feat(memory): env-aware backend + memory in default plugin set

[rrader26]

Summary

PR α of the ThinkFleet Memory Bridge slice. Makes the Memory Pack a zero-config default — the MCP server now picks the right backend based on what's in the environment, and exposes agentmark_memory_* tools whether or not SaaS creds are present.

This is the foundation for: install ThinkFleet Desktop → log in → every AI tool (Claude Code, Cursor, Codex, Copilot, Windsurf) gets persistent hierarchical memory automatically.

What's in

detectMemoryBackend() — env-aware cascade

Env state	Backend	Behavior
All of THINKFLEET_BASE_URL + THINKFLEET_PROJECT_ID + THINKFLEET_API_KEY set	ActivepiecesMemoryBackend	Memory flows to SaaS, available across machines
None set	LocalFileMemoryBackend	Legacy default, on-disk, offline-safe
Some-but-not-all set	Throws MemoryBackendConfigError	Refuses to silently fall back
API key missing sk- prefix	Throws	Truncated to first 4 chars in error — no leak

Refusing to silently fall back to local on partial creds matters: a typo in one variable shouldn't quietly demote a user from "memory syncs to my team" to "memory only on my disk."

Dispatcher integration

• createDispatcherState() always builds a memory plugin alongside web + pdf + desktop.
• On misconfiguration: memory disabled, reason logged to stderr (which MCP clients surface to the user), rest of the server stays alive.
• Selected backend logged at startup via describeMemoryBackend() — credential-free description, safe for any log sink.

Threat model (codified in the docstrings)

• API key only ever lives in process env. Upcoming desktop installer (PR γ) reads it from the OS keychain at install time and passes it via the MCP install CLI (PR β).
• Error messages never echo back the supplied API key.
• Backend description never embeds credentials.

Tests

• test/memory/detect-backend.test.ts — 16 cases covering each branch of the cascade, error-message sanitization, whitespace handling.
• test/mcp/default-memory-plugin.test.ts — 5 cases covering dispatcher integration: tools register, partial creds disable cleanly, malformed keys don't leak to logs.

Full suite: 540 passed, 10 pre-existing skips. Typecheck clean.

Backwards compatibility

Strictly additive:

• Callers passing an explicit plugins array to createMcpServer() see no change.
• Default callers (most consumers) now get the memory tools registered.
• Existing LocalFileMemoryBackend behavior unchanged when env is unset.

Next PRs

• β — agentmark-mcp install --env KEY=VAL so the install CLI can write env into client config blocks safely.
• γ — ThinkFleet Desktop installer reads OS-keychain-stored creds and passes them via β.
• δ — Canonical thinkfleet-memory.skill.yaml + per-tool skill installer (Claude Code skills, Cursor rules, etc.) so agents are taught the protocol, not just given the tools.

🤖 Generated with Claude Code