---
title: "Sprint 2 — Server Briefing"
description: "Shadowcasting algorithm, vision cone implementation, ObserverSnapshot v2 schema"
type: sprint
status: archived
sprint: 2
team: "server"
---

# Sprint 2: See — Server Tasks

**Goal:** Fog of perception working through the bridge — server computes LOS visibility, client renders fog.

**Branch:** `server`
**Agents:** Dudley (simulation), Oscar (networking)

## Design Tasks

| # | Title | Blocked by |
|---|-------|------------|
| #359 | Resolve Q-018: shadowcasting algorithm selection | — |
| #358 | Design ObserverSnapshot v2 schema | — |

## Implementation Tickets

| # | Title | Blocked by |
|---|-------|------------|
| #110 | Shadowcasting algorithm - server | #359 (algorithm decision) |
| #111 | Vision cone implementation | #110 |
| #112 | Observer visibility query | #111, #358, #361, #362 |
| #25 | Game clock and day-phase system | #358 (snapshot schema) |

## Knowledge Graph Tickets (from Workshop #351, D-041)

| # | Title | Priority | Est. | Blocked by |
|---|-------|----------|------|------------|
| #361 | Implement KnowledgeGraph component + types | critical | 1d | — |
| #362 | StableEntityId + EntityRegistry resource | critical | 1d | — |
| #363 | KnowledgeEventQueue + processing system | high | 0.5d | — |
| #364 | Direct observation knowledge flow | critical | 0.5d | — |
| #365 | Basic knowledge decay system | high | 0.5d | — |
| #367 | Knowledge graph unit test suite | high | 1d | — |

**Start #361 and #362 on day 1.** Both block #112 (observer visibility query). See `decisions/architecture.md` D-041 for canonical struct definitions.

Use `db/connectors/ticket show <id>` for full details.

## Key Decisions

- `decisions/perception.md` — D-011 (fog non-negotiable), D-015 (locked camera + vision cone), D-018 (three-range sound model)
- `decisions/architecture.md` — D-010 (information boundaries), D-020 (ObserverSnapshot), D-031 (time system), D-041 (Knowledge Graph Data Model)
- `docs/workshops/knowledge-graph-information-boundaries/round2-synthesis.md` — canonical reference for knowledge graph structs and Sprint 2 scope

## Open Questions to Resolve Early

- **Q-018 (#359):** Shadowcasting algorithm selection — symmetric (Albert Ford) vs recursive. Needs benchmarking at 150x150 scale. Resolve before #110 starts.
- **Q-019 (#360):** Entity ID stability — how `entity_id: u64` maps to bevy `Entity`. Affects client entity lifecycle. (Joint ticket, blocks #130.)
- **Q-021:** Tick budget overflow policy — what happens when a tick exceeds 100ms. (Not yet ticketed.)

## Notes

- **#236 (Sprint 1, done):** `WalkabilityMap` and `validate_movement` are implemented (`server/src/simulation/movement.rs`). Walls are both collision barriers AND LOS occluders — the shadowcasting system reads the walkability map (or a parallel opacity map) to determine what blocks vision.
- **#110:** Core of the sprint. Implement LOS calculation per z-level. Output: set of visible tiles for a given observer position.
- **#111:** Vision cone sectors (forward/peripheral/behind per D-015). Facing direction component needed. Forward = full LOS range, peripheral = reduced range + dimmer, behind = blind. The cone modulates the shadowcast output.
- **#112:** Given an observer entity, return visible entities and tiles. This is the system that populates `ObserverSnapshot.entities` with only what the observer can see. Currently the snapshot includes ALL entities (no filtering). This ticket adds the filter.
- **#25:** `SimulationTime` already exists (`server/src/simulation/time.rs`) with tick/pause/day-phase. Remaining: include time data in `ObserverSnapshot` so the client can display it. May also need `FacingDirection` component for vision cone.
- **ObserverSnapshot expansion:** The `ObserverSnapshot` struct (`server/src/bridge/types.rs`) needs new fields: `visible_tiles: Vec<VisibleTile>` (or bitmap), `player_facing: Direction`, `game_time: TimeData`. Design this before implementation starts.

## Dependency Chain

```
#359 (Q-018) → #110 (shadowcast) → #111 (vision cone) ──┐
#361 (KnowledgeGraph) ─┬─→ #112 (observer query) → ...  │
#362 (StableEntityId) ─┘                                  │
#358 (snapshot v2) → #112, #113, #25  ────────────────────┘
#25 (time) → parallel track, blocked by #358

Knowledge graph parallel track:
#361, #362 (day 1-3, no blockers) → #363, #364 (day 3-4) → #365, #367 (parallel)
```

## PR Workflow

When ready to submit, create a PR with `tea` CLI. **All flags are required** to avoid TTY prompts (see CLAUDE.md "Gitea access" section):
```bash
tea pr create --repo jpmschweitzer/settled-reach --login schweitz --title "feat(simulation): description" --description "body" --base main --head server
```