The mode gate — mechanism under the scenarios

The scenarios describe behavior; this page is the machinery they share. One flag, two modes, and three things that flip with it. The decision rationale lives in ADR-139 and the tuning mechanics in the evidence record ADR-183; this is the operational map.

The flag

The ways language setting (ways.language in ways settings), default auto; auto, en and unset all mean English mode. It is layered: the project ways.yaml overrides the user-scope ~/.config/agent-ways/config.yaml. The effective switch is the user-scope value, the layer ways-localize writes, and that skill is the only thing that writes a non-English value. It is read once, upstream: components do not each sniff for locale data; they consult the mode. ways status --json reports the resolved value as output_language.

What flips with it

flowchart TD
    F[language] --> M{English mode?}
    M -->|"yes — English mode"| EN[corpus: English only<br/>matcher: embedding, 384-dim English model only<br/>locale tuning: not in the flow]
    M -->|"no — localized mode"| LO[corpus: + multi, English-root anchored<br/>matcher: + 2nd embedding lane, 768-dim multilingual model<br/>locale tuning: root-anchored, --lang scoped]

    classDef config fill:#fbbf24,color:#1a1a1a,stroke:#4a5568
    classDef process fill:#2d7d9a,color:#ffffff,stroke:#4a5568
    classDef done fill:#2d8e5e,color:#ffffff,stroke:#4a5568
    classDef core fill:#7c3aed,color:#ffffff,stroke:#4a5568

    class F config
    class M process
    class EN done
    class LO core

1. Corpus build (corpus.rs). Localized mode emits each way's English root into the multilingual corpus (embedded with the multilingual model) as the anchor, plus the localized aliases. English mode builds the English corpus only.
2. Match compute (scan/scoring.rs). Both modes match by embedding; the difference is the model, not the method. English mode runs the 384-dim English model only; localized mode adds the 768-dim multilingual model as a second lane (English lane still runs too). The matcher gates that second lane on the mode, not on corpus-file presence, so English mode never loads the heavier 768-dim model — a per-prompt saving on every match for the default install.
3. Locale tuning (tune.rs). The root-anchored locale-alias audit runs only in localized mode, scoped by --lang. (English corpus tuning, meaning the vocabulary health and sibling discrimination of the English ways themselves, is a separate, always-on concern: a new or materially changed English way retunes regardless of mode.) There is no empty / "0/0" path to special-case, because locale tuning is simply never invoked in English mode.

Root-anchored tuning, in one breath

Fidelity is alignment to the English root, measured per language and independently — cosine(localized alias, English root). Not agreement among sibling translations (which would let a drifting cluster self-certify). Discrimination stays as alias − top_confuser: the alias must not collide with a different way. A language passes the ways-localize gate when every alias both aligns to its root and avoids collision. This works identically for one language or many — the English root is the fixed peer that makes N=1 meaningful. Full treatment: ADR-183 and ADR-125.