feat(mcp): add daemon control tools

[corylanou]

Description

Adds seven daemon-control tools to the official MCP SDK surface:

• litestream_list and litestream_daemon_info are annotated read-only.
• litestream_sync, litestream_start, litestream_stop, litestream_register, and litestream_unregister are annotated mutating and destructive.
• Each tool calls the corresponding HTTP endpoint over the daemon Unix socket and accepts optional socket and timeout inputs.
• Sync exposes the daemon's wait behavior for remote replication.
• Successful daemon responses are returned as JSON text, while missing or refused sockets return a clear no-daemon error.

Motivation and Context

The daemon already exposes /list, /sync, /info, /start, /stop, /register, and /unregister, but the MCP server did not register tools for those endpoints. Assistants therefore could not inspect or control the running daemon through MCP.

The MCP behavior test now exercises all seven methods, paths, request bodies, and responses over a real Unix socket. A separate matrix verifies that every tool reports no Litestream daemon is running when the socket is absent.

Scope

In scope:

• Official Go SDK tool registration and annotations.
• Unix-socket IPC requests with context and timeout propagation.
• Daemon response and connection error handling.
• Tool schema, behavior, and no-daemon tests.

Not in scope:

• Structured outputs beyond the existing text output contract.
• Standalone MCP transport changes.
• Changes from other MCP feature branches.

Behavior Change

Scenario	Before	After
List or inspect a running daemon	No MCP tool	Read-only MCP tools call daemon IPC
Sync, start, stop, register, or unregister	No MCP tool	Destructive MCP tools call daemon IPC
Sync and wait for remote replication	Unavailable through MCP	litestream_sync accepts wait: true
Daemon is not running	No daemon tool behavior	Clear no-daemon tool error

How Has This Been Tested?

• go test -race ./...
• go vet ./...
• go mod verify
• pre-commit run --all-files
• validation_dir=$(mktemp -d); go build -o "${validation_dir}/litestream" ./cmd/litestream
• validation_dir=$(mktemp -d); GOOS=windows CGO_ENABLED=0 go test -c -o "${validation_dir}/litestream.test.exe" ./cmd/litestream

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (would cause existing functionality to not work as expected)

Checklist

• My code follows the code style of this project (go fmt, go vet)
• I have tested my changes (go test ./...)
• I have updated the documentation accordingly (not needed; no configuration or CLI behavior changed)

Related

• Stacked on refactor(mcp): migrate to the official modelcontextprotocol/go-sdk #1378
• Closes feat(mcp): add daemon-control tools (list/sync/info/start/stop/register/unregister) #1372

[github-actions]

PR Build Metrics

✅ All clear — no issues detected

Check	Status	Summary
Binary size	✅	38.38 MB (+92.0 KB / +0.23%)
Dependencies	✅	No changes
Vulnerabilities	✅	None detected
Go toolchain	✅	1.25.12 (latest)
Module graph	✅	1248 edges (0)

Binary Size

	Size	Change
Base (eb6c415)	38.29 MB
PR (5967896)	38.38 MB	+92.0 KB (+0.23%)

Dependency Changes

No dependency changes.

govulncheck Output

=== Symbol Results ===

No vulnerabilities found.

Your code is affected by 0 vulnerabilities.
This scan also found 0 vulnerabilities in packages you import and 1
vulnerability in modules you require, but your code doesn't appear to call these
vulnerabilities.
Use '-show verbose' for more details.

Build Info

Metric	Value
Build time	2s
Go version	go1.25.12
Commit	5967896

History (3 previous)

Commit	Updated	Status	Summary
07adbd1	2026-07-18 23:56 UTC	✅	38.38 MB (+92.0 KB / +0.23%)
d4b16a9	2026-07-18 21:11 UTC	✅	38.36 MB (+92.0 KB / +0.23%)
c62a03d	2026-07-17 17:29 UTC	✅	38.36 MB (+92.0 KB / +0.23%)

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_{🤖 Updated on each push.}