MLD-1307 - Claude rewrite mcp.json

[arielamitjfrog]

Summary

• Adds Claude Code hooks that discover installed-plugin .mcp.json files and rewrite stdio MCP entries through JFrog Agent Guard (npx @jfrog/agent-guard --rewrite-mcp-json) on every SessionStart and when installed_plugins.json / known_marketplaces.json change.
• Splits Claude-specific discovery/adapters into scripts/ (safe across modules sync) and shared rewrite orchestration into vendored modules/core/ (rewrite-mcp-json.mjs, agent-guard-check.mjs, entry.mjs).
• Soft-fails by design (missing project key, gate failure, or rewrite errors log and exit 0) so sessions are never broken; emits /reload-plugins guidance when files were rewritten.
• Bumps plugin version to 0.2.20, documents the feature and env knobs in README/VENDOR, and adds CI unit tests for discovery + align scripts.

What changed

Area	Details
Hooks	SessionStart: register FileChanged watch paths, then run align; FileChanged: re-align on plugin install metadata changes
Discovery	Marketplace live trees + installed_plugins.json install paths under $CLAUDE_CONFIG_DIR (default ~/.claude)
Kill switch	JF_AGENT_REWRITE_MCP_JSON_DISABLE=1
CI	node --test for claude-mcp-json-discover and claude-align-mcp-json

Related PRs:

• agent-guard - MLD-1375 - Harness-agnostic rewrite plugins mcp.json
• jfrog-agent-hooks - MLD-1386 - Apply cross harnesses logic

Test plan

• Fresh session with Agent Guard available: SessionStart discovers plugin .mcp.json paths and rewrites stdio MCP entries
• After rewrite, hook additionalContext asks for /reload-plugins; after reload, plugin MCPs reconnect via Agent Guard
• Install/update a marketplace plugin mid-session → FileChanged fires → configs re-aligned
• Remote url / http / sse / ws MCP entries are left unchanged
• Soft-fail cases (no project key, Agent Guard unavailable, kill switch set) exit 0 and do not break the session
• node --test scripts/claude-mcp-json-discover.test.mjs scripts/claude-align-mcp-json.test.mjs passes locally / in validate workflow