Shepherd

Shepherd Skill

VCS Provider

This skill uses VCS operations through Exarchos MCP actions (check_ci, list_prs, merge_pr, get_pr_comments, add_pr_comment, etc.). These actions automatically detect and route to the correct VCS provider (GitHub, GitLab, Azure DevOps). No gh/glab/az commands needed — the MCP server handles provider dispatch.

The merge_pr invoked here is the remote PR merge primitive (synthesize-phase). It is distinct from the integration merge run during the upstream merge-pending substate — there, serialize_merge (@skills/merge-orchestrator/SKILL.md) is the integration-merge path: it holds a single-writer lease and composes the local git merge (raw merge_orchestrate is that composed executor / the non-integration path). This skill never invokes serialize_merge or merge_orchestrate.

Iterative loop that shepherds published PRs through CI checks and code reviews to merge readiness. Uses the assess_stack composite action for all PR health checks, fixing failures and addressing feedback until the stack is green.

Note: Shepherd is not a separate HSM phase. It operates as a loop within the synthesize phase. The workflow phase remains synthesize throughout the shepherd iteration cycle. Events (shepherd.iteration, ci.status) and the shepherd_status view track loop progress without requiring a phase transition.

Position in workflow:

synthesize → shepherd (assess → fix → resubmit → loop) → cleanup
              ^^^^^^^^^ runs within synthesize phase

Default Objective

By default, shepherd seeks to address every piece of feedback on the PR — appending "address all feedback" to the invocation is redundant, because it is the default, not an opt-in. Each iteration drives toward zero outstanding items across all three feedback channels:

• CI / checks — every failing or pending check is fixed or resolved.
• Formal reviews — every CHANGES_REQUESTED review is addressed.
• Inline comments — every inline review comment (human, CodeRabbit, Sentry, bots) gets a fix and/or a reply, regardless of severity. A minor or nit-level comment is still feedback: address it, or reply explaining why it is intentionally declined. The goal is that a human scanning the PR sees every thread has a response.

assess_stack is advisory: its computeRecommendation only forces fix-and-resubmit on critical/major items, so it can return request-approval while minor comment-reply items remain. Do not treat that as license to skip them — only request approval once every comment-reply action item is addressed (fix or reply). "Address all feedback" is the standing default.

Pipeline Hygiene

When the pipeline accumulates stale workflows (inactive > 7 days), run @skills/prune/SKILL.md to bulk-cancel abandoned workflows before starting a new shepherd cycle. Discover the stale set with exarchos:exarchos_view({ action: "pipeline", scope: "all" }) — the default view is repo-scoped to the caller's repo and hides legacy rows (workflows started before repo identity was recorded), which are exactly the stale ones this cleanup targets. Safeguards skip workflows with open PRs or recent commits, so active shepherd targets are never touched. A clean pipeline makes shepherd iteration reporting easier to read and reduces noise in the stale-count view.

Triggers

Activate when:

• User runs shepherd or says "shepherd", "tend PRs", "check CI"
• PRs are published and need monitoring through the CI/review gauntlet
• After synthesize completes and PRs are enqueued

Prerequisites

• Active workflow with PRs published (PR URLs in synthesis.prUrl or artifacts.pr)
• PRs created and pushed (create_pr already ran)
• Exarchos MCP tools available for VCS operations

Process

Runbook: Each shepherd iteration follows the shepherd-iteration runbook: exarchos_orchestrate({ action: "runbook", id: "shepherd-iteration" }) If runbook unavailable, use describe to retrieve action schemas: exarchos_orchestrate({ action: "describe", actions: ["assess_stack"] })

The shepherd loop repeats until all PRs are healthy or escalation criteria are met. Default: 5 iterations.

Step 0 — Surface Quality Signals

At the start of each iteration, query quality hints to inform the assessment:

exarchos:exarchos_view({ action: "code_quality", workflowId: "<featureId>" })

• If regressions is non-empty, include regression context in the status report
• If any hint has confidenceLevel: 'actionable', surface the suggestedAction in the iteration summary
• If gatePassRate < 0.80 for any skill, flag degrading quality trends

This step ensures the agent acts on accumulated quality intelligence before polling individual PRs.

Step 1 — Assess

Invoke the assess_stack composite action to check all PR dimensions at once:

exarchos:exarchos_orchestrate({
  action: "assess_stack",
  featureId: "<id>",
  prNumbers: [123, 124, 125]
})

The composite action internally handles:

• CI status checking for all PRs
• Formal review status (APPROVED / CHANGES_REQUESTED)
• Inline review comment polling and thread resolution (Sentry, CodeRabbit, humans)
• Stack health verification
• Event emission: gate.executed events per CI check (feeds CodeQualityView) and ci.status events per PR (feeds ShepherdStatusView). See references/gate-event-emission.md for the event format.

Review the returned actionItems and recommendation:

Step 2 — Fix

Anchor every change to the invariant catalog (evaluation-time Constraints). Before composing any code fix, load .exarchos/invariants.md (entries marked cost-of-load: always-load) and surface a Constraints section naming the invariants the fix must preserve, then probe each proposed change against them. This is the shepherd evaluation-time equivalent of ideate's Phase 0 and uses the same single shared source of truth for the selection rules and catalog-registration gating: @skills/ideate/references/constraint-anchoring.md. Catalog-registration gated: when no catalog is registered under .exarchos.yml: invariants.catalogs, surface no Constraints section and fix directly. This makes "when evaluating changes, apply .exarchos/invariants.md" the default — there is no need to request it per invocation.

Before iterating over individual action items, classify them so the loop knows which to fix inline vs. delegate. Call classify_review_items on the assessment's actionItems (the comment-reply subset is what the classifier groups by file; CI-fix and review-address items are passed through unchanged):

exarchos:exarchos_orchestrate({
  action: "classify_review_items",
  featureId: "<id>",
  actionItems: <actionItems from assess_stack>
})

The result returns groups: ClassificationGroup[] with a recommendation per group: direct (handle inline), delegate-fixer (spawn the fixer subagent for batched/HIGH-severity work), or delegate-scaffolder (cheap subagent for doc nits). Iterate the groups in order, applying per-group strategy, then consult references/fix-strategies.md for detailed per-issue-type instructions.

Remediation event protocol (FLYWHEEL):

1. BEFORE applying a fix, emit remediation.attempted:

   exarchos:exarchos_event({
     action: "append",
     stream: "<featureId>",
     event: {
       type: "remediation.attempted",
       data: { taskId: "<taskId>", skill: "shepherd", gateName: "<failing-gate>", attemptNumber: <N>, strategy: "direct-fix" }
     }
   })
   

2. Apply the fix (CI failure, review comment response, stack restack).

3. AFTER the next assess confirms the fix resolved the gate, emit remediation.succeeded:

   exarchos:exarchos_event({
     action: "append",
     stream: "<featureId>",
     event: {
       type: "remediation.succeeded",
       data: { taskId: "<taskId>", skill: "shepherd", gateName: "<gate>", totalAttempts: <N>, finalStrategy: "direct-fix" }
     }
   })
   

These events feed selfCorrectionRate and avgRemediationAttempts metrics in CodeQualityView.

Action item types:

Every inline review comment must get a reply. The goal is that a human scanning the PR sees every thread has a response.

Step 3 — Resubmit

After fixes are applied, resubmit the stack:

git push --force-with-lease

Re-enable auto-merge if needed:

exarchos_orchestrate({ action: "merge_pr", prId: "<number>", strategy: "squash" })

Return to Step 1 for the next iteration. Track iteration count against the limit (default 5). If the limit is reached without reaching request-approval, escalate per references/escalation-criteria.md.

Step 4 — Request Approval

When assess_stack returns recommendation: 'request-approval' (all checks green, all comments addressed):

Guard: Confirm there are no remaining comment-reply action items before requesting approval. Per the Default Objective, every inline comment — including minor/nit-level — must be addressed first. If any remain, return to Step 2 instead of requesting approval.

Invariant-conformance pointer (catalog-registration gated, before merge): When a catalog is registered under .exarchos.yml: invariants.catalogs, run the review-phase-scoped check_invariant_conformance action over the PR diff before requesting approval / merge, so the merge-gate read of the architectural invariants matches the diff that is about to land. This is a pointer/affordance, not a hard gate — the action is non-blocking (gate: { blocking: false }); it surfaces conformance findings to fold into the review verdict, it does not stop the merge. It is not a design-time Constraints section (shepherd runs at synthesize/merge, not design-time) — Step 2's Constraints anchoring covers fix composition; this pointer covers the diff-vs-invariants read at the review/merge gate. When no catalog is registered, skip this step.

exarchos:exarchos_orchestrate({
  action: "check_invariant_conformance",
  featureId: "<id>",
  phase: "review",
  diff: "<PR diff>"
})

1. Request review via GitHub MCP:

   mcp__plugin_github_github__update_pull_request({
     owner: "<owner>", repo: "<repo>", pullNumber: <number>,
     reviewers: ["<approver>"]
   })
   

   Fallback (if MCP token lacks write scope): gh pr edit <number> --add-reviewer <approver>

2. Report to user:

   ## Ready for Approval
   
   All CI checks pass. All review comments addressed.
   Approval requested from: <approvers>
   
   PRs:
   - #123: <url>
   - #124: <url>
   
   Run `cleanup` after merge completes.
   

State Management

Track shepherd progress via workflow state:

Initialize:

exarchos:exarchos_workflow({
  action: "update",
  featureId: "<id>",
  updates: {
    "shepherd": {
      "startedAt": "<ISO8601>",
      "currentIteration": 0,
      "maxIterations": 5,
      "approvalRequested": false
    }
  }
})

After each iteration: Update currentIteration, record assessment summary and actions taken. On approval: set approvalRequested: true with timestamp and approver list.

Phase Transitions and Guards

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

The shepherd skill operates within the synthesize phase and does not drive phase transitions directly.

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_event({ action: "describe", eventTypes: ["shepherd.iteration", "ci.status", "remediation.attempted"] }) for event data schemas before emitting events.

Event Emission

Before emitting any shepherd events, consult references/shepherd-event-schemas.md for full Zod schemas, type constraints, and example payloads. Use exarchos_event({ action: "describe", eventTypes: ["shepherd.iteration", "ci.status"] }) to discover required fields at runtime.

Domain Knowledge

Consult these references for detailed guidance:

• references/fix-strategies.md — Fix approaches per issue type, response templates, remediation event emission details
• references/escalation-criteria.md — When to stop iterating and escalate to the user
• references/gate-event-emission.md — Event format for gate.executed (now emitted by assess_stack)
• references/shepherd-event-schemas.md — Full Zod-aligned schemas for all four shepherd lifecycle events

Decision Runbooks

When iteration limits are reached or CI repeatedly fails, consult the escalation runbook: exarchos_orchestrate({ action: "runbook", id: "shepherd-escalation" })

This runbook provides structured criteria for deciding whether to keep iterating, escalate to the user, or abort the shepherd loop based on iteration count, CI stability, and review status.

Anti-Patterns

Transition

After approval is granted and PRs merge, run cleanup to resolve the workflow to completed state.