Paul Trowbridge
64f3cc58e8
Document the @perspective-dev distribution (not FINOS @finos/perspective): loader (npm /inline vs CDN), the version trilemma (inline needs 4.5.x, viewer-d3fc caps at 4.4.1, charts need 4.4.1 — can't have all three), Arrow vs JSON delivery constraints, deploy pattern, and an upgrade smoke test. Correct CLAUDE.md's stale perspective.finos.org link to the actual @perspective-dev repo. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
121 lines
7.4 KiB
Markdown
121 lines
7.4 KiB
Markdown
# Pivot Forecast — CLAUDE.md
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## What this app is
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A web app for building named forecast scenarios against any PostgreSQL table. The workflow: load historical actuals as a baseline (optionally date-shifted into the forecast period), then apply incremental adjustments (scale, recode, clone) to build a plan. All changes are append-only, fully audited, and reversible by log entry.
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Full spec: `pf_spec.md`
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Data transport architecture options: `pf_perspective_options.md`
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UX mockup: `pf_ux_mockup.md`
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---
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## Tech stack
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- **Backend:** Node.js / Express (`server.js`)
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- **Database:** PostgreSQL — isolated `pf` schema
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- **Frontend:** React + Vite + Tailwind CSS in `ui/`; built output lands in `public/app/`
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- **Pivot:** [Perspective](https://github.com/perspective-dev/perspective) (`@perspective-dev/*` distribution, **not** FINOS `@finos/perspective`) 4.4.0 loaded from CDN at runtime — see `PERSPECTIVE.md` for config/deploy guidance
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- **Dev:** `npm run dev` (nodemon) in root; `npm run build` in `ui/`
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---
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## Project layout
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```
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server.js Express entry point; pg pool; type parsers for bigint/numeric
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routes/
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tables.js GET /api/tables, /api/tables/:schema/:tname/preview
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sources.js Source registration, col_meta, SQL generation
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versions.js Version CRUD, baseline/reference load, data stream
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operations.js scale, recode, clone, undo — the core forecast ops
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log.js GET /api/versions/:id/log, DELETE /api/log/:logid
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lib/
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sql_generator.js buildFilterClause, token substitution helpers
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utils.js
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setup_sql/
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01_schema.sql pf schema DDL — run once to install
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ui/src/
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views/
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Setup.jsx DB browser, source registration, col_meta editor
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Baseline.jsx Version management, baseline workbench, reference load
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Forecast.jsx Perspective pivot + operation panel (Scale/Recode/Clone)
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Sidebar.jsx 3-step collapsible nav
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StatusBar.jsx Source · version · row count · status
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Timeline.jsx Date-range preview bar for baseline segments
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```
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---
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## Database schema (`pf`)
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- **`pf.source`** — registered source tables
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- **`pf.col_meta`** — column roles: `dimension` | `value` | `units` | `date` | `filter` | `ignore`; `is_key` marks dimensions used in slice WHERE clauses; `dim_group` groups functionally dependent columns (e.g. date + its derived year/month dimensions); `dim_period_col` maps a dimension to a `pf.dim_period` column so date-adjacent values are derived at load time rather than copied raw
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- **`pf.version`** — named forecast scenarios; `exclude_iters` (default `["reference"]`) blocks those iter values from all operations
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- **`pf.fc_{tname}_{version_id}`** — one forecast table per version; contains both operational rows (`pf_iter = baseline|scale|recode|clone`) and reference rows (`pf_iter = reference`)
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- **`pf.log`** — audit log; every write gets one entry; `slice` + `params` stored as jsonb
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- **`pf.sql`** — generated SQL templates per source/operation; tokens substituted at request time
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- **`pf.dim_period`** — calendar lookup table (2018–2035); one row per month keyed on `sdat` (month start date); provides cal/fiscal year, quarter, and month columns; populated by `setup_sql/gen_dim_period.sql` with a configurable fiscal year start month
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### Key token substitution tokens
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`{{fc_table}}`, `{{where_clause}}`, `{{exclude_clause}}`, `{{logid}}`, `{{pf_user}}`, `{{value_incr}}`, `{{units_incr}}`, `{{pct}}`, `{{set_clause}}`, `{{scale_factor}}`, `{{date_offset}}`, `{{filter_clause}}`
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---
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## Core data flow
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### Initial load (Forecast view)
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`GET /api/versions/:id/data` → Arrow IPC binary stream → `worker.table(buffer)` in Perspective WASM
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**Why one batch (not streaming):** pg returns `bigint`/`numeric` as strings by default — type parsers in `server.js` coerce them to numbers. Per-batch Arrow encoding creates independent dictionaries that cause Perspective WASM to crash on dictionary replacement messages. Server accumulates all rows, emits one record batch.
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### Forecast operations
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POST to `/api/versions/:id/{scale|recode|clone}` → SQL executed with `RETURNING *` → new rows returned as JSON → `pspTable.update(rows)` — no full reload.
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### Undo
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`DELETE /api/log/:logid` → removes rows by logid → **full Perspective reload** (known wart).
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---
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## Slice mechanics
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When the user clicks a pivot cell, `perspective-click` fires. The handler in `Forecast.jsx` extracts `[col, '==', value]` filters from `detail.config.filter` — only `role = dimension` columns are kept as the slice. This slice populates the operation panel and is sent as the `slice` object in all operation POST bodies.
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**Limitation:** computed columns created by Perspective's split_by (e.g. Month, YearDate) don't map back to raw rows — only native dimension columns work for slice extraction.
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---
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## Operation SQL patterns
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All three operations follow the same structure: insert a `pf.log` row in a CTE, then insert forecast rows referencing its id. `{{where_clause}}` is built from the slice; `{{exclude_clause}}` blocks `exclude_iters` rows.
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- **Scale** — distributes `value_incr`/`units_incr` proportionally across rows in the slice using window functions
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- **Recode** — inserts negative rows (zero out original) + positive rows with `{{set_clause}}` dimension overrides; both share the same logid
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- **Clone** — copies the slice with `{{set_clause}}` overrides and `{{scale_factor}}` multiplier; original untouched
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`build_where()` validates every slice key against col_meta (only `role = dimension` allowed). Values are escaped but not parameterized — consistent with existing patterns, debuggable in pg logs.
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---
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## Light / dark mode
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Theme state lives in `ui/src/theme.jsx` — a React context (`ThemeContext`) with a `ThemeProvider` that wraps the app in `main.jsx`.
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- **Storage key:** `pf_dark` in `localStorage`; falls back to `window.matchMedia('(prefers-color-scheme: dark)')` on first visit
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- **Toggle:** `setDark(d => !d)` in `StatusBar.jsx`; effect writes `localStorage` and toggles the `.dark` class on `<html>`
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- **CSS:** `ui/src/index.css` defines CSS custom properties under `:root` (light) and `.dark`. All Tailwind color overrides are written as `.dark .bg-white { ... }` etc. — no Tailwind dark-mode config needed
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- **Palette:** dark mode uses Perspective's "Pro Dark" colours (`--bg-primary: #242526`, panels `#2a2c2f`, gridlines `#3b3f46`, text `#c5c9d0`)
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- **Perspective viewer:** `Forecast.jsx` calls `viewer.setAttribute('theme', dark ? 'Pro Dark' : 'Pro Light')` both on initial load and in a `useEffect([dark, versionId])` so the viewer stays in sync when the toggle fires
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- **Consuming the theme:** `import useTheme from '../theme.jsx'` then `const { dark, setDark } = useTheme()`
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## Known issues / active work
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- Operation panel (Scale/Recode/Clone) SQL generation and dim_period JOIN are complete; UI wiring to API still needs completion
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- Load progress bar is jittery — needs throttle (~10 updates/sec)
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- Default pivot layout should be configurable per source (currently hardcodes first 2 dimensions)
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- Source/version selection doesn't persist across page reload
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- Col_meta / version schema drift: if col_meta roles change after a version's forecast table is created, SQL and DDL go out of sync — workaround is to delete and recreate the version
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## Deferred (not in v1)
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Baseline replay (`replay: true` returns 501), approval workflow, territory filtering, export, version comparison, multi-DB connections.
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