# Agent Note: request-level LLM configuration and the credential seam

Status: implemented

English | [中文](2026-07-29-request-level-llm-config-credentials.zh.md)

> Scope: the first production consumers of `ctx.settings` (the two LLM adapter plugins), the new `packages/credentials/` capability family, and the `packages/util/atomic-write` extraction. The follow-up wire surface (`settings.*`/`credentials.*` RPC, secret-role masking, the web settings form) is a separate PR and not part of this note's shipped scope.

## Problem

The [settings seam](2026-07-28-user-settings-seam.md) shipped without a production consumer, and the LLM adapters were the motivating one: both froze `apiKey`/`baseURL`/catalog into adapter instances at plugin load, so a changed key or endpoint needed a process restart, and a missing key failed plugin load — the worst possible first-run posture for a personal config page ("store a key, then restart"). Secrets were also headed the wrong way: the natural move (put `apiKey` in the settings document) would have forced masking, server-side backfill on `replace`, and dotfiles-sync warnings, a mitigation stack for a problem peer products simply do not have — Codex (`env_key` + auth.json), Reasonix (`api_key_env` + home `.env`), OpenCode/Pi (`auth.json`), Claude Code (`apiKeyHelper`) all keep secrets out of configuration files.

## Decision

**Per-request resolution, not fiber rebuilds.** The adapters take an options thunk (and a per-stream credential resolver) instead of frozen construction facts, resolving once per operation — the Pi pattern, with its tested semantics: two requests straddling a change see two configurations, one request resolves exactly once, and an in-flight stream keeps the facts it started with. This deletes the entire swap machinery a rebuild design needs (`DUPLICATE_ADAPTER` ordering, `NO_ADAPTER` windows, a deferred-activation state machine) and makes a missing key a *request-time* actionable failure (`MISSING_CREDENTIAL` naming every entry point) while the route stays registered and the catalog stays browsable. The one registration-captured fact — the retry policy the `ctx.llm` registry snapshots at `registerAdapter` (plus pi-ai's route *set*) — re-registers the same adapter instance in one synchronous section when it changes.

**Secrets are references, values live behind `ctx.credentials`.** Configuration (both planes) carries `apiKeyEnv: DEEPSEEK_API_KEY`; the three-package credential seam resolves it per operation. `credentials-local` layers the live process environment (read-only, wins — a launch-time override is operator intent and must be *visibly* read-only, so shadowed writes reject instead of appearing to succeed) over `$DSH_HOME/.env` (writable, byte-preserving line edits, a quoting ladder dotenv reads back verbatim, wholesale snapshot replacement on reload so a deleted entry never lingers — the Claude Code additive-reapply lesson). Resolution order in the adapters is literal `apiKey` first (preserving the historical `config.apiKey ?? env` observable semantics), then the seam, then — only without a mounted seam — the raw environment variable.

**Per-plugin namespaces, schema ≡ `Config`.** Each adapter registers its own namespace (`llm-deepseek`, `llm-pi-ai`) with its plugin `Config` schema and its `cordis.yml` entry as the composition `base` — a settings section is the same YAML shape as the entry config, and `resolveAdapterOptions`/`resolveProfiles` stay the one explicit resolve step for both. A live snapshot failing a beyond-schema bound keeps the last good facts (the seam's last-good philosophy extended one level up); the entry config itself still fails load. pi-ai's `providers` became a dict keyed by route so base and user layers merge per provider and the route set is structural; the array shape fails loud with migration directions, and an empty dict is the valid dormant posture — a composition ships the adapter bare and every route stays a user-plane decision.

## Alternatives considered

- **A bridge plugin (`dsh-llm-models`) owning one unified `models` dict** — with per-plugin namespaces there is nothing left to bridge, and the adapter-mapping rules it needed were pure invented indirection.
- **Secrets in settings.yaml under `role('secret')` masking** — deleting the problem (references) beats mitigating it (mask + backfill + sync warnings); the coding-agent cohort is unanimous.
- **Registry-level live retry policy** — making `providerRetryPolicy` re-read per call would silently change the `ctx.llm` capture contract every registration relies on; re-registering the route in place keeps that contract and stays observable.

## Consequences

Onboarding is restart-free end to end (pinned by the `missing-credential` headless snapshot and the credentials-rotation composition tests): boot keyless, browse the catalog, store the key, prompt again. The demos mount `settings-local` + `credentials-local` by default and inline no `!!js` key plumbing. `runLoaderSmoke` gained `expectedExitCode` so a designed failure surface can be pinned rather than masked. Deferred: the wire/UI surface must redact `role('secret')` fields before any RPC exposes `describe()`, settings-layer arrays still replace wholesale (the deepseek `models` list), and a settings section cannot remove a composition-provided pi-ai route (only override or extend). Review of this seam later reworked where the store lives and who may read it, made one request resolve one configuration generation, and made route replacement atomic ([credential boundaries note](2026-07-30-credential-boundaries-and-atomic-registration.md)).
