Epic Ship

Epic Ship

Runs a multi-phase epic (a markdown plan doc with a phase list, e.g. docs/epics/epic-.md) phase by phase, calling the ship-pr skill once per phase for the actual worktree/implement/verify/PR/merge/cleanup mechanics, until every phase is shipped or you hit an explicit review checkpoint. This is the sequential composition operator of the ship stack: parallel-ship fans out when changes are independent; this skill loops when phase N+1 builds on phase N's code.

The default failure mode this skill exists to fix is stalling after a routine merge waiting to be told to continue. ship-pr ships one PR and stops - epic-ship is what decides to call it again immediately.

Step 0: Reconcile against reality first

Before touching anything:

1. git status and git branch --show-current at the repo root - confirm it's on the default branch and clean. If not clean and the changes aren't yours, stop and tell the user.
2. git worktree list - confirm no stray worktree already covers this epic's phases.
3. Read the epic doc fully: phase list, current status column, and any explicit checkpoint markers (see Step 3).
4. gh pr list --search "" --state all and git log --oneline -20 - confirm what's actually already merged before trusting the epic doc's status table. Epic docs drift; git and GitHub are the source of truth. This step exists because past sessions have reported phases as unshipped when they'd already landed, or vice versa - always reconcile before planning work.

Step 1: Plan the run

List the unshipped phases in order. For each, note what it touches (which packages/apps - and which specialized subagent fits, if the project defines any) and whether it's DB/migration work (regenerate types afterward if the project has a typegen step).

Then re-order for risk, not just dependency

Epic docs number phases in dependency order (DB -> backend -> frontend). That is not always a safe merge order. Before shipping anything, ask of each phase:

> Does this phase widen what the server permits or creates, while the code that handles the new case safely is still unmerged?

If yes, ship the guard phase first (it is inert until the permission exists), or merge both back to back. Never merge and deploy the permission first.

Example: an epic adds restricted sub-accounts. Phase 2 lets the backend create them; phase 3 teaches the frontend to recognize them and hide the surfaces they shouldn't see. Merge and deploy phase 2 first, and every production build until phase 3 lands shows those accounts everything the epic existed to hide. The logic of both phases is right; only the merge order is wrong - and the epic doc's dependency numbering told you to do it.

Concretely, when a phase is permission-widening and its guard is a later phase:

• Reorder so the guard merges first, or
• Hold the permission phase on its branch until the guard is merged, or
• If dependency genuinely forces the original order, merge the permission but do not deploy it until the guard lands.

Say which of these you picked in the Step 4 status board, so the choice is visible.

Step 2: Per-phase loop

For each phase, in order, until you hit a checkpoint (Step 3) or run out of phases, invoke the ship-pr skill for that phase's change, with two epic-specific overrides on top of its normal behavior:

• Branch/worktree name: /epic--phase-- (ship-pr's own branch-type table still decides the prefix) instead of a plain slug, so phases from the same epic are identifiable in git worktree list and gh pr list.
• PR body: reference the epic doc and phase number, not just the change on its own.

ship-pr owns the mechanics: worktree, implement (delegate to a matching specialized subagent if the project defines them, rather than doing everything inline), verify (including any phase-specific verification query named in the epic doc - run it live, against real data, don't just document it), ship, and the CI-check-before-merge decision.

Once ship-pr merges and cleans up the worktree:

1. Update the epic doc's phase status table, in the same PR or a fast-follow docs commit.
2. If this phase is not a checkpoint (Step 3): invoke ship-pr for the next phase immediately, without waiting for a prompt.
3. If it is a checkpoint: stop here, don't start the next phase.

Step 3: What counts as a checkpoint

Treat a phase as a hard stop - report status and wait for the user - when the epic doc marks it explicitly (e.g. "STOP", "review", "awaiting go-ahead", "manual deploy") OR when it involves any of:

• A manual production step with no CLI path (e.g. a dashboard-only config change, a production deploy the user runs by hand)
• A schema change with no rollback path already tested
• Anything touching billing/payment webhooks, auth/SSO, or row-level-security policies on tables with existing user data
• The epic doc doesn't say and you're genuinely unsure whether it's reversible
• The phase PR's CI came back red for a reason ship-pr's own verification didn't already predict (a genuine unknown, not a known quirk ship-pr already stops on)

Everything else: merge and keep going.

Step 4: Status board

After finishing all remaining phases, or on hitting a checkpoint, report a table: Phase | PR # | Status (merged / awaiting review / blocked) | Note. Keep it to one screen - this is a status report, not a retrospective.

Hard rules

• Never push directly to the default branch. Every phase is its own PR.
• Every phase's worktree forks fresh from the remote default branch via ship-pr's worktree-new.sh - never stack one phase's branch on another unmerged phase's branch, even though they're part of the same epic. When phase N+1's worktree is created, phase N must already be merged, or phase N+1 will conflict when phase N lands.
• Close each worktree immediately after its PR merges (worktree-close.sh) - don't batch cleanup to the end of the epic.
• One epic = many PRs (one per phase), not one giant PR. Epic-scale work is the exception to any general "bundle into one PR" preference.

See also

• ship-pr - the atomic single-PR mechanics this skill calls once per phase; invoke it directly for anything that isn't a multi-phase epic
• parallel-ship - the parallel counterpart: fan out independent PRs from one analysis pass

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: davidtheproduct
• Source: davidtheproduct/claude-ship-skills
• License: MIT

Install and usage instructions live in the source repository linked above.