feat(loop): Phase E — closed-loop proposal engine, build/verify/run/analyze cycle

[tbitcs]

Phase E — Integrated Research Loop Upgrade

Replaces the old pick-template + run-template pattern with a closed-loop
Propose → Build → Verify → Run → Analyze pipeline.

Backend changes

New module: backend/glossa_lab/loop_proposal.py

• ProposalEngine class: ranks 2-3 experiment candidates per cycle using rule-based scoring (insight alignment, historical success, novelty)
• Anti-duplication: seen_experiments set + cooldown_map (5-cycle min)
• build_experiment(): instantiates runnable experiment from proposal
• verify_before_run(): pre-flight checks (anchor counts, corpus availability)
• analyze_result(): post-run metric extraction, trend detection, regression flags

Modified: backend/glossa_lab/pipelines/research_loop.py

• ResearchLoop.run() now uses Propose → Build → Verify → Run → Analyze
• Per-cycle timeout (300s default) with _CycleTimeoutError
• Partial results saved to outputs/partial_loop_result.json on failure
• New SSE events: proposal_selected, build_complete, verify_result, analysis_complete, cycle_timeout, gap_skipped
• get_full_results() returns top_findings and proposed_next

Modified: backend/glossa_lab/api/research_loop.py

• Event stream handles new SSE event types
• _build_synthesis() includes top_findings and proposed_next
• Queue timeout increased to 360s for longer cycles

Frontend changes

Modified: frontend/src/components/ResearchLoopPanel.tsx

• New TopFinding and ProposedNext interfaces on Synthesis
• Top findings section in RunSummary with experiment/metric/interpretation
• Proposed next experiments section with one-click Run buttons
• SSE event handling for proposal, verify, analysis, timeout, skip events
• Protocol description updated to Propose → Build → Verify → Run → Analyze

Build validation

• Frontend: npx tsc -b passes with 0 errors
• Backend: py_compile passes for all 3 modified/new Python files

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Conversation: https://app.warp.dev/conversation/74b8ed01-18ef-4b4a-999f-4ae46fd6bdf8
Run: https://oz.warp.dev/runs/019e84ec-7a75-7d7b-9fa1-ed7e944dfc53
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