* feat: modular system message composition with admin prompt policies (#267)
Replace the monolithic persona+tools block in _init_system_messages()
with a modular composition harness (turnstone/prompts/). System messages
are now assembled from five typed layers: BASE (persona), ENV (client
surface — web/cli/chat), CONTEXT (datetime, timezone, username), TOOLS
(usage patterns), and POLICIES (behavioral rules with tool gating).
Prompt policies are admin-managed via a new Prompts tab in the Governance
group (CRUD with modal forms, tool gating, priority ordering, enable/disable).
DB policies override file-based defaults by name; file-based policies serve
as deployment defaults. Migration 031 adds the prompt_policies table.
ClientType is threaded end-to-end from channel adapters through the SDK,
HTTP API, WorkstreamManager, and session factory to ChatSession. Discord
sessions now receive chat-optimized formatting (no tables, no Mermaid,
concise output) instead of the web UI's rich markdown instructions.
* fix: address CI failures and Copilot review feedback
- Add client_type param to CLI session_factory (mypy protocol match)
- Add prompt policy CRUD to PostgreSQL backend (test-postgres CI)
- Fix ClientType resolution: compare against enum values, not members
- Fix null client_type coercion (body.get returns None, not "")
- Use local time with astimezone() instead of UTC with local tz name
- Sanitize tool_gate in update endpoint (coerce null to empty string)
Patrick Buckley
3ce66960bc