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fusion/docs/settings-reference.md
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Settings Reference

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This guide documents Fusion settings from packages/core/src/types.ts.

Settings Scopes

Fusion uses a two-tier settings system:

  • Global settings (~/.pi/fusion/settings.json): user preferences shared across projects
  • Project settings (.fusion/config.json): execution/runtime behavior for one project

At runtime, settings are merged. Project settings override global settings when keys overlap.

Settings API Endpoints

Endpoint Purpose
GET /api/settings Get merged settings (global + project).
PUT /api/settings Update project settings only.
GET /api/settings/global Get global settings only.
PUT /api/settings/global Update global settings only.
GET /api/settings/scopes Get separated { global, project } view.

Global Settings

Defaults from DEFAULT_GLOBAL_SETTINGS; key scope from GLOBAL_SETTINGS_KEYS.

Setting Type Default Description
themeMode "dark" | "light" | "system" "dark" Dashboard theme mode.
colorTheme string "default" Dashboard color theme name.
defaultProvider string undefined Default AI provider.
defaultModelId string undefined Default AI model ID.
fallbackProvider string undefined Fallback provider when primary model is unavailable/rate-limited.
fallbackModelId string undefined Fallback model ID (must pair with fallbackProvider).
defaultThinkingLevel "off" | "minimal" | "low" | "medium" | "high" undefined Default reasoning effort level.
ntfyEnabled boolean false Enable ntfy push notifications.
ntfyTopic string undefined ntfy topic name.
ntfyEvents ("in-review" | "merged" | "failed" | "awaiting-approval" | "awaiting-user-review")[] ["in-review","merged","failed","awaiting-approval","awaiting-user-review"] Event types that trigger ntfy notifications.
ntfyDashboardHost string undefined Dashboard host used for deep-link URLs in notifications.
defaultProjectId string undefined Default project for multi-project commands.
openrouterModelSync boolean true Sync OpenRouter model catalog into pickers.
modelOnboardingComplete boolean undefined Whether model onboarding has been completed/dismissed.

Additional GlobalSettings fields

These exist in the GlobalSettings interface but are not listed in GLOBAL_SETTINGS_KEYS.

Setting Type Default Description
setupComplete boolean undefined Marks completion of first-run setup wizard state.
favoriteProviders string[] undefined Pinned provider names shown first in model selectors.
favoriteModels string[] undefined Pinned models in {provider}/{modelId} format.

Project Settings

Defaults from DEFAULT_PROJECT_SETTINGS; key scope from PROJECT_SETTINGS_KEYS.

Setting Type Default Description
globalPause boolean false Hard stop: terminate active engine sessions and pause scheduling.
enginePaused boolean false Soft pause: stop dispatching new work but allow active sessions to finish.
maxConcurrent number 2 Max concurrent task-lane AI agents (triage, executor, merge). Utility AI workflows run on a separate control-plane lane and are not gated by this limit.
maxWorktrees number 4 Max git worktrees.
pollIntervalMs number 15000 Scheduler poll interval (ms).
groupOverlappingFiles boolean true Serialize execution when file scopes overlap.
autoMerge boolean true Auto-finalize tasks from in-review.
mergeStrategy "direct" | "pull-request" "direct" Completion mode (local direct merge or PR-first).
worktreeInitCommand string undefined Shell command run after worktree creation.
testCommand string undefined Test command run at merge time (before buildCommand). When set, runs as a hard gate — non-zero exit blocks the merge. When not set, Fusion automatically infers a default command from the package manager lock file (pnpm test, yarn test, bun test, or npm test).
buildCommand string undefined Build command run at merge time (after testCommand). When set, runs as a hard gate — non-zero exit blocks the merge.
recycleWorktrees boolean false Reuse worktrees from a pool for faster startup.
worktreeNaming "random" | "task-id" | "task-title" "random" Naming mode for fresh worktree directories.
taskPrefix string "FN" Prefix for generated task IDs.
includeTaskIdInCommit boolean true Include task ID in commit message scope.
planningProvider string undefined AI provider for triage/spec generation.
planningModelId string undefined Model ID for triage/spec generation.
planningFallbackProvider string undefined Fallback provider for planning.
planningFallbackModelId string undefined Fallback model ID for planning.
validatorProvider string undefined AI provider for plan/code review.
validatorModelId string undefined Model ID for plan/code review.
validatorFallbackProvider string undefined Fallback provider for review.
validatorFallbackModelId string undefined Fallback model ID for review.
modelPresets array [] Reusable executor/validator model presets.
autoSelectModelPreset boolean false Auto-select presets by task size.
defaultPresetBySize object {} Mapping for S/M/L → preset ID.
autoResolveConflicts boolean true Enable automatic merge conflict pattern resolution.
smartConflictResolution boolean true Alias/preferred flag for smart merge conflict handling.
strictScopeEnforcement boolean false Block merges on out-of-scope file changes.
buildRetryCount number 0 Build retry attempts during merge.
buildTimeoutMs number 300000 Build timeout in ms (5 minutes).
requirePlanApproval boolean false Require manual approval before triage → todo.
reviewHandoffPolicy "disabled" | "comment-triggered" | "always" "disabled" Policy for agent-to-user review handoff.
showQuickChatFAB boolean false Show floating quick-chat button. Chat accessible from More menu when hidden.
experimentalFeatures Record<string, boolean> {} Project-scoped experimental feature toggles. Each key is a feature flag name, and the value indicates whether it is enabled. Features not present in this map are considered disabled. This allows teams to explicitly mark capabilities as experimental and toggle them on/off from the Settings dashboard.
taskStuckTimeoutMs number undefined Inactivity timeout for stuck-task recovery.
specStalenessEnabled boolean false Enable automatic re-triaging of tasks with stale specifications.
specStalenessMaxAgeMs number 21600000 Maximum age in ms before a specification (PROMPT.md) is considered stale and requires re-specification. Default: 6 hours.
autoUnpauseEnabled boolean true Auto-unpause after rate-limit-triggered pauses.
autoUnpauseBaseDelayMs number 300000 Base unpause retry delay in ms (5 min).
autoUnpauseMaxDelayMs number 3600000 Max unpause delay cap in ms (1 hour).
maxStuckKills number 6 Max stuck-task terminations before permanent failure.
maxSpawnedAgentsPerParent number 5 Max child agents per parent.
maxSpawnedAgentsGlobal number 20 Max total spawned agents in an executor instance.
missionStaleThresholdMs number 600000 Time in ms after which a mission in activating state is considered stale and eligible for self-healing recovery.
missionMaxTaskRetries number 3 Maximum automatic retry attempts for a failed mission-linked task before its feature is marked as blocked for manual intervention.
missionHealthCheckIntervalMs number 300000 Interval in ms between mission feature/task consistency checks. Set to 0 to disable periodic health checks.
maintenanceIntervalMs number 900000 Maintenance interval in ms (15 min).
autoUpdatePrStatus boolean false Auto-refresh PR status badges.
autoCreatePr boolean false Auto-create PRs for completed tasks.
autoBackupEnabled boolean false Enable scheduled DB backups.
autoBackupSchedule string "0 2 * * *" Backup cron schedule.
autoBackupRetention number 7 Number of backups to keep.
autoBackupDir string ".fusion/backups" Relative backup directory path.
autoSummarizeTitles boolean false Auto-generate titles for long untitled task descriptions.
titleSummarizerProvider string undefined AI provider for title summarization.
titleSummarizerModelId string undefined AI model ID for title summarization.
titleSummarizerFallbackProvider string undefined Fallback provider for title summarization.
titleSummarizerFallbackModelId string undefined Fallback model ID for title summarization.
tokenCap number undefined Proactive token threshold for context compaction.
insightExtractionEnabled boolean false Enable scheduled memory insight extraction.
insightExtractionSchedule string "0 2 * * *" Insight extraction cron schedule.
insightExtractionMinIntervalMs number 86400000 Minimum interval between insight extraction runs (24h).
memoryEnabled boolean true Enable project memory integration.
memoryBackendType string "file" Memory backend type: file, readonly, qmd, or custom backend. Unknown types are accepted and persisted verbatim; the system falls back to file at runtime.
runStepsInNewSessions boolean false Run each task step in a fresh agent session.
maxParallelSteps number 2 Max concurrent step sessions (14).
aiSessionTtlMs number 604800000 TTL in ms for persisted AI planning, subtask breakdown, and mission interview sessions. Valid range: 600000 (10 min) to 2592000000 (30 days).
aiSessionCleanupIntervalMs number 3600000 Interval in ms for scheduled AI session cleanup sweeps. Valid range: 60000 (1 min) to 86400000 (24 hours).
reflectionEnabled boolean false Enable/disable agent self-reflection workflows.
reflectionIntervalMs number 3600000 How often periodic reflections occur in milliseconds.
reflectionAfterTask boolean true When true, automatically trigger reflection after task completion.
agentPrompts object undefined Custom agent prompt templates + role assignments.
promptOverrides Record<string, string> undefined Fine-grained prompt segment overrides (e.g., {"executor-welcome": "..."}).

Additional ProjectSettings fields

These exist in ProjectSettings but are not part of PROJECT_SETTINGS_KEYS.

Setting Type Default Description
scripts Record<string, string> undefined Named script map used by script-mode workflow steps and setup hooks.
setupScript string undefined Named script key to run before task execution.

Model Selection Hierarchy

Triage/specification model

  1. Per-task planningModelProvider + planningModelId
  2. Global/project planningProvider + planningModelId
  3. Global defaultProvider + defaultModelId
  4. Automatic provider/model resolution

Executor model

  1. Per-task modelProvider + modelId
  2. Global defaultProvider + defaultModelId
  3. Automatic provider/model resolution

Reviewer model

  1. Per-task validatorModelProvider + validatorModelId
  2. Global/project validatorProvider + validatorModelId
  3. Global defaultProvider + defaultModelId
  4. Automatic provider/model resolution

Prompt Overrides

Fusion supports fine-grained customization of AI agent prompts through the promptOverrides setting. This enables surgical customization of specific prompt segments without replacing entire role prompts (which agentPrompts does).

Supported Prompt 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 into detailed agent prompts

How It Works

  1. Override Selection: When a prompt key is present with a non-empty value, that override replaces the default prompt segment.

  2. Fallback to Defaults: Missing or empty values fall back to the built-in default content.

  3. Cascade: agentPrompts provides full-role template customization, while promptOverrides provides segment-level customization. Both can be used together — promptOverrides applies to the segment even within a custom role template.

Clearing Overrides

To clear a specific override, set it to null:

{
  "promptOverrides": {
    "executor-welcome": null
  }
}

To clear all overrides, set promptOverrides to null:

{
  "promptOverrides": null
}

Configuration Example

{
  "settings": {
    "promptOverrides": {
      "executor-welcome": "Custom executor welcome message for this project...",
      "executor-guardrails": "## Custom Guardrails\n- Project-specific rules...",
      "triage-welcome": "Custom triage introduction..."
    }
  }
}

JSON Examples

1) Team baseline for reliable automation

{
  "settings": {
    "maxConcurrent": 3,
    "maxWorktrees": 6,
    "mergeStrategy": "direct",
    "autoResolveConflicts": true,
    "taskStuckTimeoutMs": 600000,
    "runStepsInNewSessions": true,
    "maxParallelSteps": 2
  }
}

2) Multi-model routing for plan/execute/review

{
  "settings": {
    "defaultProvider": "anthropic",
    "defaultModelId": "claude-sonnet-4-5",
    "planningProvider": "openai",
    "planningModelId": "gpt-4.1",
    "validatorProvider": "openai",
    "validatorModelId": "gpt-4o"
  }
}

3) Size-based preset auto-selection

{
  "settings": {
    "modelPresets": [
      {
        "id": "small-fast",
        "name": "Small / Fast",
        "executorProvider": "openai",
        "executorModelId": "gpt-4o-mini"
      },
      {
        "id": "large-deep",
        "name": "Large / Deep",
        "executorProvider": "anthropic",
        "executorModelId": "claude-sonnet-4-5",
        "validatorProvider": "openai",
        "validatorModelId": "gpt-4o"
      }
    ],
    "autoSelectModelPreset": true,
    "defaultPresetBySize": {
      "S": "small-fast",
      "L": "large-deep"
    }
  }
}

See also: Workflow Steps for how scripts and workflow model overrides are used.


Experimental Features

The experimentalFeatures setting provides a first-class mechanism for managing project-scoped experimental feature toggles. This allows teams to explicitly mark capabilities as experimental and toggle them on/off from a dedicated section in the Settings dashboard.

How It Works

  1. Feature Registry: Features are stored as key-value pairs where keys are feature names and values indicate enabled/disabled state.

  2. Default Behavior: Features not present in the map are considered disabled (fallback to false).

  3. UI Integration: The Experimental Features section in Settings provides toggle controls for each configured feature.

  4. Consumption: Engine code can read experimentalFeatures[key] to check if a feature is enabled.

Example JSON Shape

{
  "settings": {
    "experimentalFeatures": {
      "my-new-feature": true,
      "another-experiment": false
    }
  }
}

Dashboard UI

The Experimental Features section in Settings shows:

  • Feature name and enabled/disabled toggle for each configured feature
  • Project scope indicator (features are project-specific, not global)
  • Description explaining the purpose of experimental features

Background Memory Summarization & Audit

Fusion can automatically extract insights from project memory and prune transient content on a schedule. This feature is disabled by default and can be enabled via settings.

How It Works

  1. Scheduled Extraction: When insightExtractionEnabled is true, a background automation runs on the configured insightExtractionSchedule (default: daily at 2 AM).

  2. AI-Powered Analysis: The automation uses an AI agent to read .fusion/memory.md and .fusion/memory-insights.md, extract new insights, and produce a pruned working memory candidate.

  3. Insight Merging: New insights are automatically merged into .fusion/memory-insights.md under the appropriate category (Patterns, Principles, Conventions, Pitfalls, Context). Duplicates are skipped.

  4. Memory Pruning: The AI agent also produces a pruned version of working memory containing only durable items:

    • Preserved: Architecture, Conventions, Pitfalls, Context sections with durable content
    • Pruned: Task-specific notes, one-time observations, outdated entries
  5. Audit Report: After each extraction run, a .fusion/memory-audit.md file is generated with:

    • Working memory status (presence, size, sections)
    • Insights memory status (insight counts by category)
    • Last extraction results (success/failure, insight count, duplicates skipped)
    • Pruning outcome (applied/skipped, size delta, reason)
    • Health status (healthy/warning/issues)
    • Individual audit checks

Output Files

File Description
.fusion/memory.md Working memory (updated when pruning is applied and validated)
.fusion/memory-insights.md Long-term insights distilled from working memory
.fusion/memory-audit.md Human-readable audit report after each extraction

Settings Interaction

Setting Effect
insightExtractionEnabled Enables/disables the automation
insightExtractionSchedule Cron expression for when extraction runs (default: "0 2 * * *" = daily at 2 AM)
insightExtractionMinIntervalMs Minimum time between extractions (default: 24 hours)

Safety Guarantees

  • Pruning validation: Before pruning is applied, the candidate is validated to ensure it preserves at least 2 of 3 required sections (Architecture, Conventions, Pitfalls). Invalid candidates are safely ignored.
  • Graceful failures: Malformed AI output does not destroy existing memory. Prior files are preserved.
  • Isolated processing: Post-run callback errors are logged but do not flip successful runs to failed.
  • Startup sync: Automation schedule is synchronized before the cron runner starts, preventing stale config races.
  • Non-destructive by default: If the AI produces no prune candidate or validation fails, working memory remains unchanged.

Configuration Example

{
  "settings": {
    "insightExtractionEnabled": true,
    "insightExtractionSchedule": "0 2 * * *",
    "insightExtractionMinIntervalMs": 86400000
  }
}

Cron Expression Format

Standard cron format: minute hour day-of-month month day-of-week

Expression Meaning
0 2 * * * Daily at 2:00 AM (default)
0 */6 * * * Every 6 hours
0 9 * * 1 Weekly on Monday at 9:00 AM