Merge Orchestrator Skill

Local Git, Not Remote VCS

This skill performs local
git merge
of a subagent's worktree branch into the integration branch, recording a rollback SHA so a

git reset --hard

can undo the merge on any failure. It does not call the VCS provider (GitHub / GitLab / Azure DevOps) and does not require a PR id. For remote PR merging during the synthesize phase, see

@skills/synthesis/SKILL.md

(

merge_pr

action).

The mental model and the rationale for why these are two separate concerns are documented in

references/local-git-semantics.md

Overview

Closes the loop between

/delegate

(which spawns subagents into worktrees) and the integration branch that needs their work. After a delegated task completes inside a worktree, this skill:

Composes preflight guards (ancestry, current-branch protection, main-worktree assertion, working-tree drift).
Records pre-merge
```
HEAD
```
of the integration branch as a rollback anchor.
Performs a local
```
git merge
```
of the source (subagent) branch into the target (integration) branch.
On any failure, runs
```
git reset --hard <rollbackSha>
```
and surfaces a categorized failure reason.
Emits dedicated event types so the merge timeline is reconstructable from the event log alone.

Resumable: terminal phases (

completed

rolled-back

aborted

) short-circuit on re-entry without re-emitting events. Idempotent: re-dispatch with the same

taskId

collapses via the

next_actions

idempotency key.

Triggers

Activate this skill when:

The HSM is parked in
```
feature/merge-pending
```
(entry guard fires when the most recent
```
task.completed
```
carries a worktree association).

The

next_actions

envelope surfaces a

merge_orchestrate

verb with idempotency key

${streamId}:merge_orchestrate:${taskId}

The user runs

exarchos merge-orchestrate ...

(CLI) or invokes

mcp__exarchos__exarchos_orchestrate({ action: "merge_orchestrate", ... })

directly.

Do not activate this skill:

During the synthesize phase to merge a remote PR — that is
```
merge_pr
```
.
When the workflow's
```
mergeOrchestrator.phase
```
is already terminal — the resume short-circuit runs but no fresh dispatch is needed.

Process

Schema: discover the action's argument schema with
mcp__exarchos__exarchos_orchestrate({ action: "describe", actions: ["merge_orchestrate"] })
. Strategy is required (no schema-level default) — pick
squash
/
merge
/
rebase
deliberately.

Step 1: Pick the merge strategy

Strategy	Local git operation	When to choose
`merge`	`git merge --no-ff --no-edit <source>` — explicit merge commit	Preserves the subagent's commit history with a visible merge boundary.
`squash`	`git merge --squash <source>` then `git commit` — single squash commit on target	Subagent commit history is noise; one logical change should land as one commit.
`rebase`	rebases an ephemeral copy of source onto target then ff-merges target — linear history	No merge commit; integration branch stays linear. The original source ref is preserved (the rebase runs on a temporary branch that is deleted afterward), so an executor rollback only needs to reset target.

Strategy is required at the schema layer (#1127 collision check, #1109 §2 user-visible parity). There is no implicit default — operator intent is always explicit in the event log.

Step 2: Invoke

Via MCP:

typescript

mcp__exarchos__exarchos_orchestrate({
  action: "merge_orchestrate",
  featureId: "<id>",
  sourceBranch: "<subagent-branch>",
  targetBranch: "<integration-branch>",
  taskId: "<task-id>",        // present when auto-dispatched from next_actions
  strategy: "squash",          // required
  dryRun: false,               // optional — preflight only, no executor invocation
  resume: false,               // optional — short-circuit on terminal phases
})

Via CLI:

bash

exarchos merge-orchestrate \
  --feature-id <id> \
  --source-branch <subagent-branch> \
  --target-branch <integration-branch> \
  --task-id <task-id> \
  --strategy squash
  # add --dry-run for preflight-only, --resume for terminal-phase short-circuit

CLI exit codes: 0 = success, 1 = invalid input, 2 = merge failed (preflight blocked or rollback executed), 3 = uncaught exception.

Step 3: Interpret the result

The handler returns a

ToolResult

whose

data.phase

discriminates the outcome:

`phase`	Meaning	Operator action
`completed`	Local merge landed; `mergeSha` is the new HEAD of target.	None — workflow exits `merge-pending` back to `delegate` (HSM) and continues.
`aborted`	Preflight failed; no merge attempted. `data.preflight` carries the structured guard sub-results.	Inspect `preflight.ancestry / worktree / currentBranchProtection / drift` to identify which guard failed. Resolve the underlying condition (e.g., commit/stash drift, switch off a protected branch) and re-dispatch.
`rolled-back`	Merge was attempted, failed ( `reason: 'merge-failed' / 'verification-failed' / 'timeout'` ), and `git reset --hard <rollbackSha>` ran. The integration branch is restored.	Inspect `data.reason` . If `data.rollbackError` is also present, the reset itself failed — the working tree is stranded and requires operator intervention.

For the full recovery flow per outcome, see

references/recovery-runbook.md

Step 4: Confirm event emissions

Three events are emitted directly to the workflow's event stream (stream id =

featureId

) — not wrapped in

gate.executed

Event type	When	Carries
`merge.preflight`	Always (after preflight runs, before any merge attempt)	Full structured guard sub-results + `failureReasons` if `passed: false`
`merge.executed`	On successful local merge	`mergeSha` , `rollbackSha` , `taskId` , source/target branches
`merge.rollback`	On post-merge failure followed by reset	`rollbackSha` , `reason` , `taskId` , source/target branches

These events are auto-emitted by the handler — do not manually append them via

mcp__exarchos__exarchos_event

during normal operation. Manual emission is only sanctioned during the documented manual-recovery flow in

recovery-runbook.md

when a merge has been completed out-of-band (e.g., conflict resolution) and the event log must be brought back in sync — follow that runbook's event-first sequencing.

Discover the event payload schemas via

mcp__exarchos__exarchos_event({ action: "describe", eventTypes: ["merge.preflight", "merge.executed", "merge.rollback"] })

Disambiguation:

merge_orchestrate

merge_pr

Two related actions, two distinct concerns:

Aspect	`merge_orchestrate` (this skill)	`merge_pr` (synthesis skill)
Layer	Local SDLC handoff	Remote PR primitive
Phase affinity	`merge-pending` (between delegate and review)	`synthesize`
What it merges	A subagent worktree branch into the integration branch	A user-facing PR via the VCS provider API
Identifier required	`sourceBranch` + `targetBranch`	`prId`
Underlying operation	`git merge` (local)	`provider.mergePr()` (remote API)
Rollback	`git reset --hard <rollbackSha>` (real, undoes the merge)	None — the VCS provider owns merge state
Events	`merge.preflight` / `merge.executed` / `merge.rollback`	`pr.merged`

If you reach for

merge_orchestrate

thinking "I want to merge a PR," you want

merge_pr

instead.

Resume Semantics

When invoked with

resume: true

, the handler reads existing

mergeOrchestrator

state. Terminal phases (

completed

rolled-back

aborted

, members of

EXCLUDED_MERGE_PHASES

) short-circuit and return the recorded result with no new events and no executor call. Non-terminal phases (

pending

executing

) fall through to a fresh preflight + executor run, which is safe because the underlying git operations are idempotent on already-merged branches.

When invoked without

resume

, prior state is deliberately ignored — fresh-dispatch semantics.

Dry-Run

dryRun: true

runs preflight, emits

merge.preflight

, and short-circuits before the executor runs and before any state persistence. Returns

{ dryRun: true, preflight, phase: 'pending' | 'aborted' }

. Useful for CI integrations that check merge readiness before the merge window opens.

Anti-Patterns

Don't	Do Instead
Use this skill to merge a remote PR	Use `merge_pr` in the synthesize phase
Manually emit `merge.preflight` / `merge.executed` / `merge.rollback` in normal flow	Let the handler auto-emit; manual emission causes duplicates (one exception: documented manual-recovery flow in `recovery-runbook.md` )
Wrap merge events under `gate.executed`	Direct stream append with the dedicated event type — these are state transitions, not gate executions
Re-dispatch after a `rolled-back` outcome without inspecting the reason	Read `data.reason` and `data.rollbackError` ; address the root cause first
Omit `--strategy` / `strategy:` field expecting a default	Strategy is required; supply `squash` / `merge` / `rebase` explicitly
Invoke from a subagent worktree	Preflight refuses (main-worktree assertion); invoke from the main worktree

Phase Transitions and Guards

For the full transition table, consult

@skills/workflow-state/references/phase-transitions.md

Quick reference:

delegate

→

merge-pending

requires guard

merge-pending-entry

— fires when the most recent

task.completed

carries a worktree association AND

mergeOrchestrator.phase

is not in

EXCLUDED_MERGE_PHASES

merge-pending

→

delegate

requires guard

merge-pending-exit

— fires when

mergeOrchestrator.phase

enters a terminal value (

completed

rolled-back

aborted

The HSM exits

merge-pending

back to

delegate

regardless of merge outcome —

delegate

then re-evaluates whether more worktree-bearing tasks remain and either re-enters

merge-pending

for the next, or transitions on to

review

when all delegation is complete.

Schema Discovery

For the argument schema, call

mcp__exarchos__exarchos_orchestrate({ action: "describe", actions: ["merge_orchestrate"] })

. The full feature-workflow phase playbook (which includes

merge-pending

) is available via

mcp__exarchos__exarchos_workflow({ action: "describe", playbook: "feature" })

. Event payload shapes come from

mcp__exarchos__exarchos_event({ action: "describe", eventTypes: ["merge.preflight", "merge.executed", "merge.rollback"] })

Completion Criteria

Preflight result
```
passed: true
```
(or operator has decided to proceed despite a documented preflight gap)
```
mergeOrchestrator.phase === 'completed'
```
in workflow state
```
merge.executed
```
event present in the stream with the recorded
```
mergeSha
```
and
```
rollbackSha
```
HSM has exited
```
merge-pending
```
back to
```
delegate
```
Integration branch's HEAD matches the recorded
```
mergeSha
```

If any criterion fails, consult

references/recovery-runbook.md

before re-dispatching.

merge-orchestrator

NPX Install

Tags

SKILL.md Content

Merge Orchestrator Skill

Local Git, Not Remote VCS

Overview

Triggers

Process

Step 1: Pick the merge strategy

Step 2: Invoke

Step 3: Interpret the result

Step 4: Confirm event emissions

Disambiguation:
`merge_orchestrate`
vs
`merge_pr`

Resume Semantics

Dry-Run

Anti-Patterns

Phase Transitions and Guards

Schema Discovery

Completion Criteria

merge-orchestrator

NPX Install

Tags

SKILL.md Content

Merge Orchestrator Skill

Local Git, Not Remote VCS

Overview

Triggers

Process

Step 1: Pick the merge strategy

Step 2: Invoke

Step 3: Interpret the result

Step 4: Confirm event emissions

Disambiguation: merge_orchestrate vs merge_pr

Resume Semantics

Dry-Run

Anti-Patterns

Phase Transitions and Guards

Schema Discovery

Completion Criteria

Disambiguation:
`merge_orchestrate`
vs
`merge_pr`