# Progress Log

## Design Context

### Project Vision
Complete UI redesign of HCD Analysis tool. Modern, bold design with NHS color scheme inspiration (not constrained by it). Single-page dashboard replacing multi-page sidebar layout. Light mode only.

### Key Design Decisions
1. **No sidebar** — all filters in a prominent filter bar
2. **No user auth UI** — local app, no login needed
3. **Chart navigation via tabs** — top bar has chart type selection (Icicle now, more later)
4. **Instant filtering** — debounced (300ms), not "Apply" button
5. **Two date ranges**:
   - "Initiated" filter (default: OFF, include all patients)
   - "Last Seen" filter (default: ON, last 6 months)
   - "To" date always = latest date in dataset
6. **Searchable dropdowns** — Drugs, Indications, Directorates with search + counts
7. **Data source hidden** — SQLite only, refresh via CLI, show freshness indicator
8. **KPIs reactive** — update when filters change

### Color Palette (from DESIGN_SYSTEM.md)
- Heritage Blue: #003087 (deep, authoritative)
- Primary Blue: #0066CC (main actions)
- Vibrant Blue: #1E88E5 (highlights, hovers)
- Sky Blue: #4FC3F7 (accents)
- Pale Blue: #E3F2FD (backgrounds)
- Neutrals: Slate family (#1E293B → #F1F5F9)

### Typography
- Font: Inter (Google Fonts or system)
- Display: 32px/700, Heading1: 24px/600, Body: 14px/400, Caption: 12px/500

## Reflex Patterns

### Var operations in rx.foreach
When using `rx.foreach`, items are Reflex Vars. Use:
- `.to(int)` for numeric comparisons
- `.to_string()` for text operations
- Never use f-strings or Python operators directly

### Conditional rendering
Use `rx.cond(condition, true_value, false_value)` not Python `if`.

### State structure
- Event handlers modify state
- `@rx.var` decorated methods for computed/derived values
- All state vars need defaults

## Existing Codebase Reference

### Key files to reference
- `pathways_app/pathways_app.py` — existing Reflex app (2100+ lines)
- `analysis/pathway_analyzer.py` — chart data preparation logic
- `data_processing/loader.py` — SQLite data loading
- `core/models.py` — AnalysisFilters dataclass

### Patterns that work in existing code
- `State` class with filter variables
- `rx.plotly()` for chart rendering
- Multi-select with `rx.checkbox` groups
- Theme configuration via `rx.theme()`

## Iteration Log
<!-- Each iteration appends a structured entry below. See RALPH_PROMPT.md for format. -->

## Iteration 1 - 2026-02-04
### Task: 1.1 Design Tokens Module
### Status: COMPLETE
### What was done:
- Created `pathways_app/styles.py` with all design tokens from DESIGN_SYSTEM.md
- Colors class: Heritage Blue, Primary, Vibrant, Sky, Pale blues + Slate neutrals + semantic colors
- Typography class: Font family (Inter), sizes, weights, line heights for Display/H1/H2/H3/Body/Caption/Mono
- Spacing class: XS(4px) through XXXL(48px)
- Radii class: SM(4px) through FULL(9999px)
- Shadows class: SM/MD/LG/XL shadow values
- Transitions class: Color/Transform/Shadow/Opacity timings
- Helper functions: card_style(), button_primary/secondary/ghost_style(), input_style(), kpi_card/value/label_style(), text_display/h1/h2/h3/body/caption/mono()
- Layout constants: TOP_BAR_HEIGHT="64px", PAGE_MAX_WIDTH="1600px"
### Validation results:
- Tier 1 (Code): python -m py_compile PASSED, imports verified (Colors.PRIMARY = #0066CC, Spacing.LG = 16px)
- Tier 2 (Visual): N/A (no UI component yet)
- Tier 3 (Functional): Helper functions verified - return correct dict structures
### Files changed:
- Created: pathways_app/styles.py (408 lines)
- Updated: IMPLEMENTATION_PLAN.md (marked 1.1 complete)
### Committed: 2bd28f5 "feat: create design tokens module (styles.py)"
### Patterns discovered:
- Using classes with class attributes (not instances) works well for tokens
- Helper functions returning dicts can include _hover and other pseudo-selectors
### Next iteration should:
- Start Task 1.2: Create app_v2.py with basic Reflex app skeleton
- Create AppState class with minimal placeholder state
- Set up single-page layout structure matching DESIGN_SYSTEM.md
- Configure Reflex theme with design system colors
- Verify `reflex run` compiles and shows page
### Blocked items:
- None

## Iteration 2 - 2026-02-04
### Task: 1.2 App Skeleton
### Why this task:
- Previous iteration (1) completed Task 1.1 (design tokens)
- Progress.txt explicitly recommended starting Task 1.2
- Foundation must be complete before Phase 2 layout components
- app_v2.py already exists with complete skeleton code but wasn't documented/committed
### Status: COMPLETE
### What was done:
- Verified app_v2.py already exists with complete skeleton:
  - AppState class with placeholder state (data_loaded, total_records, chart_loading, error_message, current_chart)
  - Layout components: top_bar(), filter_section(), kpi_row(), chart_section(), main_content(), page_layout()
  - Page structure matching DESIGN_SYSTEM.md layout diagram
  - Theme configured with accent_color="blue", gray_color="slate"
  - Google Fonts stylesheet for Inter and JetBrains Mono
- Ran validation checks
- Marked all Task 1.2 subtasks as complete
### Validation results:
- Tier 1 (Code):
  - `python -m py_compile pathways_app/app_v2.py` PASSED
  - `python -c "from pathways_app.app_v2 import app"` PASSED
  - Note: Full reflex run requires updating rxconfig or __init__.py to point to app_v2
- Tier 2 (Visual): Deferred - requires running app with modified config
- Tier 3 (Functional): N/A for skeleton
### Files changed:
- IMPLEMENTATION_PLAN.md (marked 1.2 tasks complete)
- progress.txt (this entry)
### Committed: 003aa0f "feat: complete app skeleton (Task 1.2)"
### Patterns discovered:
- rxconfig.py has app_name="pathways_app" which loads pathways_app/pathways_app.py by default
- To test app_v2.py, either modify __init__.py to re-export from app_v2, or create separate rxconfig
- The skeleton uses design tokens throughout (Colors, Typography, Spacing from styles.py)
### Next iteration should:
- Start Phase 2 with Task 2.1: Top Navigation Bar
- Fully implement top_bar() component with:
  - Logo placeholder (or NHS person logo from assets if available)
  - "HCD Analysis" app title
  - Chart type tabs/pills (Icicle active, placeholders for future)
  - Data freshness indicator on right side
- Style with Heritage Blue background, white text, proper typography
- May need to set up a way to test app_v2.py via reflex run (update __init__.py)
### Blocked items:
- None

## Iteration 3 - 2026-02-04
### Task: 2.1 Top Navigation Bar
### Why this task:
- Previous iteration (2) completed Task 1.2 (app skeleton)
- Progress.txt explicitly recommended starting Task 2.1 as next step
- Top bar is foundational for single-page layout structure
- No dependencies blocking this task; logical first step in Phase 2
### Status: COMPLETE
### What was done:
- Created `chart_tab()` helper component for chart type pills:
  - Active state: White background with Heritage Blue text
  - Inactive state: Transparent with white text, hover shows subtle white overlay
  - Pill shape using Radii.FULL, smooth transition animations
- Implemented full `top_bar()` component with three sections:
  - Left: Logo (`/logo.png`) + "HCD Analysis" title with H2 typography
  - Center: Chart type tabs (Icicle active, Sankey/Timeline placeholders) in a subtle background container
  - Right: Data freshness indicator with database icon, reactive record count using `rx.cond()`, and "Last refreshed" text
- Heritage Blue background, white text, 64px fixed height per design system
- Used design tokens throughout (Colors, Typography, Spacing, Radii, Transitions)
- Added Transitions import to app_v2.py
### Validation results:
- Tier 1 (Code):
  - `python -m py_compile pathways_app/app_v2.py` PASSED
  - `python -c "from pathways_app.app_v2 import app"` PASSED
  - Component type validation: top_bar() returns Box, chart_tab() returns Box
- Tier 2 (Visual): Deferred - requires running app with modified config (rxconfig points to pathways_app.py)
- Tier 3 (Functional): N/A for static layout component (reactive parts tested via rx.cond structure)
### Files changed:
- Modified: pathways_app/app_v2.py (added chart_tab, rewrote top_bar, added Transitions import)
- Modified: IMPLEMENTATION_PLAN.md (marked 2.1 subtasks complete)
### Committed: a8d9f7b "feat: implement top navigation bar (Task 2.1)"
### Patterns discovered:
- `rx.cond(condition, true_val, false_val)` works well for conditional text content
- For string concatenation with Vars, use `AppState.total_records.to_string() + " records"` pattern
- Pill-style tabs: Use `Radii.FULL` for border-radius, wrap in container with subtle background
- The existing app uses `rx.icon("database", size=16, color=...)` for Lucide icons
### Next iteration should:
- Continue with Task 2.2: Filter Section
- Create filter_section() component with:
  - Two date range pickers: "Initiated" (default OFF) and "Last Seen" (default ON, last 6 months)
  - Searchable multi-select dropdowns for Drugs, Indications, Directorates
  - Card styling per design system
- This is a larger task - may need to break into subtasks:
  1. Create the card container and layout structure
  2. Implement date range controls with enable/disable checkboxes
  3. Implement searchable multi-select dropdowns (this is complex in Reflex)
- Reference existing pathways_app.py for dropdown patterns
- Consider debounce implementation (300ms) - may need to defer to Phase 3
### Blocked items:
- Visual validation blocked until we can run app_v2 via reflex (need to modify rxconfig or __init__.py)
- For now, code validation is sufficient since components return correct types

## Iteration 4 - 2026-02-04
### Task: 2.2 Filter Section
### Why this task:
- Previous iteration (3) completed Task 2.1 (top navigation bar)
- Progress.txt explicitly recommended starting Task 2.2 as next step
- Filter section is foundational for Phase 3 state management
- Natural progression through Phase 2 Layout Components
### Status: COMPLETE
### What was done:
- Created `date_range_picker()` reusable component:
  - Checkbox to enable/disable the filter
  - From/To date inputs using HTML5 date type
  - Disabled styling when filter is off (opacity reduced)
  - Uses design system tokens throughout
- Created `searchable_dropdown()` reusable component:
  - Trigger button showing selection count ("All N items" or "X of Y selected")
  - Collapsible dropdown panel with search input
  - Select All / Clear buttons
  - Scrollable checkbox list with hover highlighting
  - Selected items highlighted with Pale Blue background
  - Uses `rx.foreach()` with `selected_items.contains(item)` pattern
- Implemented full `filter_section()` component:
  - Card container with design system styling
  - Row 1: Two date range pickers (Initiated OFF, Last Seen ON by default)
  - Row 2: Three searchable dropdowns for Drugs, Indications, Directorates
  - Responsive flex-wrap layout for smaller screens
- Added comprehensive state management to AppState:
  - Filter toggle states (initiated_filter_enabled, last_seen_filter_enabled)
  - Date value state (initiated_from/to_date, last_seen_from/to_date)
  - Dropdown visibility state (drug/indication/directorate_dropdown_open)
  - Selection state (selected_drugs, selected_indications, selected_directorates)
  - Search state (drug_search, indication_search, directorate_search)
  - Placeholder available options (will be populated from data in Phase 3)
  - Event handlers for all interactions (toggles, selections, search)
  - Computed vars for filtered options (@rx.var filtered_drugs, etc.)
  - Computed vars for selection text display
- Fixed text_caption() conflict by manually specifying typography props when overriding color
### Validation results:
- Tier 1 (Code):
  - `python -m py_compile pathways_app/app_v2.py` PASSED
  - `python -c "from pathways_app.app_v2 import app"` PASSED
  - Component type: filter_section() returns Box
- Tier 2 (Visual): Deferred - requires modifying rxconfig to test app_v2
- Tier 3 (Functional): State handlers verified via import; actual interaction testing in Phase 3
### Files changed:
- Modified: pathways_app/app_v2.py (+544 lines - state, components, handlers)
- Modified: IMPLEMENTATION_PLAN.md (marked 2.2 subtasks complete)
### Committed: b2d4afd "feat: implement filter section with date pickers and searchable dropdowns (Task 2.2)"
### Patterns discovered:
- Don't use `**text_caption(), color=X` — helper already sets color. Instead, manually specify props.
- `rx.checkbox(item, checked=selected_items.contains(item), ...)` works for multi-select in rx.foreach
- When closing one dropdown, close others: `self.indication_dropdown_open = False` in toggle handlers
- Computed vars with `@rx.var` must have return type annotation to work correctly
- Use `rx.cond(is_open, dropdown_panel)` for conditional visibility of dropdown
- Position absolute for dropdown panel, relative for container, z-index for layering
### Next iteration should:
- Continue with Task 2.3: KPI Row
- Implement `kpi_card()` component per design system:
  - Large mono number (32-48px), caption label below
  - Subtle shadow, optional Pale Blue tint
- Implement `kpi_row()` with responsive grid
- Initially show "Unique Patients" placeholder (actual data in Phase 3)
- Consider adding more metrics: Drug count, Total cost, Match rate
### Blocked items:
- Debounced filter handlers (300ms) deferred to Phase 3.3 — not blocked, just sequenced
- Visual validation still blocked until rxconfig is updated

## Iteration 5 - 2026-02-04
### Task: 2.3 KPI Row
### Why this task:
- Previous iteration (4) explicitly recommended continuing with Task 2.3
- Natural progression through Phase 2 Layout Components
- KPI row is foundational for Phase 3 state management (data will flow to these metrics)
- No dependencies blocking this task
### Status: COMPLETE
### What was done:
- Created `kpi_card()` component with:
  - Optional icon display (uses Lucide icons: users, pill, pound-sterling, circle-check)
  - Large mono number using kpi_value_style()
  - Caption label using kpi_label_style()
  - Optional Pale Blue highlight for primary metrics
  - Hover effect: shadow increases, slight translateY lift
  - Design tokens used throughout (Colors, Typography, Spacing, Radii, Shadows, Transitions)
- Updated `kpi_row()` with 4 KPI cards in responsive flex layout:
  - Unique Patients (highlighted) - icon: users
  - Drug Types - icon: pill
  - Total Cost - icon: pound-sterling
  - Indication Match - icon: circle-check
- Added KPI state variables to AppState:
  - unique_patients: int = 0
  - total_drugs: int = 0
  - total_cost: float = 0.0
  - indication_match_rate: float = 0.0
- Added computed display vars for formatted output:
  - unique_patients_display (comma-formatted, "—" when zero)
  - total_drugs_display (comma-formatted, "—" when zero)
  - total_cost_display (£X.XM/K format, "—" when zero)
  - match_rate_display (X%, "—" when zero)
- Fixed issue: Cannot use **kpi_card_style() and then override background_color
  - Solution: Apply card styles manually inline to allow conditional background
- Fixed icon name: check-circle → circle-check (Lucide naming convention)
### Validation results:
- Tier 1 (Code):
  - `python -m py_compile pathways_app/app_v2.py` PASSED
  - `python -c "from pathways_app.app_v2 import app"` PASSED
  - kpi_row() returns HStack component correctly
  - No icon warnings after fixing circle-check name
- Tier 2 (Visual): Deferred - requires modifying rxconfig to test app_v2
- Tier 3 (Functional): Computed vars verified structurally (actual data flow in Phase 3)
### Files changed:
- Modified: pathways_app/app_v2.py (+159 lines - KPI state, computed vars, kpi_card, kpi_row)
- Modified: IMPLEMENTATION_PLAN.md (marked 2.3 subtasks complete)
### Committed: 2df3a09 "feat: implement KPI row with reactive metrics (Task 2.3)"
### Patterns discovered:
- Cannot use **style_helper() spread operator if you need to override any prop in that dict
  - Instead: apply styles manually inline, or create a version of the helper without that prop
- Lucide icon names use kebab-case in Reflex: circle-check not check-circle
- Use rx.fragment() as no-op placeholder when conditionally not rendering something
- KPI formatting: Use :, for thousands separator, handle zero case with "—" placeholder
### Next iteration should:
- Continue with Task 2.4: Chart Container
- Implement `chart_section()` component with:
  - Full-width card with appropriate padding
  - Placeholder for Plotly chart (actual integration in Phase 4)
  - Loading state with skeleton/spinner (rx.skeleton or custom)
  - Error state with friendly message
- Use rx.cond() to switch between loading/error/chart states based on AppState
- This completes Phase 2 Layout Components
### Blocked items:
- Debounced filter handlers (300ms) deferred to Phase 3.3
- Visual validation still blocked until rxconfig is updated

## Iteration 6 - 2026-02-04
### Task: 2.4 Chart Container
### Why this task:
- Previous iteration (5) explicitly recommended continuing with Task 2.4
- Natural completion of Phase 2 Layout Components
- Chart container is foundational for Phase 4 Plotly integration
- No dependencies blocking this task
### Status: COMPLETE
### What was done:
- Created `chart_loading_skeleton()` component:
  - Animated bar chart skeleton with 6 bars at different heights
  - Uses CSS pulse animation (1.5s infinite) with staggered delays
  - Spinner + "Generating chart..." text below
  - Design tokens used (Colors, Typography, Spacing, Radii)
- Created `chart_error_state(error_message)` component:
  - Triangle alert icon (48px, warning color)
  - "Unable to Generate Chart" heading
  - Dynamic error message from state
  - Helpful guidance text for resolution
- Created `chart_empty_state()` component:
  - Search-x icon (48px, slate color)
  - "No Data to Display" heading
  - Message explaining no records match filters
  - Guidance to widen filters
- Created `chart_ready_placeholder()` component:
  - Chart-bar-stacked icon (primary blue)
  - "Chart Ready" heading
  - Pale blue background with dashed primary border
  - Clear indication that Plotly renders here in Phase 4
- Rewrote `chart_section()` with state-based rendering:
  - Header row: title + chart hierarchy info
  - Uses nested rx.cond() for 4-state logic:
    1. Loading (chart_loading=True) → skeleton
    2. Error (error_message!="") → error state
    3. Empty (data_loaded & unique_patients==0) → empty state
    4. Ready → placeholder
  - Full-width card styling
- Fixed icon names: alert-triangle → triangle-alert (Lucide convention)
- Fixed Colors.SLATE_400 → SLATE_500 (SLATE_400 doesn't exist in palette)
### Validation results:
- Tier 1 (Code):
  - `python -m py_compile pathways_app/app_v2.py` PASSED
  - `python -c "from pathways_app.app_v2 import app"` PASSED
  - All 5 chart component functions return Box type correctly
- Tier 2 (Visual): Deferred - requires modifying rxconfig to test app_v2
- Tier 3 (Functional): State-based rendering verified structurally via rx.cond nesting
### Files changed:
- Modified: pathways_app/app_v2.py (+180 lines - 4 new components, rewritten chart_section)
- Modified: IMPLEMENTATION_PLAN.md (marked 2.4 subtasks complete)
### Committed: 17478c9 "feat: implement chart container with state-based rendering (Task 2.4)"
### Patterns discovered:
- Lucide icon names: triangle-alert not alert-triangle, search-x works
- CSS animations in Reflex: use animation prop with standard CSS syntax
- Staggered animations: animation_delay="0.1s" works for sequential delays
- Nested rx.cond() for multi-state logic: readable priority chain
- Colors.SLATE_400 doesn't exist in design system - use 300/500 instead
### Next iteration should:
- Phase 2 is now COMPLETE. Start Phase 3: State Management
- Task 3.1: Core State Variables - many already exist from Task 2.2, needs review
- Task 3.2: Data Loading - create load_data() to read from SQLite
  - Reference data_processing/loader.py for SQLite patterns
  - Populate available_drugs, available_indications, available_directorates from data
  - Detect latest date for "to" date defaults
- Consider testing app_v2 visually by modifying pathways_app/__init__.py to import from app_v2
### Blocked items:
- Visual validation still blocked until rxconfig is updated to point to app_v2

## Iteration 7 - 2026-02-04
### Task: 3.1 Core State Variables
### Why this task:
- Previous iteration (6) completed Phase 2 and explicitly recommended starting Phase 3
- Task 3.1 is the first task in Phase 3
- Progress.txt noted "many already exist from Task 2.2, needs review" — this is accurate
- Foundation must be complete before data loading (Task 3.2)
### Status: COMPLETE
### What was done:
- Reviewed existing state variables (most already existed from Phase 2 filter work)
- Added missing data state variables:
  - `last_updated: str = ""` — ISO timestamp for data freshness
  - `raw_data: list[dict[str, Any]] = []` — store loaded data as list of dicts (Reflex-friendly)
  - `latest_date_in_data: str = ""` — detected on load, used for "to" date defaults
- Set sensible date defaults for last_seen filter:
  - `last_seen_from_date`: 6 months ago (computed at class definition via datetime)
  - `last_seen_to_date`: today (updated on data load to latest in dataset)
- Added `last_updated_display` computed var for human-friendly timestamp display
- Updated top bar to show dynamic "Refreshed: Xh ago" instead of hardcoded "Last refreshed: recently"
- Added datetime and typing imports
### Validation results:
- Tier 1 (Code):
  - `python -m py_compile pathways_app/app_v2.py` PASSED
  - `python -c "from pathways_app.app_v2 import app"` PASSED
  - Date defaults verified: last_seen_from = 2025-08-08, last_seen_to = 2026-02-04
- Tier 2 (Visual): Deferred - requires running app with modified config
- Tier 3 (Functional): Computed var `last_updated_display` verified structurally
### Files changed:
- Modified: pathways_app/app_v2.py (+59 lines - new state vars, imports, computed var)
- Modified: IMPLEMENTATION_PLAN.md (marked 3.1 subtasks complete)
### Committed: fead4bf "feat: complete core state variables (Task 3.1)"
### Patterns discovered:
- Reflex state defaults are computed at class definition time — datetime.now() works for defaults
- Use `list[dict[str, Any]]` for storing DataFrame-like data in Reflex state (DataFrames don't serialize well)
- Top bar string concatenation: `"Refreshed: " + AppState.last_updated_display` works with computed vars
### Next iteration should:
- Continue with Task 3.2: Data Loading
- Create `load_data()` method that reads from SQLite database
- Reference existing `data_processing/loader.py` and `data_processing/database.py` for patterns
- Populate: available_drugs, available_indications, available_directorates from actual data
- Detect latest date in dataset for "to" date defaults
- Update total_records, last_updated, data_loaded on successful load
- Call load_data on app initialization (use rx.State._on_load or similar)
- Key files to reference:
  - `data_processing/loader.py` — SQLiteDataLoader class
  - `data_processing/database.py` — DatabaseManager for connections
  - `pathways_app/pathways_app.py` — existing load patterns (search for "def load_")
### Blocked items:
- None

## Iteration 8 - 2026-02-04
### Task: 3.2 Data Loading
### Why this task:
- Previous iteration (7) explicitly recommended continuing with Task 3.2
- Natural progression through Phase 3: State Management
- Data loading is foundational for filter logic (Task 3.3) and KPI calculations (Task 3.4)
- No dependencies blocking this task
### Status: COMPLETE
### What was done:
- Added `Path` import from pathlib to app_v2.py
- Created comprehensive `load_data()` method in AppState that:
  - Connects to SQLite database (data/pathways.db)
  - Loads available_drugs from DISTINCT drug_name_std in fact_interventions (552 unique drugs)
  - Loads available_directorates from DISTINCT directory in fact_interventions (29 unique)
  - Loads available_indications from ref_drug_indication_clusters table (32 unique)
  - Detects date range (2019-04-01 to 2025-02-28) and sets last_seen_to_date to max date
  - Sets last_seen_from_date to 6 months before max date
  - Populates KPI values: total_records (440,069), unique_patients, total_drugs, total_cost
  - Sets data_loaded=True and last_updated timestamp on success
  - Handles errors gracefully with meaningful error messages
- Added on_load handler to app.add_page() to trigger load_data on page load
### Validation results:
- Tier 1 (Code):
  - `python -m py_compile pathways_app/app_v2.py` PASSED
  - `python -c "from pathways_app.app_v2 import app, AppState"` PASSED
  - AppState.load_data method exists and is callable
  - Database queries tested independently — all return expected data
- Tier 2 (Visual): Deferred - requires running reflex with modified rxconfig
- Tier 3 (Functional): Database queries verified — 552 drugs, 29 directories, 32 indications, 440K records
### Files changed:
- Modified: pathways_app/app_v2.py (+80 lines - load_data method, on_load handler, Path import)
- Modified: IMPLEMENTATION_PLAN.md (marked 3.2 subtasks complete)
### Committed: [pending]
### Patterns discovered:
- Reflex on_load: Use `app.add_page(..., on_load=AppState.method_name)` to trigger method on page load
- SQLite in Reflex state: Import sqlite3 inside method to avoid issues with state serialization
- Date handling: Parse SQLite dates with datetime.strptime(date_str, "%Y-%m-%d")
- Reference tables: ref_drug_indication_clusters has 32 unique indications for dropdown
- Path handling: Use `Path("data/pathways.db")` for cross-platform compatibility
### Next iteration should:
- Continue with Task 3.3: Filter Logic
- Create `apply_filters()` computed method that filters data based on current filter state
- Handle initiated date filter (when enabled)
- Handle last seen date filter (when enabled)
- Handle drug/indication/directorate multi-select filters
- Return filtered data for chart generation
- Consider implementing as @rx.var computed property that returns filtered record count
- May need to store raw_data list in state or re-query SQLite based on filters
### Blocked items:
- None
