Implement scripts/agent-brief.sh — minimal-token context briefing

[infraax]

Task: Agent Briefing Script

Parent epic: #13 (Infrastructure)

What to do

Create scripts/agent-brief.sh — a single command that generates an ~80-line structured brief for an incoming agent. The brief replaces reading multiple files cold.

Output format

=== VECTORBRAIN AGENT BRIEF — 2026-03-25T17:14Z ===
Milestone: 1 — Robot Connection (in progress)
Last hardware test: none (M0 only)

ACTIVE AGENTS:
  claude-code-web | session 20260325-170955 | bootstrap/backlog

OPEN ISSUES — READY (claimable now):
  #14 [xs][go]  Add vector-go-sdk to go.mod
  #15 [s][go]   Implement BrainRegistry
  #17 [s][go]   Acquire RESERVE_BEHAVIORS control

RECENT COMMITS (last 5):
  1ab2f7a  feat(workflow): add agent-claim/release, MEMORY.md  [claude-code-web]
  11674b1  feat(workflow): implement multi-agent git workflow   [claude-code-web]
  07a1159  [milestone-0] init: VectorBrain cognitive layer

TEST STATUS:
  Go:     run `make test` to verify
  Python: 24 passing (last known)

FILES RECENTLY TOUCHED:
  scripts/*, MEMORY.md, WORKFLOW.md, CLAUDE.md

KNOWN TRAPS:
  - Always use GOMODCACHE=.gomodcache for Go commands
  - No markdown in SayText calls
  - Events are non-blocking — never block the Go event goroutine
=== See WORKFLOW.md for agent protocol ===

Implementation notes

• Reads from: agent-sessions.jsonl (active sessions), git log (recent commits + trailers), MEMORY.md (traps + test status), GitHub API (open ready issues, requires GITHUB_TOKEN)
• Falls back gracefully if GITHUB_TOKEN not set — shows git state only
• Fast: should complete in under 2 seconds
• Output goes to stdout — agent reads it, nothing is written

Integration

• Called from .claude/settings.json SessionStart hook (see issue Implement scripts/issue-context.sh — per-issue focused context #22)
• Agents can also call it manually at any time: ./scripts/agent-brief.sh

Definition of done

Running ./scripts/agent-brief.sh outputs a complete brief in under 2s. Active sessions, ready issues, recent commits all visible.