Delegate

Delegation Skill

Dispatch implementation tasks to subagents with proper context, worktree isolation, and TDD requirements. This skill follows a three-step flow: Prepare, Dispatch, Monitor.

Triggers

Activate this skill when:

• User runs delegate command
• Implementation plan is ready with extractable tasks
• User wants to parallelize work across subagents

Exception — oneshot workflows skip delegation entirely. The oneshot playbook runs an in-session TDD loop in the main agent's context, with no subagent dispatch or review phase. If workflowType === "oneshot", do not call this skill — see @skills/oneshot/SKILL.md for the lightweight path.

Core Principles

Fresh Context Per Task (MANDATORY)

Each subagent MUST start with a clean, self-contained context. As established in the Anthropic best practices for multi-agent coordination:

• No shared state assumptions. Every subagent prompt must contain the full task description, file paths, TDD requirements, and acceptance criteria. Never say "see the plan" or "as discussed earlier."
• No cross-agent references. Subagent A must not depend on output from Subagent B unless explicitly sequenced with a dependency edge in the plan.
• Isolated worktrees. Each subagent operates in its own git worktree. Parallel agents in the same worktree will corrupt branch state.

Rationalization patterns that violate this principle are catalogued in references/rationalization-refutation.md.

Delegation Modes

The default subagent mode dispatches each task using the runtime's spawn primitive: [sequential execution].

Model selection — a reasoning TIER, never a version

Use the recommendedModel from prepare_delegation task classifications when available. If no classification exists (e.g. fixer dispatch), omit model to inherit the session default.

recommendedModel is a reasoning tier (haiku | sonnet | opus), not a model version. The tier is derived from the task's riskTier via agents.tier-models (defaults low → haiku, medium → sonnet, high → opus; operator-overridable in .exarchos.yml, validated monotone so a higher risk tier can never resolve weaker).

Three rules follow, and they are the whole policy:

1. Never write a model version anywhere — not in a dispatch, an agent spec, a skill, or a prompt. No claude-*-YYYYMMDD, no -latest, no point releases. A version string pinned in content is a second model authority that outranks the operator's tier policy silently and rots on the next release. Pass the tier alias and let the harness resolve it against its own current catalog.
2. Strength follows RISK, not role. The agent choice selects the role (implementer / fixer / reviewer / scaffolder); the ladder selects the strength. An agent spec that pins a model id is a defect — that is why every shipped spec declares model: inherit.
3. If you need a version, read the catalog — do not recall one. Resolve the current tier→version mapping from the harness's own model list at dispatch time. Model recall from training data is stale by construction, and a guessed identifier fails closed at best and silently downgrades at worst.

unless otherwise specified means an explicit operator override in .exarchos.yml (agents.default-model, agents.models, agents.tier-models) — not a judgement call at dispatch time.

Pre-Dispatch Schema Discovery

Before dispatching, query decision runbooks to classify the work and select the right strategy:

1. Task complexity: exarchos_orchestrate({ action: "runbook", id: "task-classification" }) to get the cognitive complexity classification tree. Low-complexity tasks can use the scaffolder agent spec for faster execution.
2. Dispatch strategy: exarchos_orchestrate({ action: "runbook", id: "dispatch-decision" }) for dispatch strategy (parallel vs sequential, team sizing, isolation mode).

Step 1: Prepare

Use the prepare_delegation composite action to validate readiness in a single call. This replaces manual script invocations and individual checks.

Authoritative spec: the canonical list of preconditions, blockers, and arguments for prepare_delegation lives in the runtime — query it with exarchos_orchestrate({ action: "describe", actions: ["prepare_delegation"] }) if anything in this skill drifts from observed behavior. Treat the runtime describe output as the source of truth.

Step 0 — Pre-emit (required before prepare_delegation)

Before calling prepare_delegation, the workflow stream must contain a task.assigned event for each task. The readiness view counts these events to populate taskCount; without them, prepare_delegation returns { ready: false, blockers: ["no task.assigned events found ..."] }.

exarchos_event({
  action: "batch_append",
  stream: "<featureId>",
  events: tasks.map((t) => ({
    type: "task.assigned",
    data: { taskId: t.id, title: t.title, branch: t.branch },
  })),
})

Step 1 — Prepare (readiness check)

exarchos_orchestrate({
  action: "prepare_delegation",
  featureId: "<featureId>",
  planPath: "docs/specs/<the-decomposition-spec>.md",
  tasks: [{ id: "task-001", title: "...", modules: [...] }, ...]
})

Pass planPath. It points prepare_delegation at the decomposition markdown so it lifts each task's **Risk Tier:** / **Boundary Touching:** stamp automatically (deterministic parse — no hand-transcription). The stamp is what selects the per-task verification depth below; without planPath (and without an explicit riskTier/boundaryTouching on a task) every task falls back to a keyword/glob heuristic that under-provisions planner-high/boundary tasks (#1636). You may still set riskTier/boundaryTouching explicitly on a tasks[] entry to override the plan for one task; an explicit value always wins.

The composite action is read-only — it queries delegation readiness and assembles quality hints. It does not create worktrees and does not run npm install (its authoritative description is "Query delegation readiness and prepare quality hints for subagent dispatch"). Worktree materialization is the host's responsibility under native isolation, or an explicit setup_worktree call — which lays out the canonical .worktrees/<taskId>-<taskName> path. The action performs:

1. State validation — verifies workflow state is in delegate phase, plan exists, plan approved
2. Quality signal assembly — queries code_quality view; if gatePassRate < 0.80, returns quality hints to embed in prompts. Emits gate.executed('plan-coverage') on success (no pre-query needed)
3. Benchmark detection — sets verification.hasBenchmarks if any task has benchmark criteria
4. Readiness verdict — returns { ready: true, worktrees: [...], qualityHints: [...] } (the worktrees array reports the expected paths, not created ones) or { ready: false, reason: "..." }

If blocked: true with reason: "current-branch-protected": the response includes a hint field (e.g. "checkout the feature/phase branch before dispatching delegation"). Apply the hint, then re-call.

If ready: false: Stop. Report the reason to the user. Do not proceed.

If ready: true: Extract the worktrees paths and qualityHints for prompt construction.

Native isolation — verify worktrees before agents edit. Under native isolation (nativeIsolation: true), prepare_delegation returns ready: true even when the host has not yet materialized worktrees (worktrees.ready: 0), because isolation is the host's responsibility — readiness cannot be confirmed at prepare-time. When worktrees.expected > 0 and none are confirmed ready, the response carries a warning: "native isolation requested; N worktree(s) expected but 0 confirmed ready — verify the host materializes worktrees or dispatch may land in the shared checkout." Do not ignore it. After dispatching, and before any agent edits files, confirm each agent's working directory is under .worktrees/ (e.g. the agent's first reported pwd). If an agent is NOT in a worktree it has landed in the shared checkout — stop it, create the worktree manually with git worktree add -b <task-branch> .worktrees/<taskId>-<taskName> <integration-tip> (the same <taskId>-<taskName> layout setup_worktree uses, so a manually-created worktree is recognized without a second-path retry), redirect the agent to that path, and only then allow edits. Skipping this check risks silent shared-tree corruption across parallel agents.

Task Extraction

From the implementation plan, extract for each task:

• Full task description (paste inline; never reference external files)
• The **Risk Tier:** / **Boundary Touching:** stamps are lifted automatically when you pass planPath (above) — you do NOT need to re-transcribe them into tasks[]; pass them explicitly only to override the plan for a specific task
• Files to create/modify as worktree-relative paths rooted inside the worktree (e.g. src/foo.ts) — never an absolute parent-repo path, and never a .. sequence that escapes the worktree root. Either form resolves outside the agent's worktree cwd and silently writes into the main worktree. This is the platform-agnostic line of defense — it must hold on every runtime.
• Test file paths (worktree-relative) and expected test names
• Dependencies on other tasks (for sequencing)
• Property-based testing flag (testingStrategy.propertyTests)

For a complete worked example of this flow, see references/worked-example.md.

Step 2: Dispatch

Build subagent prompts using references/implementer-prompt.md as the template. Each prompt MUST include the full task context — this is the fresh-context principle in action.

Prompt Construction

Full prompt template (default):

For each task:

1. Fill the implementer prompt template with task-specific details
2. Set the Working Directory to the worktree path from Step 1
3. Include quality hints (if any) in the Quality Signals section
4. Include PBT section from references/pbt-patterns.md when propertyTests: true
5. Include testing patterns from references/testing-patterns.md

Tier-selected verification note — dispatch the rendered prompt

prepare_delegation resolves each task's risk tier — from the plan stamp when you passed planPath (the planner's authored value wins over the heuristic; a divergence is surfaced as a stamp: advisory in warnings). To keep a wave's payload economical it does not repeat a full rendered prompt on every task. Instead it returns, once, a shared implementerPromptTemplate carrying a verificationNote placeholder token, a deduped verificationNotes map (keyed by "<riskTier>|<boundaryTouching>"), and a per-task taskClassifications[i].verificationNoteKey. Reconstruct a task's tier-selected prompt by replacing that placeholder token in the template with the task's note — verificationNotes[taskClassifications[i].verificationNoteKey] — where a low-tier task's key selects a terse static-analysis steer and a high-tier task's selects the test-after + integration-suite rung. (Pass detail: true — alias outputFormat: "prompt-only" — to get the fully inline taskClassifications[i].implementerPrompt per task instead; it is lossless vs. the splice.)

Dispatch THAT reconstructed prompt — not the static agent default. The shipped agents/implementer.md bakes a fixed medium-tier note (a self-contained fallback for runtimes that pre-bind a named agent). Use it verbatim only when no classification exists (e.g. a fixer dispatch). Otherwise, the orchestrator's dispatch payload must be built from implementerPromptTemplate with the task's verificationNoteKey note spliced in, then fill its taskDescription / requirements / filePaths placeholders (the same template slots in references/implementer-prompt.md) with the task-specific context above. Dispatching the static default instead re-imposes medium-RGR ceremony on every task regardless of tier — the exact gap this seam closes. The tier is pure data from the classification stamp; no workflow-type branching is involved.

Decision Runbooks

For dispatch strategy decisions, query the decision runbook: exarchos_orchestrate({ action: "runbook", id: "dispatch-decision" })

This runbook provides structured criteria for parallel vs sequential dispatch, team sizing, and failure escalation.

For parallel grouping strategy and model selection, see references/parallel-strategy.md.

Verification Ownership Contract (ONE owner per claim)

Every verification claim has exactly one owner. Re-verifying a claim you do not own is duplicated work, not defense in depth — it inflates the wave's cost and hides which run is authoritative when the two disagree.

Two consequences bind the runbooks:

1. task_complete is the terminal step of the task-completion runbook. No blocking gate may run after it — a task that is marked complete has already passed every gate that could block it.
2. check_integration_suite is a wave-boundary backstop, not a per-task gate. It runs exactly once per wave, after the merges, matching its own action description. Per-task cascade risk is covered by the task's own scoped gates.

The lead's only independent verification is a spot check — reading the recorded evidence and, at most, sampling one claim it has concrete reason to doubt. A blanket re-run of the per-task chain is a contract violation.

Step 3: Monitor and Collect

Subagent Monitoring

Collect background task results using the runtime's result-collection primitive (this may be a poll/await per task or inline replies, depending on the runtime):

[task output is the assistant's next message]

After each subagent reports completion:

Runbook: For each completed task, execute the task-completion runbook: exarchos_orchestrate({ action: "runbook", id: "task-completion" }) Execute the returned steps in order. Stop on gate failure. If the runbook action is unavailable, use describe to retrieve gate schemas and run manually: exarchos_orchestrate({ action: "describe", actions: ["check_test_adequacy", "check_static_analysis", "task_complete"] })

1. Extract provenance from subagent report — parse the subagent's completion output and extract structured provenance fields (implements, tests, files). These fields are reported by the subagent following the Provenance Reporting section of the implementer prompt.

2. Verify worktree state — confirm each worktree has clean git status and passing tests

3. Run blocking gates — the task-completion runbook (referenced above) defines the exact gate sequence (test adequacy, static analysis, then task_complete). On any gate failure, keep the task in-progress and report findings. All gate handlers auto-emit gate.executed events, so manual exarchos_event calls are not needed.

4. Pass provenance in task completion — when marking a task complete, pass the extracted provenance fields in the result parameter so they flow into the task.completed event:

exarchos_orchestrate({
  action: "task_complete",
  taskId: "<taskId>",
  streamId: "<featureId>",
  result: {
    summary: "<task summary>",
    implements: ["DR-1", "DR-3"],
    tests: [{ name: "testName", file: "path/to/test.ts" }],
    files: ["path/to/impl.ts", "path/to/test.ts"]
  }
})

6. Update workflow state — set each passing tasks[].status to "complete" via exarchos_workflow update
7. Delegation completion gate (D4, advisory) — after ALL tasks pass, run an operational resilience check on the full branch diff before transitioning to review:

exarchos_orchestrate({
  action: "check_operational_resilience",
  featureId: "<featureId>",
  repoRoot: ".",
  baseBranch: "main"
})

This is advisory — findings are recorded for the convergence view but do not block the delegation→review transition. Include findings in the delegation summary for review-phase attention.

8. Schema sync — if any task modified API files (*Endpoints.cs, Models/*.cs), run npm run sync:schemas

Failure Recovery

When a task fails:

1. Read the failure output from the runtime's result-collection primitive ([task output is the assistant's next message])
2. Diagnose root cause — do NOT trust the implementer's self-assessment (see R3 adversarial posture)
3. Fix the task using the fixer flow below
4. Run the task-fix runbook gate chain after the fix completes

For the full recovery flow with a concrete example, see references/worked-example.md.

Fix Failed Tasks

Dispatch a fresh fixer agent using the runtime's native spawn primitive, carrying the full failure context and the original task description:

Execute each task sequentially in the current session, one at a time, against the prepared worktrees.

After fix completes, run the task-fix runbook gate chain: exarchos_orchestrate({ action: "runbook", id: "task-fix" }) If runbook unavailable, use describe to retrieve gate schemas: exarchos_orchestrate({ action: "describe", actions: ["check_test_adequacy", "check_static_analysis", "task_complete"] })

Fix Mode (--fixes)

Handles review failures instead of initial implementation. Uses references/fixer-prompt.md template with adversarial verification posture, dispatches fix tasks per issue, then re-invokes review to re-integrate fixes.

Arguments: --fixes <state-file-path> — state JSON containing review results in .reviews.<taskId>.specReview or .reviews.<taskId>.qualityReview.

For detailed fix-mode process, see references/fix-mode.md.

Deprecated: --pr-fixes has been superseded by /exarchos:shepherd. Use the shepherd skill for PR feedback workflows.

Context Compaction Recovery

If context compaction occurs during delegation:

1. Query workflow state: exarchos_workflow get with fields: ["tasks"]
2. Check active worktrees: ls .worktrees/ and verify branch state
3. Reconcile: exarchos_workflow reconcile replays the event stream and patches stale task state (CAS-protected)
4. Do NOT re-create branches or re-dispatch agents until confirmed lost

Worktree State Schema

Worktree entries are stored as worktrees["<wt-id>"] in workflow state. Each entry requires:

Either taskId or tasks (non-empty array) is required — at least one must be present.

Single-task example:

{ "branch": "feat/task-001", "taskId": "task-001", "status": "active" }

Multi-task example:

{ "branch": "feat/integration", "tasks": ["task-001", "task-002"], "status": "active" }

Phase Transitions and Guards

For the full transition table, consult @skills/checkpoint/references/phase-transitions.md.

Quick reference: The delegate → review transition requires guard all-tasks-complete — all tasks[].status must be "complete" in workflow state.

Before transitioning to review: You MUST first update all task statuses to "complete" via exarchos_workflow update with the tasks array. The phase transition will be rejected by the guard if any task is still pending/in_progress/failed. Update tasks first, then set the phase in a separate call.

Worktree-Bearing Tasks: Auto-Detour to merge-pending

When a task.completed event carries a worktree association (data.worktree or data.worktreePath), the HSM auto-transitions through feature/merge-pending before reaching review. The next_actions projection surfaces the merge verb (idempotency-keyed by ${streamId}:merge_orchestrate:${taskId}) so a runtime that consumes next_actions will dispatch the merge automatically.

Land it through serialize_merge. The integration branch is shared — sibling worktree merges within the same wave (or a concurrent operator) can race for it. serialize_merge is THE integration-merge path: it holds an optimistic per-integrationRef single-writer lease, then composes merge_orchestrate unchanged to do the local git merge with a recorded recovery-point SHA — see @skills/merge-orchestrator/SKILL.md. Do not dispatch raw merge_orchestrate to land onto the integration branch — a live foreign lease makes it fail closed (MERGE_LEASE_HELD, naming serialize_merge). Raw merge_orchestrate is for a non-integration merge (a private / scratch branch no sibling will touch) or a crash-resumed caller re-presenting its original lease.

The HSM exits merge-pending back to delegate once the merge terminates (completed / rolled-back / aborted), at which point delegate either re-enters merge-pending for the next worktree-bearing task or transitions on to review when all delegation is complete.

This detour is invisible to the delegation skill itself — the all-tasks-complete guard still gates the delegate → review transition. The merge-pending substate just sits between task completion and the next dispatch decision.

Task Status Values

Schema Discovery

Use exarchos_workflow({ action: "describe", actions: ["update", "init"] }) for parameter schemas and exarchos_workflow({ action: "describe", playbook: "feature" }) for phase transitions, guards, and playbook guidance. Use exarchos_orchestrate({ action: "describe", actions: ["check_test_adequacy", "task_complete"] }) for orchestrate action schemas.

When integration advances mid-wave

Runbook for recovering when a subagent worktree's branch has diverged from the integration branch. Triggered by the integration merge's ancestry preflight (run by the composed merge_orchestrate inside serialize_merge): the failure message links here verbatim and includes the manual git rebase command. Auto-rebase is not wired today — operators must drive recovery by hand.

Symptom

The merge-orchestrator reports an ancestry failure of the form:

source branch <feature-branch> is not a descendant of <integration-branch>.
Rebase manually with: git rebase <integration-branch> (run from the <feature-branch> worktree).
Runbook: content/delivery/skills/delegate/SKILL.md#when-integration-advances-mid-wave

This means the integration branch advanced (typically because an earlier worktree merge landed) while the failing worktree was still in flight. Fast-forward merge is no longer safe — the working branch must catch up first.

Why this happens

With the worktree base pinned to local HEAD (see prerequisite below), each subagent worktree is created at the integration branch's tip at dispatch time. When the orchestrator merges sibling worktrees serially, each merge moves the integration branch forward. A worktree that was dispatched against an older integration tip will fail the ancestry preflight when its turn comes.

This is expected behavior under the current single-writer merge contract — preflight is fail-only on purpose so the operator stays in control.

Recovery procedure

Before each step, verify you are in the main worktree (not the failing subagent worktree) and that git status is clean.

1. Capture the rollback SHA before doing anything destructive:

   git rev-parse <feature-branch> > /tmp/rollback.sha
   

   Keep this until the merge has been verified. If anything goes wrong, git reset --hard "$(cat /tmp/rollback.sha)" on the feature branch restores the pre-rebase state. The filename is intentionally branch-name-free so slash-delimited branches like feature/dr-6 don't break the path with embedded / characters.

2. Rebase the feature branch onto the current integration tip:

   cd <feature-worktree-path>
   git fetch origin
   git rebase <integration-branch>
   

   Resolve any conflicts that surface. The conflicts are real — they reflect genuine drift between the two branches, not preflight noise. Do not pass --strategy-option=theirs blindly; that drops the subagent's work.

3. Re-run the integration merge from the main worktree — through serialize_merge, which re-composes merge_orchestrate's ancestry preflight under the single-writer lease:

   exarchos_orchestrate({
     action: "serialize_merge",
     featureId: "<featureId>",
     integrationRef: "<integration-branch>",
     sourceBranch: "<feature-branch>",
     strategy: "squash",           // squash | rebase | merge
     taskId: "<taskId>",
     dryRun: false,                // REQUIRED to execute — the action DEFAULTS to dry-run
   })
   

   serialize_merge defaults to a dry-run (preflight only, no lease claimed): omit dryRun and it reports whether the merge would apply without mutating anything. Pass dryRun: false to actually claim the single-writer lease and perform the merge. The action is declared shared-mutating, so a read-only caller (a session without write capability) is denied even the apply path; in that case fall back to a local-git merge from the main worktree (git merge --squash <feature-branch> then commit) and record the equivalent merge state/events yourself, since that merge sits outside the serialized lease.

   The preflight should now pass. Proceed with the orchestrator's normal merge flow. (Re-run raw merge_orchestrate directly only for a non-integration merge, or as the crash-resumed caller re-presenting its original leaseOperationId.)

Rollback procedure

If the rebase produces conflicts you cannot resolve safely, or the merge still fails after rebase:

1. Reset the feature branch to the captured rollback SHA:

   cd <feature-worktree-path>
   git rebase --abort   # if mid-rebase
   git reset --hard "$(cat /tmp/rollback.sha)"
   

2. Mark the task failed in workflow state and dispatch a fixer (see the Failure Recovery section above). Do not delete the worktree — the fixer needs the original branch state to diagnose the conflict.

3. Record the incident by emitting a merge.aborted event with reason: "ancestry-rebase-conflict" and the failing branch's pre-rebase SHA so the convergence view captures the rollback.

Why no auto-rebase yet

Auto-rebase is not yet wired. Today the orchestrator stops at the ancestry preflight on purpose: a botched auto-rebase across diverged worktrees risks silently dropping subagent work, and the recovery path above is short enough that operator-driven rebase is preferable to clever-but-fragile automation.

Transition

After all tasks complete, auto-continue immediately (no user confirmation):

1. Verify all tasks[].status === "complete" in workflow state
2. Update state: exarchos_workflow update with phase: "review"
3. Invoke: [Invoke the exarchos:review skill with args: <plan-path>]

This is NOT a human checkpoint — the workflow continues autonomously.

References