fusion/docs/agents.md

Agents

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Fusion uses multiple agent roles for triage, execution, review, and merge workflows.

Agent Field Parity Matrix

Every first-class editable agent field has a defined create/edit/import/template behavior. This ensures consistent round-tripping across all surfaces.

Agent Model Fields

Field	Create	Edit	Import	Notes
name	✓	✓	✓ (from manifest)	Unique identifier
role	✓	✓	✓ (mapped from manifest)	Agent capability
metadata	✓	✓	✓	Arbitrary key-value data
title	✓	✓	✓ (from manifest)	Job title/description
icon	✓	✓	✓ (from manifest)	Emoji or icon identifier
reportsTo	✓	✓	✓ (from manifest)	Parent agent ID
runtimeConfig	✓	✓	✗	Heartbeat/budget config
permissions	✓	✓	✗	Capability flags
instructionsPath	✓	✓	✗	File-backed instructions path
instructionsText	✓	✓	✓ (from manifest instructionBody)	Inline instructions
soul	✓	✓	✗	Personality/identity description
memory	✓	✓	✗	Per-agent accumulated knowledge
bundleConfig	✓	✓	✗	Structured instruction bundle

Agent Companies Manifest Fields

Manifest Field	First-Class Agent Field	Fallback
name	name	— (required)
title	title	—
icon	icon	—
role	role (mapped to AgentCapability)	custom
reportsTo	reportsTo	—
instructionBody	instructionsText	—
skills	metadata.skills	—

System-Managed Fields (Not User-Editable)

These fields are managed by the engine and cannot be directly edited:

• id — Auto-generated unique identifier
• state — Agent lifecycle state (managed by engine)
• taskId — Current working task (managed by scheduler)
• totalInputTokens / totalOutputTokens — Token usage totals (managed by engine)
• createdAt / updatedAt / lastHeartbeatAt — Timestamps (managed by system)
• lastError — Last error message (managed by engine)
• pauseReason — Reason for paused state (managed by engine)

Update-Only Fields

These fields can only be set during update (not on create):

• pauseReason — Why the agent is paused
• lastError — Last error message
• totalInputTokens — Accumulated input token count
• totalOutputTokens — Accumulated output token count

Agents View (Dashboard)

The agents surface provides:

• Agent list and status
• Detail/config panels
• Runtime metrics
• Run history
• Task assignment context

Built-In Agent Prompt Templates

Fusion includes built-in templates for role prompts:

• default-executor
• default-triage
• default-reviewer
• default-merger
• senior-engineer
• strict-reviewer
• concise-triage

These can be assigned per role using agentPrompts.roleAssignments.

Per-Agent Configuration

Agents can be configured with:

• Custom instructions
• Heartbeat interval/timeout limits
• Max concurrent heartbeat runs
• Budget governance settings
• Model overrides for heartbeat sessions

Runtime Configuration Fields

The runtimeConfig field on agents supports the following options:

Field	Type	Default	Description
enabled	boolean	true	Whether heartbeat triggers are enabled for this agent
heartbeatIntervalMs	number	—	How often the agent should wake up for heartbeat checks (ms)
heartbeatTimeoutMs	number	—	Time without heartbeat before agent is considered unresponsive (ms)
maxConcurrentRuns	number	1	Max concurrent heartbeat runs for this agent
messageResponseMode	"immediate" | "on-heartbeat"	"immediate"	How the agent responds to messages
modelProvider	string	—	AI provider override for heartbeat session
modelId	string	—	AI model ID override for heartbeat session
budgetConfig	AgentBudgetConfig	—	Token budget governance settings

Heartbeat values are validated and minimum-clamped.

Agent Instructions (Dashboard)

The Agent Detail view includes a dedicated Instructions tab for editing agent custom instructions. This replaces the previous embedded instructions editor in the Settings tab, providing a more discoverable and user-friendly experience.

Inline vs File-Backed Instructions

There are two ways to provide custom instructions:

1. Inline Instructions: Direct text entry in the dashboard textarea. Good for simple, short instructions.

2. File-Backed Instructions: A path to a .md file in the project that contains the instructions. Good for:

   • Longer, more complex instructions
   • Version control of instruction changes
   • Sharing instruction files across teams

Using the Instructions Tab

1. Open an agent from the Agents view
2. Click the Instructions tab
3. Enter inline instructions in the Inline Instructions textarea
4. Or set a path in Instructions File Path (e.g., .fusion/agents/my-agent.md)
5. When a path is set, a File Content editor appears for direct file editing
6. Save instructions using the Save Instructions button
7. Save file content separately using the Save File button

File Editor Behavior

• File content loads automatically when an instructions path is set
• Missing files (ENOENT) are treated as new files with empty content
• Non-ENOENT errors (e.g., permission denied) show an error toast
• The editor has an Unsaved changes indicator when file content is modified
• File saves are independent from instruction metadata saves

New Agent Presets (Dashboard UI)

The New Agent dialog in the dashboard provides quick-start presets for common agent roles. Each preset includes:

• Name and icon - Display identification
• Professional title - Descriptive role title
• Soul - Personality and operating principles defining how the agent thinks and communicates
• Instructions - Actionable behavioral guidelines

Preset Library Location

Preset definitions live in packages/dashboard/app/components/agent-presets/:

agent-presets/
├── index.ts              # Exports AGENT_PRESETS and helper functions
├── ceo/soul.md          # Chief Executive Officer soul
├── cto/soul.md          # Chief Technology Officer soul
├── cmo/soul.md          # Chief Marketing Officer soul
├── cfo/soul.md          # Chief Financial Officer soul
├── engineer/soul.md     # Software Engineer soul
├── backend-engineer/soul.md
├── frontend-engineer/soul.md
├── fullstack-engineer/soul.md
├── qa-engineer/soul.md
├── devops-engineer/soul.md
├── ci-engineer/soul.md
├── security-engineer/soul.md
├── data-engineer/soul.md
├── ml-engineer/soul.md
├── product-manager/soul.md
├── designer/soul.md
├── marketing-manager/soul.md
├── technical-writer/soul.md
├── triage/soul.md
└── reviewer/soul.md

Soul File Format

Each soul.md file is a Markdown document containing:

# Soul: [Role Name]

[First-person identity statement]

## Operating Principles

[Bullet points describing key behaviors]

## Communication Style

[How the agent communicates]

Soul content should be:

• First-person - Written from the agent's perspective ("I am...")
• Role-specific - Defines the unique character of this role
• Actionable - Describes concrete behaviors, not abstract qualities
• Paperclip-inspired - Clear ownership, decision discipline, communication standards

Adding or Modifying Presets

1. Create or edit the soul.md file in the appropriate directory
2. Update index.ts if adding a new preset (export the imported soul and add to AGENT_PRESETS array)
3. Run tests to verify: pnpm --filter @fusion/dashboard exec vitest run app/components/__tests__/agent-presets.test.ts

Preset vs Engine Templates

Dashboard presets are a UI-only concept that populates the New Agent dialog fields (name, icon, role, soul, instructionsText). They don't map to engine types.

Engine role prompts (in agentPrompts settings) define the actual agent behavior when executing tasks. These are separate from dashboard presets and live in project settings.

This separation means:

• Presets provide starting point personality and instructions for new agents
• Engine templates control actual task execution behavior
• An agent created from a preset can have its engine role prompt customized independently

Configurable Agent Prompts (agentPrompts)

agentPrompts project setting supports:

• templates[]: custom prompt templates by role
• roleAssignments: map role → template ID

When no assignment is configured, Fusion falls back to built-in defaults.

Fine-Grained Prompt Overrides (promptOverrides)

The Prompts section in the Settings modal provides a user-friendly interface for customizing specific segments of agent prompts. Unlike agentPrompts which replaces entire role templates, promptOverrides allows surgical customization of individual prompt sections.

Supported Override Keys

Key	Agent Role	Description
executor-welcome	executor	Introductory section for the executor agent
executor-guardrails	executor	Behavioral guardrails and constraints
executor-spawning	executor	Instructions for spawning child agents
executor-completion	executor	Completion criteria and signaling
triage-welcome	triage	Introductory section for the triage/specification agent
triage-context	triage	Context-gathering instructions
reviewer-verdict	reviewer	Verdict criteria and format
merger-conflicts	merger	Merge conflict resolution instructions
agent-generation-system	—	System prompt for AI-assisted agent specification generation
workflow-step-refine	—	System prompt for refining workflow step descriptions

How It Works

1. Navigate to Settings → Prompts in the dashboard
2. Each prompt shows its name, key, description, and current value
3. Edit the textarea to create a custom override
4. Click Reset to restore the built-in default

Clearing Overrides

To clear a specific override, click the Reset button in the UI. This sends null for that prompt key, deleting the override from settings and reverting to the built-in default.

Relationship with agentPrompts

• agentPrompts replaces entire role templates
• promptOverrides customizes individual segments within any template
• Both can be used together — promptOverrides applies to the segment even within a custom role template

Inter-Agent Messaging

Messaging is available in dashboard mailbox UI and CLI.

fn message inbox
fn message outbox
fn message send AGENT-001 "Please prioritize FN-420"
fn message read MSG-123
fn message delete MSG-123
fn agent mailbox AGENT-001

Agent Spawning

Executor sessions can spawn child agents through spawn_agent.

Behavior:

• Child agents run in separate worktrees
• Parent/child relationship is tracked
• Limits enforced:
  • maxSpawnedAgentsPerParent (default 5)
  • maxSpawnedAgentsGlobal (default 20)
• Child sessions terminate when parent task ends

Agent Delegation

Executor and heartbeat agents can discover and delegate work to other agents using two built-in tools:

• list_agents — List available agents with optional filters (role, state, includeEphemeral)
• delegate_task — Create a task and assign it to a specific agent; the task enters todo and the agent picks it up on their next heartbeat

Delegation is designed for cross-agent handoff (e.g., an executor handing off to a QA agent). For parallel worktree-based parallelization, use spawn_agent instead.

Heartbeat Monitoring and Trigger Scheduling

Fusion's HeartbeatTriggerScheduler supports five trigger types:

• timer — periodic wake based on heartbeat interval
• assignment — wake when task is assigned to agent
• on_demand — manual run trigger (POST /api/agents/:id/runs)
• automation — triggered by scheduled automation jobs
• routine — triggered by routine execution

All triggers respect per-agent maxConcurrentRuns and produce structured wake context metadata.

Control-Plane Lane (No Task Concurrency Gating)

Heartbeat runs from the Agents panel run on a separate control-plane lane that is independent of task execution concurrency limits. This ensures agent responsiveness is preserved even when task pipelines are saturated.

Key behaviors:

• Heartbeat runs (via POST /api/agents/:id/runs) execute without gating on maxConcurrent or in-progress task count
• The HeartbeatTriggerScheduler and HeartbeatMonitor components do not receive the task-lane semaphore
• Trigger scheduling remains responsive regardless of how busy the task pipeline is
• Active-run 409 conflict semantics still apply — a new heartbeat run is rejected if the agent already has an active run

Architectural boundary:

Component	Path	Concurrency
TriageProcessor	Task lane	Semaphore-gated
TaskExecutor	Task lane	Semaphore-gated
Scheduler	Task lane	Semaphore-gated
onMerge	Task lane	Semaphore-gated
HeartbeatMonitor	Utility/control plane	NOT semaphore-gated
HeartbeatTriggerScheduler	Utility/control plane	NOT semaphore-gated
CronRunner	Utility/control plane	NOT semaphore-gated

Dashboard Health Status

The dashboard displays agent health status in AgentsView, AgentListModal, and AgentDetailView using a centralized health evaluation utility (packages/dashboard/app/utils/agentHealth.ts).

Health Labels (Priority Order)

Label	Condition
Terminated	Agent state is "terminated"
Error	Agent state is "error" (uses lastError if available)
Paused	Agent state is "paused" (uses pauseReason if available)
Running	Agent state is "running" (task workers with active state also display "Running")
Disabled	runtimeConfig.enabled === false
Starting...	State is "active" with no lastHeartbeatAt
Idle	Non-active state with no lastHeartbeatAt
Healthy	Heartbeat is fresh within configured timeout
Unresponsive	Heartbeat exceeded configured timeout

Timeout Configuration

Health status uses a timeout-based evaluation:

1. If runtimeConfig.heartbeatTimeoutMs is set on the agent, use that value
2. Otherwise, use the default 60-second (60000ms) timeout

Key Behaviors

• Monitoring disabled: Agents with runtimeConfig.enabled === false display "Disabled" — they are NOT falsely labeled as "Unresponsive"
• Consistent across views: All dashboard surfaces use the same centralized utility, ensuring consistent health labels everywhere
• Auto-refresh: Health status is refreshed every 30 seconds while views are open to keep status current
• State-first evaluation: Terminal states (terminated, error, paused, running) take priority over timeout-based evaluation

Heartbeat Run Lifecycle

Agent runs have a defined lifecycle managed by AgentStore:

Run States

A heartbeat run can be in one of these states:

• active — Run is currently executing
• completed — Run finished successfully (via endHeartbeatRun(runId, "completed"))
• terminated — Run was stopped (via endHeartbeatRun(runId, "terminated"))
• failed — Run encountered an error

Run Lifecycle API

• startHeartbeatRun(agentId) — Creates a new run and persists it to structured storage
• endHeartbeatRun(runId, status) — Ends a run with terminal status, updates persisted state
• getActiveHeartbeatRun(agentId) — Returns the current active run (or null)
• getCompletedHeartbeatRuns(agentId) — Returns all terminal runs (newest first)
• saveRun(run) — Persists run to structured storage
• getRunDetail(agentId, runId) — Gets a specific run by ID

Active-Run Conflict Semantics

When an agent already has an active run, attempts to start a new run return 409 Conflict:

POST /api/agents/:id/runs → 409 { error: "Agent already has an active run", details: { runId } }

After a run is completed (or terminated), a new run can be started successfully:

POST /api/agents/:id/runs → 201 { id: "run-xxx", status: "active", ... }

Storage Architecture

Run records are stored in structured JSON files at .fusion/agents/{agentId}-runs/{runId}.json.

Heartbeat events are also appended to .fusion/agents/{agentId}-heartbeats.jsonl for legacy compatibility. The structured storage is the source of truth; heartbeat events provide a fallback for older run data.

Stopping Runs

Use POST /api/agents/:id/runs/stop to terminate an active run:

POST /api/agents/:id/runs/stop → 200 { ok: true, runId: "run-xxx" }

If there's no active run, returns { ok: true, message: "No active run" }.

Budget Governance

Per-agent token budget tracking controls costs and prevents runaway AI spending. Budget configuration is stored in runtimeConfig.budgetConfig.

Budget Configuration Fields

Field	Type	Description
tokenBudget	number	Maximum tokens allowed per budget period
usageThreshold	number (0-1)	Percentage threshold (0.8 = 80%) to trigger warning/warning state
budgetPeriod	"daily" | "weekly" | "monthly" | "total"	Reset interval for budget tracking
resetDay	number (0-6)	Day of week for weekly reset (0=Sunday)

Budget Status Fields

Field	Type	Description
isOverBudget	boolean	Budget limit exceeded
isOverThreshold	boolean	Usage exceeded warning threshold
periodStart	string	ISO timestamp when current period started
inputTokens	number	Tokens used in current period
outputTokens	number	Tokens generated in current period
totalTokens	number	Combined input + output tokens

Enforcement Behavior

Budget enforcement happens at multiple points:

• HeartbeatMonitor.executeHeartbeat() checks budget before creating sessions; skips when isOverBudget: true or isOverThreshold: true (for timer triggers)
• HeartbeatTriggerScheduler.onTimerTick() skips timer ticks when budget is exceeded

Agents can be paused by budget exhaustion. Timer-triggered heartbeats skip when over threshold to avoid runaway costs, but assignment-triggered and on-demand runs may still execute for responsiveness.

Budget API Endpoints

Method	Path	Description
GET	/api/agents/:id/budget	Get current budget status
POST	/api/agents/:id/budget/reset	Reset budget counters for current period

Agent Performance Ratings

Agent performance ratings allow users and agents to provide feedback that influences future behavior through system prompt injection.

Rating API Endpoints

Method	Path	Description
GET	/api/agents/:id/ratings	List all ratings for an agent
POST	/api/agents/:id/ratings	Submit a new rating
GET	/api/agents/:id/ratings/summary	Get aggregated rating summary
DELETE	/api/agents/:id/ratings/:ratingId	Delete a specific rating

Rating Structure

Ratings use a 1-5 scale:

Value	Meaning
1	Poor — consistently fails or produces low-quality output
2	Below average — often needs correction
3	Average — meets expectations with occasional issues
4	Good — reliable with minor improvements possible
5	Excellent — exceeds expectations consistently

Rating Summary

The summary endpoint returns aggregated statistics:

{
  "agentId": "AGENT-001",
  "averageRating": 4.2,
  "totalRatings": 15,
  "ratingDistribution": { "1": 0, "2": 1, "3": 2, "4": 8, "5": 4 },
  "trend": "improving"
}

The trend field indicates rating trajectory: "improving", "declining", or "stable".

Input Format

To submit a rating:

POST /api/agents/:id/ratings
{
  "rating": 4,
  "comment": "Agent completed the task efficiently with minimal corrections needed",
  "taskId": "FN-123"
}

Related Docs

• Workflow Steps
• Settings Reference
• Architecture