Synapse A2A Communication

Inter-agent communication framework via Google A2A Protocol.

Quick Reference

Task	Command
List agents (Rich TUI)	`synapse list` (event-driven refresh via file watcher with 10s fallback, ↑/↓ or 1-9 to select, Enter/j jump, k kill, / filter)
Send message	`synapse send <target> "<message>" --from <sender>`
Wait for reply	`synapse send <target> "<message>" --response --from <sender>`
Reply to last message	`synapse reply "<response>" --from <agent>`
Emergency stop	`synapse send <target> "STOP" --priority 5 --from <sender>`
Stop agent	`synapse stop <profile\|id>`
Check file locks	`synapse file-safety locks`
View history	`synapse history list`
Initialize settings	`synapse init`
Edit settings (TUI)	`synapse config`
View settings	`synapse config show [--scope user\|project]`
Show instructions	`synapse instructions show <agent>`
Send instructions	`synapse instructions send <agent> [--preview]`
Version info	`synapse --version`

Tip: Run synapse list before sending to verify the target agent is READY.

Sending Messages (Recommended)

Use synapse send command for inter-agent communication. This works reliably from any environment including sandboxed agents.

bash

synapse send gemini "Please review this code" --from claude
synapse send claude "What is the status?" --from codex
synapse send codex-8120 "Fix this bug" --priority 3 --from gemini

Important: Always use --from to identify yourself so the recipient knows who sent the message and can reply.

Target Resolution (Matching Priority):

•Exact ID: synapse-claude-8100 (direct match)
•Type-port: claude-8100, codex-8120, opencode-8130, copilot-8140 (shorthand)
•Type only: claude, gemini, codex, opencode, copilot (only if single instance)

Note: When multiple agents of the same type are running, type-only targets (e.g., claude) will fail with an ambiguity error. Use type-port shorthand (e.g., claude-8100) instead.

Choosing --response vs --no-response

Rule: If your message asks for a reply, use --response

Message Type	Flag	Example
Question	`--response`	"What is the status?"
Request for analysis	`--response`	"Please review this code"
Status check	`--response`	"Are you ready?"
Notification	`--no-response`	"FYI: Build completed"
Delegated task	`--no-response`	"Run tests and commit"

bash

# Question - needs reply
synapse send gemini "What is the best approach?" --response --from claude

# Delegation - no reply needed
synapse send codex "Run tests and fix failures" --from claude

Roundtrip Communication (--response)

For request-response patterns:

bash

# Sender: Wait for response (blocks until reply received)
synapse send gemini "Analyze this data" --response --from claude

# Receiver: Reply using the reply stack
synapse reply "Analysis result: ..." --from gemini

The --response flag makes the sender wait. The receiver should reply using the synapse reply command.

Reply Stack: Synapse automatically tracks sender info when you receive messages. Use synapse reply for responses - it automatically knows who to reply to.

Receiving and Replying to Messages

When you receive an A2A message, it appears as plain text - the message content is sent directly to your terminal without any prefix.

Replying to Messages:

Synapse uses a Reply Stack to track sender information. When you receive a message, the sender's info is automatically stored. To reply:

bash

# Use the reply command (--from is required in sandboxed environments)
synapse reply "Here is my analysis..." --from <your_agent_type>

Example - Question:

code

Received: What is the project structure?
Reply:    synapse reply "The project has src/, tests/..." --from codex

Example - Delegation:

code

Received: Run the tests and fix failures
Action:   Just do the task. No reply needed unless you have questions.

Priority Levels

Priority	Description	Use Case
1-2	Low	Background tasks
3	Normal	Standard tasks
4	Urgent	Follow-ups, status checks
5	Interrupt	Emergency (sends SIGINT first)

bash

# Normal priority (default)
synapse send gemini "Analyze this"

# Higher priority
synapse send claude "Urgent review needed" --priority 4

# Emergency interrupt
synapse send codex "STOP" --priority 5

Agent Status

Status	Meaning	Color
READY	Idle, waiting for input	Green
WAITING	Awaiting user input (selection, confirmation)	Cyan
PROCESSING	Busy handling a task	Yellow
DONE	Task completed (auto-clears after 10s)	Blue

Verify before sending: Run synapse list and confirm the target agent's Status column shows READY:

bash

synapse list
# Output:
# NAME                  TYPE    STATUS      PORT   WORKING_DIR
# synapse-claude-8100   claude  READY       8100   my-project
# synapse-gemini-8110   gemini  WAITING     8110   my-project  # <- needs user input
# synapse-codex-8120    codex   PROCESSING  8120   my-project  # <- busy

Status meanings:

•READY: Safe to send messages
•WAITING: Agent needs user input - use terminal jump (see below) to respond
•PROCESSING: Busy, wait or use --priority 5 for emergency interrupt
•DONE: Recently completed, will return to READY shortly

Interactive Controls

In synapse list, you can interact with agents:

Key	Action
`1-9`	Select agent row (direct)
`↑/↓`	Navigate agent rows
`Enter` or `j`	Jump to selected agent's terminal
`k`	Kill selected agent (with confirmation)
`/`	Filter by TYPE or WORKING_DIR
`ESC`	Clear filter first, then selection
`q`	Quit

Supported Terminals:

•iTerm2 (macOS) - Switches to correct tab/pane
•Terminal.app (macOS) - Switches to correct tab
•Ghostty (macOS) - Activates application
•VS Code integrated terminal - Opens to working directory
•tmux - Switches to agent's session
•Zellij - Focuses agent's terminal pane

Use case: When an agent shows WAITING status, use terminal jump to quickly respond to its selection prompt.

Key Features

•Agent Communication: @agent pattern, priority control, response handling
•Task History: Search, export, statistics (synapse history)
•File Safety: Lock files to prevent conflicts (synapse file-safety)
•Settings: Configure via settings.json (synapse init)

References

For detailed documentation, read:

•references/commands.md - Full CLI command reference
•references/file-safety.md - File Safety detailed guide
•references/api.md - A2A endpoints and message format
•references/examples.md - Multi-agent workflow examples