docs: finalize P2 manuals, project state, and install-doc service contract

docs/install/local-workspace-registry.md

@@ -19,6 +19,17 @@ Compose stack. Never put credentials in workspace YAML, Git, browser drafts, dia
 | Qdrant | Internal | Mandatory private Compose semantic service; persistent `qdrant-data` volume. |
 | Ollama embedding | Internal | Mandatory private Compose semantic service for `qwen3-embedding:0.6b`. |
 
+
+## Host preprocessing (P2)
+
+The installed native `thothctl` is the only host entrypoint for workspace preprocessing
+(introspection+LSH, FK review, schema indexing, HTTP Evidence). Use
+`thothctl --installation <thothii-installation.yaml> workspace <command> --workspace <id> [--json]`
+per `docs/contracts/workspace-preprocessing-cli.md` and the P2 walkthrough in
+`docs/testing/p2-p6-manual-verification.md`. Preprocessing runs through the profile-gated
+`workspace-maintenance` Compose service; it never starts a backend/Pi/frontend listener and never
+attaches Git credentials.
+
 ## Prerequisites
 
 - macOS: Docker Desktop, Git, and sufficient volume disk space. Git Credential Manager is useful