[Docs] ADR-MF-01 — Generic Git / Features / State (design gate for PR-1) #160

Problem

The Multi-Forge architecture (v1.3.2-final) is frozen, but its first decision
cluster exists only in the external architecture document. The repository needs an
accepted ADR recording: Generic Git as the base product, features as additive
capabilities, the project-scope feature model, and the State V2 schema — before any
implementation (PR-1) starts.

Source: Multi-Forge v1.3.2-final §15 (ADR-MF-01).

Expected outcome

An accepted ADR (3–5 pages, decisions only — Context · Decision · Rejected
alternatives · Consequences) that freezes:

• Generic Git first; profiles are governance levels, features are optional
  capabilities — the two are independent ("Profiles != Features").
• The Feature model: name, scope, components[], conflicts[];
  forge-github conflicts with forge-gitlab; 0 or 1 active work forge.
• State schema V2: active_features[], a single shared project_install_state(),
  read-only V1 projection, state-last persistence, reuse of the existing
  per-project lifecycle lock.
• Legacy compatibility: forge-github compatibility default for legacy projects;
  legacy missing managed files remain absent during migration (never resurrected);
  github-templates ID preserved; gitlab-templates added; feature switch none.
• STATE_CONFLICTING_WORK_FORGE_FEATURES as the refusal for a state naming two
  work forges.
• Dogfood AGENTS.md protection; GHES support deferred until qualified.

Acceptance criteria

• ADR written in docs/adr/ following the repository series format and the
  decisions listed above; maximum 3–5 pages.
• Profiles-vs-features separation stated explicitly, with the rejected
  alternative (extending profiles into capability bundles) recorded.
• State V2 schema frozen with the V1 read-only projection and state-last
  persistence rules; no second migration transaction system.
• Legacy migration semantics frozen: compatibility default, absent files stay
  absent, templates IDs preserved, switch transaction semantics.
• Accepted by the maintainer (explicit approval recorded on this Issue or the
  PR) before PR-1 begins.
• Issue [Architecture] Separate governance profiles from optional capabilities #23 is updated with the accepted Feature model this ADR records.

Out of scope

• Implementing features/state V2 (PR-1).
• Workflow/claims neutrality (ADR-MF-02) and release V3 (ADR-MF-03).
• GHES, GitLab Self-Managed qualification, universal Forge SDK.

Context

• Issue [Architecture] Separate governance profiles from optional capabilities #23 — Feature design gate; this ADR records the design [Architecture] Separate governance profiles from optional capabilities #23 accepts.
• ADR-0009 — distribution profiles and lifecycle ownership (current model).
• ainative/lifecycle/data/profiles.json, components.json.
• Blocks PR-1.

Dependencies

• None. Blocks PR-1 ([Feature] Profiles / Features / State V2 (PR-1) #162) together with [Architecture] Separate governance profiles from optional capabilities #23.