Migrate Svelte Stores → Redux + Saga

Agent Preflight Compliance Contract

Before editing code or docs under this skill:

• MUST read this skill plus every linked skill/doc that applies to the touched files.
• MUST cite the applicable skills/docs in the implementation plan or completion handoff, including the rules used.
• MUST include verifier-ready evidence: searches, tests, or diff checks proving the cited rules were followed.
• MUST keep the migrated app on the Svelte Store family described by this subtree.
• SHOULD stop and ask when rules conflict or scope is unclear.
• NEVER claim completion when a required skill/doc was skipped or the handoff lacks compliance evidence.

Index for the migration playbook. Each step below links to a focused sub-skill; read them in order for a full slice migration.

Migration Policy

Classify ownership before converting syntax. Shared/domain state moves to Redux; ephemeral instance-local UI state and DOM-local focus, scroll, measurement, and widget lifecycle stay with the component. Async syntax alone does not change that boundary. Use ../../core/core-policy/SKILL.md → Setup — core rules and ./assessment/SKILL.md → Decision Framework for the classification evidence.

Migrate small technical increments, simplest and most isolated first. Branches, commits, and PR strategy come from the active task/repository instructions, not this reusable skill; see ./cleanup/SKILL.md → Workflow ownership. Keep the old owner until verification succeeds, then apply Remove Old Store Files and Pass-Through Wrapper Guard in ./cleanup/SKILL.md for deletion/shim evidence.

For every migrated slice, apply pure/no-op reducer rules in ../../core/reducers/SKILL.md → Do, serializable value rules in ../../core/state-serialization/SKILL.md → Do and Don't, and domain-effect conversion in ./side-effects/SKILL.md → Effect ownership boundary. Component reads/dispatch follow ../selector-lifecycle/SKILL.md → Call-mode map. Keep the app on the Svelte Store family throughout migration.

Recommended Order

Run these sub-skills in order. Steps 3–6 repeat per slice; step 7 closes out each slice.

1. ./assessment/SKILL.md → Output of the Assessment — Inventory stores/runes, record shared/domain vs local ownership, and choose the next leaf. Local-only findings need no Redux conversion.
2. ./setup/SKILL.md → Step 3 — Create the Store and Bootstrap It — Complete pre-migration setup once with an empty app-owned reducer map; add registrations as slices land.
3. ./writable-stores/SKILL.md → State: writable / $state → Initial State and State Updates: store.set / store.update → dispatch(action()) — Convert shared mutable state and updates with immutable actions/reducers.
4. ./derived-stores/SKILL.md → Examples — Convert shared derivations to named Store-bound selectors; compose upstream values rather than storing derived state.
5. ./side-effects/SKILL.md → Examples and Conversion Recipes — Convert domain effects to saga workers, watchers, or channels, preserving explicit cancellation ownership.
6. ./component-migration/SKILL.md → Examples and Rollout Order Per Component — Replace legacy imports, reads, and writes with selector readables and Store dispatch.
7. ./cleanup/SKILL.md → Rollback Strategy, Final Checklist Per Slice, and Cleanup Examples — Verify before deleting the old owner; record zero references, wrappers/shims, and tests. Roll back the complete technical unit if needed.

Primitive routing card

Only apply these routes after assessment classifies the state/effect as shared or domain-owned. The linked leaves, not this index, own the conversion procedures.

Source pattern	Canonical conversion owner
writable, $state, .set, .update	./writable-stores/SKILL.md → State Updates: store.set / store.update → dispatch(action())
readable(value, start)	State: ./writable-stores/SKILL.md → State: writable / $state → Initial State; domain start/stop logic: ./side-effects/SKILL.md → Effect ownership boundary
derived, $derived	./derived-stores/SKILL.md → Examples
$store reads and component writes	./component-migration/SKILL.md → Rollout Order Per Component
Domain $effect, fetch, persistence, timers, listeners/IPC	./side-effects/SKILL.md → Conversion Recipes
App saga startup formerly in onMount	../store/SKILL.md → App saga lifetime; mount-scoped startup cancels on unmount and restarts on remount, not automatically on Store creation
DOM-local lifecycle or instance-local visual state	./assessment/SKILL.md → Decision Framework; retain component ownership

Verification handoff

Record the assessment verdict and executed leaf routes in order. Attach the per-slice evidence specified in ./cleanup/SKILL.md → Final Checklist Per Slice and Cleanup Examples; do not substitute this index for those checks.