feat: unify installation model catalog

PROJECT_STATE.md

@@ -1,6 +1,6 @@
 # ThothII — Project State
 
-Last updated: 2026-08-31.
+Last updated: 2026-09-02.
 
 This file is the short operational snapshot. Stable commands and the architecture mental model
 live in `AGENTS.md`; current design and runtime contracts live under `docs/architecture/`,
@@ -59,10 +59,28 @@ tht --installation /absolute/path/thothii-installation.yaml workspace preprocess
 These commands use the profile-gated `workspace-maintenance` service. The former standalone
 preprocessing Compose fixtures are retired.
 
-Workspace descriptors use schema v3. For PSD, workspace content and runtime roots point to the
+Workspace descriptors use schema v4 and contain only database, Evidence, diagnostics, and binding
+concerns; model, provider, embedding, and vector-store configuration is installation-owned. For
+PSD, workspace content and runtime roots point to the
 separate uncommitted repository `/Users/mp/projects/tht-workspace-psd`. Secrets remain outside
 Git and are supplied only through installation-local protected files.
 
+## Installation Model Catalog
+
+`thothii-installation.yaml` schema version 2 is the only operator-authored source for session,
+metadata-generation, and embedding models. The host `tht` lifecycle validates `modelCatalog` and
+regenerates the backend catalog, Pi `models.json`/`settings.json`, and Compose override under the
+installation-local `generated/` directory. Those projections are replaceable runtime adapters:
+they are not edited, backed up, or treated as configuration.
+
+Session and metadata defaults use canonical `provider/model` IDs. Provider authentication declares
+one explicit mode (`secret_env`, `pi_auth`, or `none`); `secret_env` names a protected bundle key.
+The backend settings store now owns only the selected workspace and thinking level. Existing v1
+installations use the explicit catalog migration command; schema-v3 workspace descriptors are
+converted deterministically in their curator-owned repository before commit. Strict runtime loading
+does not silently infer or merge legacy sources. ADR 0013 and
+`docs/plans/2026-09-02-installation-model-catalog.md` record the decision and implementation.
+
 ## Database management
 
 The database, table, and authoritative physical-schema catalog slices are implemented. Database
@@ -164,7 +182,8 @@ available only when no local start, worker, or helper is live. Runs remain inspe
 live SSE log with ordered polling fallback; there is no automatic resume or user-facing generation
 CLI. ADRs 0009–0010 record the runtime and source-sampling decisions.
 
-Metadata-generation setup accepts the protected `DEEPSEEK_API_KEY` and `ZAI_API_KEY` references.
+The Installation Model Catalog accepts the protected `DEEPSEEK_API_KEY` and `ZAI_API_KEY`
+references for metadata-generation providers.
 It also accepts a model with no secret reference only when its OpenAI-compatible endpoint is
 explicit; this covers the VPN-only AritmoLab Qwen 3.6 server without creating a fake operator
 credential. The Python client supplies only its fixed non-secret compatibility placeholder.