pansy/DESIGN.md

# Pansy — Design

Pansy is a self-hostable garden planning web app. A landscaping-style 2D editor: drag garden objects (raised beds, grow bags, containers, in-ground plots, trees, paths) onto a field at real-world scale; click into a plantable object to place freeform "plops" of plants — a few plops of garlic in one corner, herbs in another, beans along a side — and zoom out to still see what's planted where. React frontend, Go backend, clean JSON API, single static binary. Works on desktop and is mobile-usable (touch drag, pinch zoom).

Work is tracked in Gitea issues; the tracking epic links every piece in dependency order.

## Decisions

- **Placement model:** freeform plops (not a square-foot grid), scaled by real plant spacing. Grid snapping may come later as a toggle.
- **Stack:** Go 1.26.x backend, module `gitea.stevedudenhoeffer.com/steve/pansy`; React + TypeScript + Vite + Tailwind frontend, production build embedded via `embed.FS` → one static binary (`CGO_ENABLED=0`).
- **Users:** multi-user with ownership. Users own gardens; a garden can be shared with other users as viewer (read) or editor (edit content). Owner additionally shares/deletes.
- **Auth:** OIDC-first (Authentik is the primary IdP), local argon2id passwords as an optional fallback.
- **Agentic future:** integration with majordomo/executus via typed Go tools (`llm.DefineTool[Args]`) wrapping the same service layer the REST API uses — not MCP/OpenAPI.

## Domain model

SQLite, centimeters everywhere (display-side imperial conversion only), `version INTEGER` on every user-mutable row for conflict detection.

- **users** — email (unique), display_name, nullable argon2id `password_hash`, nullable `oidc_issuer`+`oidc_subject` (unique pair), `is_admin`. First registered user becomes admin. `PANSY_REGISTRATION` (open/closed) gates local signup. A user can be local-password, OIDC, or both (linked by email on first OIDC login).
- **sessions** — sha256-hashed random 32-byte token, user_id, 30-day sliding expiry. HttpOnly cookie holds the raw token. Sessions are pansy-local regardless of auth method.
- **gardens** — owner_id, name, width_cm, height_cm, unit_pref (`metric`|`imperial`), notes.
- **garden_shares** — (garden_id, user_id) unique, role `viewer`|`editor`, created_by. Owner is implicit via `gardens.owner_id`, never a share row.
- **garden_objects** — one polymorphic table: `kind` (`bed`|`grow_bag`|`container`|`in_ground`|`tree`|`path`|`structure`), name, `shape` (`rect`|`circle`; `polygon` + `points` JSON reserved in schema, not in the v1 editor), center `x_cm`,`y_cm` in garden space, `width_cm`,`height_cm` (circle: width=diameter), `rotation_deg`, `z_index`, `plantable` bool, nullable `color` override, `props` JSON for kind-specific extras (bed height, tree species…), notes.
- **plants** — catalog. `owner_id NULL` = built-in (~30 seeded via migration, read-only, clone to customize). name, category (`vegetable`|`herb`|`flower`|`fruit`|`tree_shrub`|`cover`), `spacing_cm` (mature spacing), `color` hex, `icon` (emoji string — zero assets in v1), nullable `days_to_maturity`, notes. Users see built-ins + their own.
- **journal_entries** — the grow log: `garden_id` (NOT NULL), nullable `object_id`/`planting_id` to narrow the target, author, body, `observed_at`. `notes` on a garden/object/plant says what the thing IS and a new note overwrites the old; a journal entry says what HAPPENED and when, and entries accumulate. `garden_id` is set even for a bed- or plop-level entry so permission checks reuse `requireGardenRole` unchanged rather than inventing a second ACL path. `observed_at` is distinct from `created_at` — you write up Saturday's observations on Sunday. Deliberately **not** in the revision history: entries are already append-shaped and individually versioned.
- **change_sets** / **revisions** — the undo substrate. A change set groups the row-level revisions one logical operation produced (`source` ui/agent/api, `summary`, nullable `agent_run_id`, nullable `reverts_id`); a revision is `(entity_type, entity_id, op, before, after)` with full JSON row snapshots. The unit of undo is the **operation, not the row**. Revert is itself a change set, so an undo can be undone; it is version-guarded per entity and reports conflicts rather than clobbering a later edit. Garden *deletion* is deliberately not revertible (the cascade is invisible to the service, and would take the history with it).
- **plantings** ("plops") — object_id, plant_id, center `x_cm`,`y_cm` **in the parent object's local frame** (moving/rotating a bed moves its plants for free), `radius_cm` (a plop is a circular patch), nullable `count` (NULL = derived: `max(1, round(π·r² / spacing_cm²))`), nullable label, `planted_at`/`removed_at` dates. "Clear bed" sets `removed_at`; v1 shows rows where `removed_at IS NULL`. Year-over-year history and a future plan/scenario layer build on these dates without schema surgery.

## Geometry

- Garden space: origin top-left, x→right, y→down (screen-aligned), cm.
- Objects: positioned by **center point** + `rotation_deg` clockwise about center → SVG `translate(x y) rotate(deg)` one-liners.
- Object local frame: origin at object center, axes aligned to the unrotated object. Plops live in this frame.
- Exactly two nesting levels: garden → object → plop. No recursive containers.
- API and DB are metric-only; cm ↔ ft/in conversion is purely a frontend display concern.

## Editor / rendering

- **Plain SVG in React.** Tens of objects + low-hundreds of plops is far below SVG's ceiling; native DOM hit-testing, Tailwind styling, crisp text at any zoom. No Konva/canvas.
- **One gesture library: `@use-gesture/react`** for unified drag / wheel-zoom / pinch on desktop + touch. Everything else is hand-rolled pointer math.
- Viewport = a single `<g transform="translate(tx,ty) scale(s)">`; state `{tx, ty, scale}` where scale = px per cm. Wheel/pinch zooms to cursor; drag on empty space pans; drag on an element moves it.
- **Field view and bed interior are the same canvas.** "Click into a bed" animates the viewport to fit the object and sets `focusedObjectId` (mirrored to `?focus=` URL param for deep links). Focused mode dims siblings and enables plop placement; Escape/tap-out zooms back.
- **Semantic zoom**, three bands by scale (thresholds tuned by feel):
  - zoomed out (< ~0.75 px/cm): plops render as flat color patches; plantable objects show name + dominant-plant color — "what's planted where" at a glance;
  - mid: plops as colored circles with the plant's emoji icon;
  - zoomed in (> ~3 px/cm): icon + plant name + count per plop.

## API

REST under `/api/v1`, JSON, cookie-session auth (HttpOnly, SameSite=Lax, Secure under TLS). Gin with slog-gin + Recovery; embedded SPA fallback for non-`/api` routes.

```
POST /auth/register | /auth/login | /auth/logout     GET /auth/me      GET /auth/providers
GET  /auth/oidc/login      GET /auth/oidc/callback   (authorization-code + PKCE)
GET,POST /gardens                                    GET,PATCH,DELETE /gardens/:id
GET  /gardens/:id/full        ← one-shot editor load: garden + objects + plantings + referenced plants
GET  /gardens/:id/history     ← change sets, newest first (paginated)
POST /change-sets/:id/revert  ← undo an operation; 201, or 409 + the conflicts it skipped
POST /gardens/:id/copy        ← deep-copy a garden you own (objects + active plops; not shares/link)
POST /gardens/:id/objects     PATCH,DELETE /objects/:id
POST /objects/:id/plantings   PATCH,DELETE /plantings/:id
GET,POST /plants              PATCH,DELETE /plants/:id            (own plants only)
GET,POST /gardens/:id/shares  PATCH,DELETE /gardens/:id/shares/:userId    (invite by email)
```

**Sync:** plain REST + optimistic UI + last-write-wins with a version guard. Every PATCH/DELETE carries the row's `version`; the server increments on write and returns **409 + the current row** on mismatch; the client rolls back and refetches. No websockets/CRDT — the right cost for household-scale co-editing. Drags PATCH once on drop, not per frame.

## Backend layout

**Storage:** `modernc.org/sqlite` (pure Go) + hand-written SQL via `database/sql`. WAL mode + `busy_timeout=5000` (open pattern per executus `contrib/store/sqlite.go`). Migrations are numbered `.sql` files in an `embed.FS` with a tiny runner and a `schema_migrations(version)` table, run at startup; seed plants live in a migration.

```
cmd/pansy/main.go        config load → store.Open → migrate → service → api → ListenAndServe
internal/config/         PANSY_PORT, PANSY_DB, PANSY_BASE_URL, PANSY_REGISTRATION,
                         PANSY_OIDC_* (issuer/client_id/secret/button label), PANSY_LOCAL_AUTH,
                         trusted proxies
internal/store/          sqlite.go (open/pragmas), migrate.go, migrations/*.sql (embedded),
                         queries per entity (users.go, gardens.go, objects.go, plantings.go,
                         plants.go, shares.go)
internal/domain/         plain structs + sentinel errors (ErrNotFound, ErrForbidden,
                         ErrVersionConflict)
internal/service/        ★ THE SEAM. All permission checks + business ops. auth.go, gardens.go,
                         objects.go, plantings.go, plants.go, shares.go, ops.go (FillRegion etc.),
                         revisions.go (change-set scoping, recording, revert)
internal/api/            thin gin handlers (decode → service → encode), session middleware,
                         ginserver setup, routes.go, oidc.go, spa.go (embed fallback)
internal/webdist/        dist.go: //go:embed all:dist   (web build copied in by Makefile)
internal/agent/          later: llm.DefineTool[Args] wrappers over the SAME service methods
web/                     Vite app
Makefile                 (cd web && npm run build) → copy dist → CGO_ENABLED=0 go build
```

**Every mutation is recorded.** Service mutations call `record(...)`, which joins the change set on the context if one is open and otherwise opens a single-op one for that mutation alone. That auto-scope is what keeps undo shallow: REST handlers need no changes at all, and only the agent wraps a whole turn (`WithChangeSet`) so a multi-step turn undoes as one unit. A multi-row operation passes all its changes in one `record` call for the same reason.

**The service seam is the point.** Every operation is a method on `*service.Service` taking `(ctx, actorUserID, args)`; all ACL checks live there, not in handlers. REST handlers are thin adapters; future agent tools are equally thin `llm.DefineTool[Args]` adapters over the same methods — so agent calls inherit permission enforcement for free. Bulk ops designed for agents from the start, e.g. `FillRegion(ctx, actor, objectID, region, plantID, spacingOverride)` with `region` a rect/circle in object-local coordinates.

### Auth

- **OIDC (primary; Authentik).** `github.com/coreos/go-oidc/v3` + `golang.org/x/oauth2` (pure Go). Authorization-code flow with PKCE + `state` cookie; issuer discovery from `PANSY_OIDC_ISSUER`; redirect URI derived from `PANSY_BASE_URL`. JIT provisioning on first login (the IdP gates access, so the registration flag doesn't apply); the email claim links to an existing local account if one matches, otherwise a user is created and stamped with `oidc_issuer`/`oidc_subject`.
- **Local (fallback).** argon2id (`x/crypto/argon2`, id variant), `subtle.ConstantTimeCompare`. Disable entirely with `PANSY_LOCAL_AUTH=false` for pure-Authentik deployments.
- Both paths end in the same pansy session cookie. `GET /auth/providers` tells the login page which methods to show.

## Frontend layout

React 19 + TypeScript + Vite + Tailwind 4 (`@tailwindcss/vite`), `@tanstack/react-router`, `@tanstack/react-query`, zod for API parsing; dev proxy `/api` → Go server.

- **Routes:** `/login`, `/register`, `/gardens` (list), `/gardens/:id` (editor, `?focus=objectId`), `/plants` (catalog). Auth guard on the router root via `/auth/me`.
- **State:** TanStack Query for all server state (editor keyed on `gardens/:id/full`; optimistic mutations with version-conflict rollback). One small Zustand store for ephemeral editor state only: viewport, selection, focused object, active tool, in-flight drag.
- **Editor components (`web/src/editor/`):** `GardenCanvas` (svg root + viewport g), `useViewport` (use-gesture pan/zoom/pinch), `ObjectShape`, `PlopMarker` (semantic-zoom branching), `Palette` (drag-to-place object kinds), `EditorRail` (the one side panel), `Inspector`, `HistoryPanel`, `PlantPicker`.
- **One rail, tabs inside it.** The inspector, history, and later the journal and chat panel all want the same strip of screen; rather than each bolting on its own chrome they are tabs in `EditorRail` — so the canvas is one width instead of a different width per panel, and adding a panel is adding a tab. Selecting an object switches to the Inspector tab automatically, so the rail is never something you operate before you can edit; on a phone the same tabs render in the bottom sheet the inspector already used. Pure geometry helpers (local↔world transforms, unit formatting) in `web/src/lib/geometry.ts`, unit-tested.

## Roadmap

1. **Scaffold** — Go module, config, gin server, healthz, sqlite + migration runner; Vite/Tailwind/router shell; embed.FS single-binary build.
2. **Auth** — OIDC (Authentik) + local fallback, sessions, route guard.
3. **Gardens** — CRUD + list page; establishes service-layer and version/409 conventions.
4. **Field editor** — objects, canvas, pan/zoom/pinch, palette, move/resize/rotate, optimistic sync. *Riskiest slice — test on a phone at the end of it, not later.*
5. **Plant catalog** — ~30 seeded built-ins + custom plants.
6. **Plops** — focus-zoom, place/move/resize, derived counts, semantic zoom. *The core vision lands here.*
7. **Sharing** — invite by email, roles, viewer read-only mode.
8. **Polish** — imperial toggle, mobile ergonomics, clear-bed, keyboard nudging.
9. **Agent seam** — `ops.go` bulk ops + `internal/agent` DefineTool wrappers; optional mort-style API-key agent endpoint. The agent harness itself lives in majordomo/executus, outside pansy.

## Deliberate v1 limits

1. Plop `count` derived from area ÷ spacing², explicit override allowed.
2. Shapes: rect + circle only (polygon reserved in schema).
3. Seasons = planted/removed dates; a scenario/year-plan layer is future work these dates don't block.
4. Emoji plant icons (zero assets); SVG icon set later if wanted.
5. No background/satellite image tracing (cheap to add later as a garden background field).
6. 409-and-refetch conflict handling; no real-time sync.