LakshmanTurlapati/FSB

Milestone: Multi-Agent Tab Concurrency -- pairs with FSB extension v0.9.60.

Note: the npm package was published manually on 2026-05-07. The mcp-v0.8.0 tag and this release are catching up so the GitHub release matches the npm registry.

Install / Update

npx -y [email protected]

Or install globally:

npm i -g [email protected]

Install into MCP clients:

npx fsb-mcp-server install --all

What's new

Multi-Agent Tab Concurrency

• New per-session/task agent_id minted by FSB via crypto.randomUUID(). MCP callers cannot supply IDs; the server captures via agent:register on first tool dispatch.
• Tab-ownership enforcement on every MCP tool dispatch with typed errors: TAB_NOT_OWNED, TAB_INCOGNITO_NOT_SUPPORTED, TAB_OUT_OF_SCOPE, AGENT_CAP_REACHED, NO_OWNED_TAB, AMBIGUOUS_TAB.
• Per-bindTab ownership_token (fresh UUID per binding) prevents tab-ID-reuse exploitation.
• Forced-new-tab pooling, lock release on disconnect (10s grace), no idle timeout.
• SW-eviction recovery via chrome.storage.session write-through + hydrate-time reconciliation.
• End-to-end coverage in tests/multi-agent-regression.test.js (6 cases, 6/6 green).

back MCP tool (BACK-01..05)

• Ownership-gated single-step browser-history back on the agent's owned tab.
• Returns { status, resultingUrl, historyDepth } where status is one of ok | no_history | cross_origin | bf_cache | fragment_only.
• pageshow-based 2s settle verification; cross-origin BF-cache resilience reuses the v0.9.11 path.
• Background-tab compatible.

run_task return-on-completion (Phase 239)

• Returns when automation actually completes (via fsbAutomationLifecycleBus), not at an arbitrary timer ceiling.
• 600s safety net (was 300s) at both mcp/src/tools/autopilot.ts and extension/ws/mcp-bridge-client.js.
• 30s heartbeat ticks via notifications/progress, carrying alive, step, elapsed_ms, current_url, ai_cycles, last_action under params._meta. MCP host clients (Claude Code, Cursor, Codex, OpenClaw) no longer hit per-tool timeouts on long automations.
• Task lifecycle persisted in chrome.storage.session keyed by task_id. On SW eviction, server emits partial_outcome with disposition: 'sw_evicted' if the bridge cannot recover.

Tool description updates (MCP-07)

• Every manual tool description now documents that agent_id is FSB-issued, tab_id is agent-scoped, the cap is configurable, ownership is enforced, and the typed error codes the tool can return are enumerated.
• run_task, start_visual_session, end_visual_session, back, stop_task, get_task_status carry the full multi-agent contract block.

Post-action change_report (Phase 245)

• Every action tool returns a compact change_report describing what the action mutated, so the agent doesn't need to follow up with read_page / get_dom_snapshot.
• Read-only/info/wait tools EXCLUDED from the change_report field.
• 2400-byte cap (~600 tokens) with top-N truncation.

Agent-scoped tab resolution + open_tab background-default (Phase 246)

• read-only.ts, vault.ts, manual.ts, visual-session.ts, autopilot.ts, and agents.ts all thread agentId and optional tab_id through the bridge payload.
• Optional tab_id added to all 6 read-only tool MCP schemas, start_visual_session, and 35 action-tool input schemas. Auto-resolves when omitted; enforces ownership when provided.
• Schema bridge transforms (schema-bridge.ts) explicitly forward tab_id for press_key, drag_drop, click_at, drag, fill_sheet.
• open_tab defaults to background. Foreground requires explicit active: true.
• mcp/ai/tool-definitions.cjs is byte-identical to extension/ai/tool-definitions.js (~74,845 bytes), validated by a permanent canary test (tests/tool-definitions-parity.test.js).

Dependencies

• @modelcontextprotocol/sdk ^1.29.0
• ws ^8.19.0
• zod ^3.24.0

Compatibility

• Pairs with FSB Chrome extension v0.9.60 (released separately).
• Tested against MCP host clients: Claude Code, Cursor, Codex, Windsurf, OpenClaw.

Full per-feature changelog: mcp/CHANGELOG.md. Milestone audit: .planning/milestones/v0.9.60-MILESTONE-AUDIT.md.