name: project-context description: Background knowledge about the Agent Lens VS Code extension architecture. Preloaded by agents for project context. user-invocable: false

Agent Lens — Project Architecture

VS Code extension that visualizes AI agent workflows across GitHub Copilot, Claude Code, and OpenAI Codex.

Tech stack

TypeScript, Lit 3, D3.js 7 + d3-dag, Vitest 3, esbuild, js-yaml

Source structure

src/
  extension.ts              — Activation, command registration, watchers
  models/                   — Interfaces: Agent, Skill, Session, Graph, Metrics
  parsers/                  — Session discovery and parsing (pure functions)
    sessionProvider.ts      — SessionProvider interface (all providers implement this)
    copilotProvider.ts      — GitHub Copilot session discovery
    claudeProvider.ts       — Claude Code session discovery
    codexProvider.ts        — OpenAI Codex CLI session discovery
    agentParser.ts          — Agent frontmatter + handoff parsing
    skillParser.ts          — Skill frontmatter parsing
    frontmatterParser.ts    — YAML frontmatter extraction
    discovery.ts            — Glob-based agent/skill file discovery
    sessionRegistry.ts      — Coordinates providers, dedupes, watches changes
    detectors.ts            — Agent/skill detection helpers
  analyzers/
    graphBuilder.ts         — Agents + skills → DAG with handoff edges
    metricsCollector.ts     — Token usage, agent/model/tool/skill counts
  views/
    treeProvider.ts         — Sidebar tree (agents, skills, actions)
    graphPanel.ts           — Graph webview panel controller
    metricsPanel.ts         — Metrics webview panel controller
    sessionPanel.ts         — Session explorer panel controller
webview/
  graph.ts                  — D3 graph visualization (Lit custom element)
  layout.ts                 — D3-DAG Sugiyama layout algorithm
  metrics.ts                — Metrics dashboard webview
  session.ts                — Session explorer (timeline)

Key patterns

• Parsers are pure functions — no side effects, easy to test
• SessionProvider interface — implement to add new agent sources
• Webview ↔ extension — message passing via postMessage/onDidReceiveMessage
• Panel controllers (src/views/*Panel.ts) manage webview lifecycle
• Models define all shared types in src/models/

Build commands

• npm run build — Build extension + webview
• npm test — Run all tests (vitest)
• npx vitest run <path> — Run a single test file
• npm run build:ext — Build extension only
• npm run build:webview — Build webview only

Graph model types

NodeKind: agent, skill, builtin-agent, claude-agent EdgeKind: handoff, tool-call, skill-use

Conventions

• Conventional Commits (feat(scope):, fix(scope):, etc.)
• TDD: red-green-refactor
• Tests co-located: *.test.ts next to source files
• Branch per issue, merge via PR