feat: phases + tasks — per-task execution with phase directories

- A phase is now a directory: 00_phase.md (overview + task index) plus
  small, quick NN_task.md task files; complete/ mirrors todo/
- Task is the unit of execution: run-task.sh (one unit), run-phase.sh
  (phase to completion incl. 00_phase.md final pass), auto-phase.sh
  (all units in order); validate.sh gate runs after every task
- PHASE_COMMIT commits at phase boundaries (00_phase.md / legacy file moves)
- Legacy flat todo/NN_name.md files still execute as a single unit;
  new migrate-phases-to-tasks.sh converts them to the directory layout
- phase-status.sh reports per-task state and the next unit
- New task-template.md; phase templates now carry a Tasks index

convert-to-phased/SKILL.md

@@ -10,16 +10,17 @@ adopting an *existing* project into the phased-execution strategy. You audit
 the codebase, scaffold the `.agent/` planning structure, and write a phase
 roadmap that takes the project from its current state to the agreed target
 state. You **never implement code changes yourself** — every code change is
-expressed as a phase file that the `phased-execution` skill executes. And you
+expressed as a phase directory (a `00_phase.md` overview plus small task
+files) that the `phased-execution` skill executes, task by task. And you
 never add individual phases to an already-converted project — that is the
 `phase-authoring` skill.
 
 Phase state lives in files, not chat:
 
 - `.agent/PLAN.md` — master plan; **LOCKED DECISIONS** are binding
-- `.agent/phases/todo/NN_name.md` — pending phases (sort order = execution order)
-- `.agent/phases/complete/` — finished phases (read-only history)
-- `.agent/validate.sh` — the pass/fail gate for every phase (installed by the `phased-execution` skill on first run)
+- `.agent/phases/todo/NN_name/` — a pending phase: `00_phase.md` overview + `NN_task.md` task files (task sort order = execution order)
+- `.agent/phases/complete/` — finished phases, mirroring the todo/ layout (read-only history)
+- `.agent/validate.sh` — the pass/fail gate, run after every task (installed by the `phased-execution` skill on first run)
 
 ## Choosing the mode
 
@@ -86,7 +87,7 @@ Create (or merge into what already exists) with file tools:
   strategy, public-API principles, or UI/UX guidelines), and the phase roadmap.
 - **`AGENTS.md`** — the five base rules below, plus the domain additions.
 - **`.agent/phases/todo/`** — the roadmap from Phase 5.
-- **`.agent/phases/complete/`** — create the directory, leave it empty.
+- **`.agent/phases/complete/`** — create the directory, leave it empty (it mirrors `todo/` as phases complete).
 - **`.gitignore`** — add `.agent/` and `.agent/phase-sessions/` if missing.
 
 **AGENTS.md base rules:**
@@ -122,10 +123,12 @@ project's real checks (the foundation phase does that).
 
 ## Phase 5 — The Phase Roadmap
 
-Write sequential phase files into `.agent/phases/todo/` using
-`assets/phase-template.md` (mirrors the `phase-authoring` template; keep the
-sections identical). Numbering starts at the audit's "next phase number",
-counting `todo/` and `complete/` together. Never reuse or collide a number.
+Write sequential phase **directories** into `.agent/phases/todo/` — each
+`NN_name/` holds a `00_phase.md` overview (from `assets/phase-template.md`)
+and its task files (from `assets/task-template.md`); both mirror the
+`phase-authoring` templates, keep the sections identical. Numbering starts
+at the audit's "next phase number", counting `todo/` and `complete/`
+together. Never reuse or collide a number.
 
 Roadmap shape:
 
@@ -138,19 +141,23 @@ Roadmap shape:
 3. **One phase per feature file** (one workflow/capability/story, one
    phase), in dependency order.
 
-Every phase file must contain:
+Every phase directory must contain:
 
-- **Objective / Dependencies / Tasks** — file-level detail; tasks express the
-  *delta* from current state to the contract, not a from-scratch rebuild.
-- **Testing & Quality (mandatory)** — unit and integration tests for all
-  new/modified logic; coverage **>90%** on new/modified code; plus the domain
-  block below.
-- **Completion Criteria** — observable checks (commands to run, endpoints to
-  hit, artifacts to exist).
-- **Feature linkage** — the header line references the corresponding feature
-  file (`.agent/workflows/…`, `.agent/features/…`, or `.agent/user_stories/…`).
+- **`00_phase.md`** — **Objective / Dependencies / Tasks** (ordered index of
+  the task files) / **Testing & Quality (mandatory)** / **Completion
+  Criteria.** Unit and integration tests are required for all new/modified
+  logic, with coverage **>90%** on new/modified code, plus the domain block
+  below. Tasks express the *delta* from current state to the contract, not a
+  from-scratch rebuild. The header line references the corresponding feature
+  file (`.agent/workflows/…`, `.agent/features/…`, or
+  `.agent/user_stories/…`).
+- **Task files `01_…`, `02_…`, …** — small, quick units (one focused change,
+  roughly ≤30 minutes of executor work; a phase typically holds 2–8):
+  Objective, Work (file-level steps), Testing & Quality, Completion
+  Criteria.
 
-Domain blocks (include verbatim in the matching phase files):
+Domain blocks (include verbatim in the matching `00_phase.md`; the phase's
+final pass is where they are verified end-to-end):
 
 - **CLI:** `## CLI Contract Execution Phase` — instruct the executing agent
   to run ONLY the specific CliRunner contract test module for that workflow
@@ -175,8 +182,9 @@ Domain blocks (include verbatim in the matching phase files):
 - **Independent Viability:** each phase leaves the project functional and launchable.
 - **Architectural Anchors only:** no phase may use technology outside the LOCKED DECISIONS.
 - **No Regressions:** a phase must not alter the behavior of completed phases.
-- **Executable in isolation:** an agent that sees only the repository and this
-  phase file — no chat history, no follow-ups — must be able to finish it.
+- **Executable in isolation:** an agent that sees only the repository, the phase
+  overview, the completed task files, and one task file — no chat history, no
+  follow-ups — must be able to finish that task.
 
 ## Phase 6 — Version Control & Hand-Off
 
@@ -192,8 +200,8 @@ Domain blocks (include verbatim in the matching phase files):
 Finish by summarizing the Architectural Anchors, the feature decomposition,
 and the phase list (number, name, one-line objective). Then hand off:
 
-- **Execute:** the `phased-execution` skill — `run-phase.sh` for a single
-  phase, `auto-phase.sh` for the full pipeline.
+- **Execute:** the `phased-execution` skill — `run-task.sh` for a single
+  task, `run-phase.sh` for a phase, `auto-phase.sh` for the full pipeline.
 - **Extend:** the `phase-authoring` skill for individual additional phases.
 
 ## Strict Operational Rules