docs: add prompt for next Devin session to continue cleanup work

Co-Authored-By: Justin Edmund <justin@jedmund.com>

NEXT_SESSION_PROMPT.md

@@ -0,0 +1,89 @@
+# Prompt for Next Devin Session
+
+## Task
+Continue cleaning up type errors in the `svelte-main` branch of `jedmund/hensei-web`. The goal is to get the build green by fixing all remaining type errors.
+
+## Context
+This is a Svelte 5 rewrite of a Granblue Fantasy team composition app. The previous session reduced type errors from ~412 to ~378. A detailed plan of completed and remaining work is in `CLEANUP_PLAN.md`.
+
+## Starting Point
+1. Checkout the `svelte-main` branch in `/home/ubuntu/repos/hensei-web`
+2. Run `pnpm check 2>&1 | grep -c "Error:"` to see current error count (~378)
+3. Review `CLEANUP_PLAN.md` for detailed context on what's been fixed and what remains
+
+## Remaining Type Errors to Fix (Priority Order)
+
+### 1. 'firstItem' and 'item' Possibly Undefined (27 errors)
+- **File**: `src/routes/teams/new/+page.svelte`
+- **Fix**: Add null checks before accessing `items[0]` and in forEach loops
+- **Example**: Change `const firstItem = items[0]` to include a guard like `if (!items[0]) return`
+
+### 2. PartyCtx Missing openPicker Property (8 errors)
+- **Fix**: Find the `PartyCtx` type definition and add `openPicker` method signature
+- **Search**: `grep -rn "PartyCtx" src/lib/types/`
+
+### 3. Missing Paraglide Translation Keys (18 errors)
+- **Keys needed**: `context_view_details`, `context_replace`, `context_remove`
+- **Files to update**: `project.inlang/messages/en.json` and `project.inlang/messages/ja.json`
+- **Then run**: `pnpm paraglide-js compile --project ./project.inlang`
+
+### 4. Summon/Weapon Missing hp/atk Properties (18 errors)
+- **File**: `src/lib/api/adapters/entity.adapter.ts`
+- **Fix**: Update `Summon` interface to include nested `hp` and `atk` objects (similar to Character fix already done)
+
+### 5. exactOptionalPropertyTypes Violations (~15 errors)
+- **Issue**: Props with `undefined` values passed to components that don't accept undefined
+- **Fix**: Update component Props interfaces to accept `| undefined` for optional properties
+
+### 6. Select.svelte ItemIndicator Errors (4 errors)
+- **File**: `src/lib/components/ui/Select.svelte`
+- **Issue**: `Select.ItemIndicator` doesn't exist in bits-ui v2.9.6
+- **Fix**: Check bits-ui docs for correct component or remove usage
+
+### 7. DropdownItem.svelte asChild Issue (2 errors)
+- **File**: `src/lib/components/ui/dropdown/DropdownItem.svelte`
+- **Issue**: `asChild` prop doesn't exist in bits-ui
+- **Fix**: Use `child` snippet pattern instead
+
+### 8. Button.svelte Icon Type Issues (2 errors)
+- **File**: `src/lib/components/ui/Button.svelte`
+- **Fix**: Add conditional rendering `{#if icon}` before Icon component
+
+### 9. Button Variant "outlined" (3 errors)
+- **Fix**: Change "outlined" to valid variant (check Button component for valid options)
+
+### 10. maxLength vs maxlength (4 errors)
+- **Fix**: Change `maxLength` to `maxlength` (lowercase) in input elements
+
+## Commands Reference
+```bash
+# Check error count
+pnpm check 2>&1 | grep -c "Error:"
+
+# Analyze error patterns
+pnpm check 2>&1 | grep "Error:" | sort | uniq -c | sort -rn | head -20
+
+# Find specific errors
+pnpm check 2>&1 | grep -B2 "specific error text"
+
+# Run lint
+pnpm lint
+
+# Run build
+pnpm build
+
+# Regenerate Paraglide translations
+pnpm paraglide-js compile --project ./project.inlang
+```
+
+## Important Notes
+- This project uses `exactOptionalPropertyTypes: true` in tsconfig, which is stricter than normal TypeScript
+- The codebase uses Svelte 5 runes (`$state`, `$derived`, `$effect`)
+- bits-ui v2.9.6 is used for UI components - check their docs for correct API
+- Focus on errors only, not warnings (per user instruction)
+- Push directly to `svelte-main` branch when done
+
+## Success Criteria
+- `pnpm check` returns 0 errors
+- `pnpm lint` passes
+- `pnpm build` succeeds