ADR 0101: Retire the [features] toggles

Amendments.

• Vocabulary: current spellings are standards (formerly ratchets), [jobs] / [jobs.<name>] (formerly [capabilities] / [checks.<name>]), and known/custom job (formerly gate capability / custom check); the decision and reasoning are unchanged.

Status: accepted; amends ADR 0020 (which introduced the [features] set) and completes the trajectory of ADR 0045 (which removed mcp from it)

ADR 0020 introduced [features] so a disabled subsystem could vanish coherently: verbs hidden, hooks unwritten, guidance sections dropped, doctor checks skipped. The set has only ever shrunk in spirit — ADR 0045 promoted mcp to core — while growing in members (coupling joined later). Today six toggles gate five subsystems across the dispatcher, the hook writers, the guidance compiler, doctor, the MCP server, and the gate planner.

Three observations, made while every toggle still has zero external users:

1. The toggle test. A subsystem that costs nothing when unused needs no switch. Worktrees you never start, standards you never define, an advisory verb you never invoke — the escape is behavioral. A toggle earns its keep only when an unused feature still imposes a real cost.
2. Each toggle is a combinatorial promise. Both states of every toggle must keep working forever, multiplied together — yet the off-states are never self-hosted (this repo runs everything on), which makes them the permanently untested half of the matrix.
3. The pre-release asymmetry. Adding a toggle later is backwards-compatible; removing one later is a breaking change. Keeping an unproven toggle now is the only irreversible choice on the table.

There is also a live single-source-of-truth violation: [worktree].enabled duplicates [features].worktrees in the shipped template — two keys claiming the same fact.

• The [features] section is removed entirely; every subsystem is core. The feature/job terminology split dissolves with it — [jobs] is the gate's command table.
• Worktrees are discern's spine, not an option. The isolated-worktree workflow is core to how discern works; "discern uses worktrees" is a product sentence with no configuration attached. Verbs, hooks, guidance, and doctor checks are always wired. Nothing forces a session to call start — not using the workflow remains the escape, configuring it away does not. The duplicate [worktree].enabled key retires at the same time.
• Standards activate by presence, not by toggle. With no [standards] tables defined the subsystem is naturally inert; defining one is the act that turns it on. The standards guidance section compiles in only when at least one standard is configured — gating on configuration, not on a switch.
• Guidance, docs, and the coupling advisory are core. Guidance is discern's only channel to agents — disabling it severed the nervous system. The map is the product. Coupling is read-only, self-calibrating, and invoked on demand; its one real cost decision ([coupling].in_gate) is behavior configuration and stays.
• Skills keep one knob, in reduced form: [skills].exclude. Materialized skills are the single subsystem that imposes a cost while unused — every skill occupies context in every agent session. A per-skill exclusion list (additive, by name) meets that honestly; a whole-subsystem kill-switch was the blunt version of it.
• A schema migration drops [features] and [worktree].enabled from existing configs, noting any non-default value it discards.

• The dispatcher, hook writers, guidance compiler, doctor, MCP server, and gate planner lose their feature-gating branches; the VERB_FEATURE map and its parity-test leg go with them. The test matrix roughly halves several times over.
• discern.toml loses its most confusing section (the feature-vs-job distinction has needed a warning comment since it existed) and the docs lose the concept.
• A future subsystem that genuinely passes the toggle test can get a toggle back compatibly; nothing re-opens by default.
• Users who want less discern do it behaviorally (don't start worktrees, define no standards, exclude skills by name) — every escape remains, none of them configurational existence-switches.

• Keep the full set. Rejected: five subsystems × two states of untested surface, held open forever, for preferences no user has expressed.
• Keep only [features].worktrees. Rejected: worktrees are the subsystem least eligible — the whole workflow model assumes isolation, and an install with worktrees off is a discern nobody dogfoods or documents.
• Replace toggles with setup-time profiles/presets. Rejected as redundant: presets already shape what setup writes; a runtime existence-toggle is a different and heavier promise.