piv-slice-epic

/piv-slice-epic — Slice an Epic into PIV-Sized Tickets

The bridge between a strategic doc and the PIV loop. The epic doc is the destination; the PIV loop is the unit of motion; tickets are the bridge. /piv-slice-epic does the slicing.

Input

• $ARGUMENTS — the epic to slice and its architecture decisions. These arrive as one doc or two:
  • a single architected epic that carries its own ## Architecture section, or
  • an epic plus a separate, linked architecture page (the common case when the architecture lives beside the epic — e.g. a Confluence epic page and its linked architecture page, both passed as URLs). Read both.
  • greenfield: a PRD stands in for the epic. When the inputs are tracker references (Confluence/Jira URLs or keys), fetch them from the source via the Atlassian MCP. This is the load-bearing input: the architecture names the seams, data model, and missing pieces the slices must respect.
• Not prime-dependent. A primed session helps, but isn't required. If the codebase surface isn't loaded, this skill orients itself (Step 2) before slicing.

Process

Step 1 — Read the sources

Read the epic fully (goal, user stories, acceptance criteria, out-of-scope) and its architecture decisions, whether they are an ## Architecture section on the epic or a separate linked page (the approach, stack, data model, missing pieces, spikes). If the architecture is a separate page, fetch and read it too. The slicing has to respect those calls.

Step 2 — Orient on the code surface (if not already primed)

Slicing needs enough codebase awareness to judge what's independent vs dependent — file overlap, shared seams. If the session is already oriented, skip this. Otherwise explore it yourself — don't depend on a prior /prime-codebase: starting from the architecture's named seams, data model, and missing pieces, read the relevant files/dirs (e.g. the adapter interface, the orchestrator, the ingestion pipeline) to see what exists, what's reused, and where new code lands. Just enough to slice confidently — not a full re-derivation.

Step 3 — Decompose into PIV-sized slices

Break the epic into tickets. Scope these for AI, not for a human backlog — an agent loop carries far more than a traditional ticket: a small-to-medium implementation phase, ~8–10 subtasks, often 500–1500 lines of change (20–50% tests). A small epic might even be a single ticket. A well-sized ticket:

• Is one testable concern — easy to test, review, and prove on its own.
• Is one coherent unit — a vertical slice of behavior, not a horizontal layer.
• Has clear acceptance criteria of its own.
• Is small enough that one focused loop can one-shot it without context rot — not so large the agent loses the thread and returns diminish.

Split by dependency, by concern, or as a slim end-to-end slice (prove the whole flow thinly, then fatten it next loop) — whatever makes each ticket easiest to prove. If a slice is too big to test or review in one honest pass, split it further. The planning detail stays high regardless — it's the scope that's larger.

Step 4 — Slice for parallelizability

Map dependencies between tickets. Independent tickets — ones that don't touch the same files or rely on each other's output — can run in parallel worktrees (see /worktree-create). Mark which tickets are independent and which form a dependency chain. Slicing along vertical-slice-architecture seams maximizes independence.

Plan just-in-time: a dependent ticket waits until its dependency is implemented, not just sliced — building the dependency informs the dependent's plan, so planning it early plans against a guess. Independent tickets can be planned and run in parallel; dependent ones wait their turn.

Step 5 — Write the ticket breakdown

Write the tickets to your tracker (Jira via the Atlassian MCP, Linear, GitHub Issues, Archon's tasks) — or to a local docs/tickets/<epic-slug>.md if you're solo or have no tracker. Either way, every ticket carries its own context — that's what lets a loop pick it up later without re-reading the whole epic:

# Ticket Breakdown — <epic name>

## Epic summary — goal in 2-3 lines
## Tickets
   ### TICKET-1 — <title>
   - Scope / acceptance criteria — one testable concern
   - Per-ticket context: the doc sections, guides, and seams this ticket needs
     (e.g. "source-adapter guide · seam: adapter interface · AC #2 + #4 from the epic")
   - Files touched (estimate) · rough size (~500–1500 lines, incl. tests)
   - Depends on: <none / TICKET-x>
   ### TICKET-2 — ...
## Dependency graph
   <text or mermaid graph showing the order + parallel groups>
## Suggested execution order
   Wave 1 (parallel): TICKET-1, TICKET-3
   Wave 2: TICKET-2 (after TICKET-1 is implemented)

Output

A ticket breakdown in your tracker (or docs/tickets/<epic-slug>.md). Each ticket then enters its own PIV loop — straight to /piv-plan-implementation if it's well-scoped (it primes what it needs), or /prime-codebase first if it needs more codebase orientation. Priming is optional; the per-ticket context above is what makes that possible.

Notes

• Issue management is tool-agnostic: Jira (via Atlassian MCP), Linear, Notion, GitHub Issues, Archon's tasks — or just a folder of markdown files if you're solo. The tracker doesn't matter; the goal is to split the work just enough that each loop has the highest chance of one-shot success, so you can automate the loop.
• Greenfield: the same slicing applies to MVP phases instead of epic tickets.