Chat/agent harness work: request-authority model, turn contract, tool
policy/parsing/execution, clean_agent_preview streaming/thinking, ask_user
persistence, session probes, and scheduler.
Source: vendor/photocraft (ad1cff44) harness files, 3-way merged onto
upstream/dev (a8c147b2). Harness core files were independently developed
in both lineages; resolution policy documented in pr_work/C_conflicts.md
(vendor kept where ahead, upstream kept where vendor is behind; full delta
preserved in pr_work/C_upstream_delta.patch).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Move the research route domain into the canonical routes/research/ subpackage while preserving the legacy routes.research_routes import path through a sys.modules compatibility shim.
The moved canonical module is behavior-preserving, app wiring now imports the canonical route setup function, source-introspection tests point at the new canonical path, and shim regression coverage pins legacy/canonical same-object behavior plus string-targeted monkeypatch reach-through.
Refs #4082.
Refs #4071.