docs/research/2026-05-12-skill-surface-budget.md §3.1) is the migration spec for this pass.
• Extend bin/install.js argument parsing to accept --profile=<name> and --profile=<name1>,<name2> (composable). Preserve --minimal / --core-only as aliases for --profile=core. Default install (no flag) remains full for back-compat.
• Persist the active profile to ~/.claude/skills/.msd-profile (and runtime-equivalent locations) so msd update re-applies the same profile instead of expanding silently to full.
• Add scripts/lint-skill-deps.cjs and wire it into the existing npm run lint:descriptions pretest gate. The lint fails if:
  • a skill body references another skill not in its requires: set, or
  • any profile would ship a skill whose requires: closure is not satisfied.
• Keep the interactive install picker behind the same AskUserQuestion-style flow already used for runtime/location selection. Non-interactive installs (CI, npx --yes) fall back to --profile=full unless overridden.

Initial Scope

First migration slice should land the profile model and one new tier above core:

1. Profile map (typed): core (current minimal, 7 skills including phase), standard (~13 skills covering the audit + main-loop + utility floor), full (current default, 66 skills).
2. requires: frontmatter added to the hot nodes of the dependency graph first: phase (38 callers), review (11), config (7), progress (5), update (5). These are the skills whose absence silently breaks others, so they need explicit required_by audit before any profile narrows them out.
3. Confirm-and-lock the latent bug fix surfaced by the audit: phase is referenced by 38 skills and now belongs in MINIMAL_SKILL_ALLOWLIST / PROFILES.core. Keep explicit coverage in minimal/core tests so this cannot regress.
4. CLI surface: --profile=, comma-composed profiles, --profile=help listing each profile's contents and token cost.
5. Profile marker persistence + msd update re-application.

It should not in the first pass:

• Build a runtime enable/disable surface (/msd:surface). Track as a follow-up ADR (see "Open questions").
• Split MSD into multiple npm packages. The packaging-level alternative was considered and rejected — see research memo §4 Option F.
• Consolidate further skills (e.g. collapsing *-phase into a dispatcher). Track separately as IA cleanup; orthogonal to surface curation.

Migration Inventory

msd-core/bin/lib/install-profiles.cjs

• Replace MINIMAL_SKILL_ALLOWLIST Object.freeze constant with PROFILES Object.freeze map of profile-name → base skill set.
• Replace isMinimalMode(mode) with resolveProfile(mode) returning a typed {name, skills: Set, agents: Set} after transitive-closure computation.
• Replace shouldInstallSkill(name, mode) with shouldInstallSkill(name, resolvedProfile).
• Replace stageSkillsForMode(srcDir, mode) with stageSkillsForProfile(srcDir, resolvedProfile). Add a sibling stageAgentsForProfile since this module now owns agent staging too (current --minimal skips agents wholesale; tiered profiles need finer control).
• Keep the existing exit-cleanup machinery (STAGED_DIRS, ensureExitCleanup) unchanged — the bug surface it covers is the same.

bin/install.js

These call sites should migrate behind the Skill Surface Budget Module:

• --minimal / --core-only flag parsing — bin/install.js:123-124
• _effectiveInstallMode plumbing + isMinimalMode() checks — bin/install.js:7634-8465 (passes through to per-runtime copy fns)
• minimal-agent skip block — bin/install.js:8167-8207 (becomes "skip agents not in profile")
• runtime-specific copy entry points that consume stageSkillsForMode — 13 sites per the existing comment in install-profiles.cjs
• usage help block — bin/install.js:508 (add --profile= documentation)

Frontmatter changes

• Add requires: field to every skill in commands/msd/*.md whose body references another MSD skill. Audit data lists the full set (docs/research/2026-05-12-skill-surface-budget.md §3.1). Estimate: 25-30 files touched in Phase 1.
• Field is optional. Absence = "no MSD-skill dependencies." lint-skill-deps.cjs enforces consistency, not presence.

New: scripts/lint-skill-deps.cjs

• Walks commands/msd/*.md, parses requires:, walks the body for msd:<name> or \b<stem>\b references to other skills (same matching rules documented in docs/research/2026-05-12-skill-surface-budget.md §3.1).
• Fails CI if requires: set ≠ actual references (modulo ignore-list for prose mentions that aren't actual dispatches).
• Walks PROFILES from install-profiles.cjs, fails if any profile's transitive closure references a skill not in the profile.
• Wires into npm run lint:descriptions (or as a sibling lint:skill-deps) and pretest.

Profile marker

• New ~/.claude/skills/.msd-profile (and per-runtime equivalents under .codex/, .cursor/, etc. as enumerated in install.js) containing the active profile name.
• Installer Migration Module (ADR-0008) gains a one-shot migration: if marker absent and skills dir matches core exactly, write core; otherwise write full. Migrations are idempotent per existing module contract.

Tests expected to move with the seam

• tests/install-profiles-*.test.cjs (any existing) — extend to assert profile resolution, transitive closure, and --profile=core,standard composition.
• New tests/skill-surface-budget-*.test.cjs covering:
  • profile closure: a profile that lists discuss-phase must transitively include phase if discuss-phase requires it
  • lint failures: a skill body that references an un-required skill makes lint:skill-deps fail
  • marker persistence: msd install --profile=standard followed by msd update preserves standard
  • minimal back-compat: --minimal resolves to --profile=core and emits the same file set as today (modulo the phase-inclusion bug fix)

Interface sketch

The module should accept typed profile intent and return a typed resolved profile:

// install-profiles.cjs (extended)
resolveProfile({
  modes: ['core' | 'standard' | 'full'],
  skillsManifest: ManifestMap,   // parsed `requires:` graph
})
// → { name: 'standard', skills: Set<string>, agents: Set<string> }

Profile composition: --profile=core,standard resolves to union(closure(core), closure(standard)). --profile=full is the identity profile (every skill).

stageSkillsForProfile(srcDir, resolvedProfile)  // returns staged dir path
stageAgentsForProfile(srcAgentsDir, resolvedProfile)  // new

Profile marker IO is typed too, not stringly:

readActiveProfile(runtimeConfigDir) // → 'core' | 'standard' | 'full' | null
writeActiveProfile(runtimeConfigDir, profileName)

Per-skill frontmatter contract:

---
name: msd:plan-phase
description: ...
requires: [phase, discuss-phase]   # MSD skills only; not Claude Code primitives
---

requires: lists MSD skills (file stems). It does not include Claude Code built-ins (Read, Bash, etc.) — those continue to live in allowed-tools: per existing convention.

Consequences

• The skill-set written by the installer becomes a typed first-class artifact, not a side effect of file copies + an allowlist constant. ADR-0008 (Installer Migration Module) gains a clean handle for safe profile migrations on upgrade.
• msd update stops silently re-expanding a --minimal install to full — a current foot-gun documented inline in install-profiles.cjs (its module-level comment recommends msd update without --minimal to "expand to the full surface"; that path remains available, but the default msd update now respects the recorded profile).
• The requires: manifest creates a new authoring obligation (~30 files in Phase 1), enforced by CI. Skill authors who add a /msd:phase reference in a new skill body have to update requires:. The lint script keeps drift low-cost.
• The phase-in-minimal latent gap (research memo §3.1) gets resolved as a side effect of adopting closure-based profile resolution — phase is auto-included whenever any minimal-loop skill requires: it.
• First-time install UX gains a profile picker. The default remains full for non-interactive (npx --yes) installs, so back-compat for CI scripts is preserved.
• The module becomes the canonical place to land future Anthropic platform features (lazy descriptions, per-plugin budgets, .disabled toggles — see Open Questions). It does not, in this ADR, use those features.
• If accepted, CONTEXT.md should gain a canonical Skill Surface Budget Module entry alongside the existing seam entries, and future architecture reviews should treat ad-hoc commands/msd/ filtering outside this seam as drift.

Open questions

• Whether the Phase-2 runtime /msd:surface command (research memo §4 Option B) should be its own ADR or an amendment to this one. Leaning separate ADR because it introduces persistent runtime state outside the install pipeline.
• Profile naming bikeshed. core / standard / full is the working proposal. Alternatives surveyed: minimal / recommended / everything, functional names (planning, audit, research). Settle in the implementation PR after a contributor poll.
• Whether the requires: field should also be consumed by /msd:help to render a "skills you have installed and what depends on what" graph. Likely yes, but out of scope for this ADR.
• Whether to keep phase explicitly listed in core forever vs relying purely on closure semantics. Current recommendation: keep explicit listing because minimal mode has a back-compat allowlist path.
• Whether telemetry (opt-in) is worth proposing to inform where the standard profile line goes. Without it, the cut points are author-intuition. Track separately; not a blocker.
• Whether the Anthropic platform asks (research memo §6 — lazy descriptions, per-plugin budgets, dependency-aware listing, .disabled toggles) should be filed before or after this ADR ships. Recommendation: file as a feedback bundle when ADR is accepted, so we ship Phase 1 unilaterally and platform improvements compose on top.

References

• Feature issue: #3408
• Research input: docs/research/2026-05-12-skill-surface-budget.md
• Existing seam being extended: msd-core/bin/lib/install-profiles.cjs
• Description budget enforcement: scripts/lint-descriptions.cjs
• Installer dispatch site: bin/install.js:123-124, :8167-8207
• See 0008-installer-migration-module.md (the migration that records the profile marker lives here)
• See 0005-sdk-architecture-seam-map.md (the seam map this module joins)