shepherd

name	shepherd
description	Shepherd PRs through CI and reviews to merge readiness. Operates as an iteration loop within the synthesize phase (not a separate HSM phase). Uses assess_stack to check PR health, fix failures, and request approval. Triggers: 'shepherd', 'tend PRs', 'check CI', or /shepherd.
metadata	{"author":"exarchos","version":"2.0.0","mcp-server":"exarchos","category":"workflow","phase-affinity":"synthesize"}

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:

Recommendation	Action
request-approval	Skip to Step 4 only if every comment-reply item is addressed. If any inline comment is still unaddressed, treat as fix-and-resubmit and address it first (see Default Objective).
fix-and-resubmit	Proceed to Step 2
wait	Inform user, pause, re-assess after delay
escalate	See references/escalation-criteria.md

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 devCatalog gating: @skills/ideate/references/constraint-anchoring.md. devCatalog-gated: when .exarchos.yml: invariants.devCatalog: enabled is unset or disabled, 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:

Type	Strategy
ci-fix	Read logs, reproduce locally, fix, commit to stack branch
comment-reply	Use actionItem.reviewer, normalizedSeverity, file, line, and raw (full original comment) to compose a response. Provider adapters under servers/exarchos-mcp/src/review/providers/ populate the input fields — no manual tier parsing needed. Posting: both PR-level summary comments and per-thread inline replies use the provider-agnostic add_pr_comment orchestrate action — pass a threadId to route a reply into a specific inline thread (via VcsProvider.addReply). Inline thread replies are supported on GitHub; GitLab and Azure DevOps return an explicit "not yet supported" capability signal.
review-address	Fix code for CHANGES_REQUESTED, reply to each thread
restack	Run git rebase origin/<base>, verify with exarchos_orchestrate({ action: "list_prs" })
escalate	Consult references/escalation-criteria.md

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 (devCatalog-gated, before merge): When .exarchos.yml: invariants.devCatalog: enabled, 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 the flag is unset or disabled, 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.

Event	When	Purpose
shepherd.started	On skill start (emitted by assess_stack)	Audit trail
shepherd.iteration	After each assess cycle	Track progress
gate.executed	Per CI check (emitted by assess_stack)	CodeQualityView -- gate pass rates
ci.status	Per CI check result	ShepherdStatusView -- PR health tracking
remediation.attempted	Before applying a fix	selfCorrectionRate metric
remediation.succeeded	After fix confirmed	avgRemediationAttempts metric
shepherd.approval_requested	On requesting review	Audit trail
shepherd.completed	On merge detected (emitted by assess_stack)	Audit trail

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

Don't	Do Instead
Poll CI/reviews directly	Use assess_stack composite action
Force-merge with failing CI	Fix the failures first
Ignore inline comments	Address every thread with a reply
Skip minor/nit comments because assess_stack said request-approval	Address every comment-reply item first — the recommendation is advisory (see Default Objective)
Compose fixes without checking invariants	Anchor each change to .exarchos/invariants.md (Step 2, devCatalog-gated)
Merge without a diff-vs-invariants read when devCatalog is on	Run check_invariant_conformance over the PR diff before approval/merge (Step 4 pointer, devCatalog-gated, non-blocking)
Loop indefinitely	Respect iteration limits, escalate
Skip remediation events	Emit remediation.attempted / remediation.succeeded for every fix
Push directly to main	All fixes go through stack branches

Transition

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