vyndr/BACKEND_HANDOFF.md

# VYNDR — Backend / Frontend Data Contract (BACKEND_HANDOFF.md)

**Canonical frontend↔backend data contract for the Player Intelligence System.**
Every future session references this. Authored Session 44 from the shipped
implementation (Sessions 42–44). When an endpoint or component shape changes,
update this file in the same commit.

> Naming: archetypes are **VYNDR Originals** (TORCH, BOMBER, ALPHA, …). The old
> descriptive labels live on each archetype as `legacyName` and are NEVER shown.

---

## 1. Archetypes (`src/services/archetypeService.js`)

`classify(sport, stats) → { sport, primary, secondary|null, blend }`

```
primary | secondary : {
  name, legacyName, tag, sport, color (#hex), glyph (key),
  description, propDNA: { reliable: string[], volatile: string[] }, education
}
blend : [{ archetype: <NAME>, weight: 0..1 }]   // normalized, top 4, sums ~1
```

**Roster (41):** see `ARCHETYPES` registry. Colors are unique *within* a sport,
reused *across* sports. Frontend visual map (color/glyph/desc) is mirrored in
`web/src/lib/archetypes.js` — keep colors identical (a test enforces it).

- **NBA (15):** TORCH, CONDUCTOR, FORTRESS, ARTILLERY, SURGE, DUAL THREAT,
  CONNECTOR, FASTBREAK, PAINT BOSS, LOCKDOWN, SWITCHBOARD, ARCHITECT, PISTON,
  SENTINEL, IGNITER
- **WNBA-unique (5):** DISTRIBUTOR, SHIELD, RANGE, SPARK, ANCHOR (plus reused NBA)
- **MLB (15):** BOMBER, BRUSH, DRIVER, ALPHA, WHIFF, GHOST, HYBRID, FLEX,
  WORKHORSE, CATALYST, MIRROR, HAMMER, SINKER, BRIDGE, SWITCH
- **Soccer (6):** FINISHER, MAESTRO, TOWER, MOTOR, BLADE, WALL

Classifier input shapes:
- NBA/WNBA: `{ ppg, rpg, apg, bpg, spg, threes, usg, fg3a, pos, bench }`
- MLB hitter: `{ avg, hr, rbi, sb, ops, runs, k_rate, doubles }`
- MLB pitcher: `{ era, k9, whip, ip_per_start, saves, role: 'SP'|'RP'|'CL' }`

---

## 2. Stats API (`src/routes/stats.js`, mounted at `/api/stats`)

All player-intelligence endpoints are public, rate-limited 60/min, and ALWAYS
return 200 with a valid (possibly empty) shape — the UI must never hard-fail.
Browser must hit the **Next proxy** under `web/src/app/api/stats/...`, never
Express directly.

### `GET /api/stats/player/:name?sport=nba`
```
{
  player, sport, team, found: boolean,
  archetype: { primary, secondary, blend },     // §1
  propDNA: { reliable, volatile },
  education: string,
  season:  [{ k, v, lg? }],                      // display rows (mono)
  last10:  [{ d, opp, res?, stat }],
  splits:  [{ k, a, b }],
  gradeHistory: [{ grade, prop, hit?, miss? }],
  activeProps:  [{ stat, line, side: 'O'|'U', grade, confidence }],
  intel: [{ label, kind: 'form'|'grade'|'plain', value, score?, color }],
  injury: { label, note, cascade } | null
}
```
`found` is true when real season stats OR tonight's graded props exist. MLB stats
come from `mlbStatsAdapter.getPlayerStats(name)`; NBA/WNBA from `nbaStatsClient`
(degrades to `found:false` when the Python service is offline).

### `GET /api/stats/leaders?sport=mlb&stat=hits&limit=10`
```
{ sport, stat|null, leaders: [{ player, team, stat, line, side, grade, confidence }] }
```
Source: the `grades:{sport}` cache (tonight's graded slate, by confidence desc).

### `GET /api/stats/game/:id?sport=nba`
ESPN game summary (injuries, leaders, ESPN Bet odds, box score) or `{error}`.

### `GET /api/stats/lineup/:team?sport=mlb`  (Session 43)
`{ sport, team, lineup: [{ player, position, battingOrder, projectedMinutes }] }`
MLB returns the probable starting pitcher from the schedule.

### `GET /api/stats/depth/:team?sport=nba`
`{ sport, team, positions: [{ position, starter, backup, thirdString }] }`

### `GET /api/stats/cascade/:player?sport=nba&team=SA`
`{ sport, player, cascade: [{ player, stat, delta: '+x%', reason }] }`
Usage redistribution weighted by archetype (SURGE benefits most).

---

## 3. Grade Result Card (`web/src/components/vyndr/GradeResultCard.tsx`)

`GradeResultData` (built by `web/src/lib/gradeAdapter.js` `mapScanToGradeResult`):
core fields (player, team, sport, stat, line, side, grade, confidence, edge,
projection, signals[], killConditions[], books[], altLadder[]) **plus** optional
Player-Intelligence fields that self-hide when absent:
```
archetypeBlend?: [{ archetype, weight }]
propDNA?:        { reliable: string[], volatile: string[] }
statContext?:    { season?, last10?, vsOpp? }
vyndrIntel?:     { form?, usage?, matchup?, rest? }
```
The engine (`analyzeViaEngine1`) attaches snake_case fields
(`season_avg`/`last10_avg`/`form`/`usage`/`matchup_grade`/`rest`, and when a
season line is available, `archetype`/`archetype_blend`/`prop_dna`); the adapter
maps them in. Archetype at grade time requires a multi-stat season line — until
the snapshot pipeline supplies it, the archetype strip stays hidden.

---

## 4. Game Card (`web/src/components/vyndr/GameCard.tsx`)

`GameCardData` core (id, sport, away/home, time, venue, lines[], …) **plus**:
```
playerStrips?: [{ player, team, archetype?: {primary, secondary?}, stats: [{label,value}], props: [{stat,line,side,grade}] }]
pitchers?:     { away: {name, era, archetype?}, home: {name, era, archetype?} }
```
Built by `slateAdapter.mapScheduleToGameCards` (`groupPropsByPlayer` +
`mapPitchers`). The card prefers `playerStrips` (name once, horizontal) over
legacy per-prop rows. Book chips use `web/src/lib/books.js` brand colors.

---

## 5. Stat Strip (`web/src/components/vyndr/StatStrip.tsx`)

`compact` (game cards) | `expanded` (profile hero / grade result). HARD RULE: the
player name appears ONCE; stats flow horizontally in JetBrains Mono. Props render
inline with `GradeBadge`. `onPlayerClick` → `/player/:name?sport=` (`lib/playerHref.js`).

---

## 6. Freshness & caching

- Schedule cache TTL ≤ 30 min (`scheduleService`). Frontend filters completed
  games older than 24h out of the slate (`slateAdapter.isRelevantGame`).
- Player props: PropLine primary (3-key rotation), The-Odds-API backup.
- `grades:{sport}` cache (TTL 2h) is written by `gradeSlateService` on a fresh
  odds fetch; it feeds `/leaders` + the player card's `activeProps`.