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+# NEO-59 — Implementation plan
+
+## Story reference
+
+| Field | Value |
+|--------|--------|
+| **Key** | NEO-59 |
+| **Title** | E3.M1: Resource node definition registry + DI |
+| **Linear** | https://linear.app/neon-sprawl/issue/NEO-59/e3m1-resource-node-definition-registry-di |
+| **Module** | [E3.M1 — ResourceNodeAndGatherLoop](../decomposition/modules/E3_M1_ResourceNodeAndGatherLoop.md) · Epic 3 Slice 2 · backlog **E3M1-03** |
+| **Branch** | `NEO-59-e3m1-resource-node-definition-registry-di` |
+| **Precursor** | [NEO-58](https://linear.app/neon-sprawl/issue/NEO-58) — fail-fast `ResourceNodeCatalog` load (**merged** to `main` via PR #93) |
+| **Pattern** | [NEO-52](https://linear.app/neon-sprawl/issue/NEO-52) — thin registry adapter over startup catalog + DI; strict split after NEO-58 loader |
+
+## Kickoff clarifications
+
+| Topic | Question | Agent recommendation | Answer |
+|--------|----------|----------------------|--------|
+| **Enumeration API** | Include `GetDefinitionsInIdOrder()` now? | **Yes** — mirror `IItemDefinitionRegistry` / `ISkillDefinitionRegistry`; [NEO-60](https://linear.app/neon-sprawl/issue/NEO-60) `GET /game/world/resource-node-definitions` will need ordered defs without reaching into `ResourceNodeCatalog`. | **User:** include enumeration. |
+| **Yield access** | How should yield rows be exposed? | **Separate `TryGetYield(nodeDefId)`** alongside `TryGetDefinition` — mirrors `ResourceNodeCatalog.TryGetNode` / `TryGetYield`; backlog E3M1-03 tests call for yield metadata + capacity (`maxGathers`) fields. | **User:** separate `TryGetYield`. |
+| **Lookup naming** | `TryGetDefinition` vs `TryGetNode`? | **`TryGetDefinition(string? nodeDefId, …)`** — same naming as item/skill registries; catalog keeps `TryGetNode` for direct catalog access. | **Adopted** — NEO-52 / NEO-58 precedent. |
+| **Program.cs eager resolve** | Eager-resolve `IResourceNodeDefinitionRegistry` at boot? | **Omit** — `ResourceNodeCatalog` is already eager-resolved in `Program.cs` (NEO-58); registry is a thin adapter (NEO-52 default). | **Adopted** |
+| **Runtime validation** | Re-validate nodes/yields in registry? | **No** — catalog load is fail-fast (NEO-58); registry delegates to loaded rows only. | **Adopted** |
+
+## Goal, scope, and out-of-scope
+
+**Goal:** Provide **`IResourceNodeDefinitionRegistry`** backed by the startup-loaded **`ResourceNodeCatalog`**: resolve node defs and yield rows by stable **`nodeDefId`**, enumerate node defs in id order, expose prototype metadata (`displayName`, `gatherLens`, `maxGathers`, yield `itemId` / `quantity`). Register in DI so **NEO-60+** (HTTP), **NEO-61** (depletion), **NEO-62** (gather engine), and interact wiring depend on the interface instead of the catalog type.
+
+**In scope (from Linear + [E3M1-03](E3M1-prototype-backlog.md#e3m1-03--resource-node-definition-registry--di)):**
+
+- `ResourceNodeDefinitionRegistry` thin adapter over `ResourceNodeCatalog`.
+- DI registration alongside existing catalog singleton.
+- Unit tests (AAA): known prototype id lookup + node metadata + yield metadata; unknown `nodeDefId` returns false without throwing; enumeration order; host resolves registry from DI.
+
+**Out of scope (from Linear + backlog):**
+
+- HTTP ([NEO-60](https://linear.app/neon-sprawl/issue/NEO-60)).
+- Persistence of depletion state ([NEO-61](https://linear.app/neon-sprawl/issue/NEO-61)).
+- Gather engine / inventory mutation ([NEO-62](https://linear.app/neon-sprawl/issue/NEO-62)).
+- Changing loader, Slice 2 gate, or catalog load semantics (NEO-58).
+
+## Acceptance criteria checklist
+
+- [ ] DI resolves `IResourceNodeDefinitionRegistry` at host startup (test via `InMemoryWebApplicationFactory`).
+- [ ] Unit tests (AAA): lookup for known prototype `nodeDefId` (e.g. `prototype_resource_node_alpha`) with expected node metadata (`gatherLens`, `maxGathers`) and yield metadata (`itemId`, `quantity`).
+- [ ] Unit tests (AAA): unknown `nodeDefId` returns false / absent without throwing (both node and yield lookups).
+- [ ] `GetDefinitionsInIdOrder` returns all loaded node defs ordered by `nodeDefId` (ordinal).
+
+## Technical approach
+
+1. **`IResourceNodeDefinitionRegistry`** — mirror [`IItemDefinitionRegistry`](../../server/NeonSprawl.Server/Game/Items/IItemDefinitionRegistry.cs):
+   - `TryGetDefinition(string? nodeDefId, [NotNullWhen(true)] out ResourceNodeDefRow? definition)` — null and unknown ids return false without throwing.
+   - `TryGetYield(string? nodeDefId, [NotNullWhen(true)] out ResourceYieldRow? yield)` — same contract for yield rows.
+   - `GetDefinitionsInIdOrder()` — all node defs ordered by `ResourceNodeDefRow.NodeDefId` (ordinal).
+   - XML remarks: gather engine / depletion / interact callers (NEO-61+) should use this interface; HTTP read model (NEO-60) should not reach into `ResourceNodeCatalog`.
+
+2. **`ResourceNodeDefinitionRegistry`** — primary-constructor adapter over `ResourceNodeCatalog` (same pattern as [`ItemDefinitionRegistry`](../../server/NeonSprawl.Server/Game/Items/ItemDefinitionRegistry.cs)).
+
+3. **DI** — extend [`AddResourceNodeCatalog`](../../server/NeonSprawl.Server/Game/Gathering/ResourceNodeCatalogServiceCollectionExtensions.cs) to register `IResourceNodeDefinitionRegistry` → `ResourceNodeDefinitionRegistry` after catalog registration. No change to `Program.cs` eager-resolve (catalog only).
+
+4. **Comments** — update `ResourceNodeCatalog` summary to point at `IResourceNodeDefinitionRegistry`; update [server README](../../server/README.md) resource-node catalog section (currently says “lands in NEO-59”).
+
+5. **Tests** — new `ResourceNodeDefinitionRegistryTests.cs` mirroring [`ItemDefinitionRegistryTests`](../../server/NeonSprawl.Server.Tests/Game/Items/ItemDefinitionRegistryTests.cs): in-memory catalog helper, loader-backed prototype fixture via `ResourceNodeCatalogTestPaths`, host DI test.
+
+## Files to add
+
+| Path | Purpose |
+|------|---------|
+| `server/NeonSprawl.Server/Game/Gathering/IResourceNodeDefinitionRegistry.cs` | Public contract: node lookup, yield lookup, enumerate, remarks for NEO-60/61/62 callers. |
+| `server/NeonSprawl.Server/Game/Gathering/ResourceNodeDefinitionRegistry.cs` | Singleton adapter over `ResourceNodeCatalog`. |
+| `server/NeonSprawl.Server.Tests/Game/Gathering/ResourceNodeDefinitionRegistryTests.cs` | AAA unit + host DI tests (mirror `ItemDefinitionRegistryTests`). |
+
+## Files to modify
+
+| Path | Rationale |
+|------|-----------|
+| `server/NeonSprawl.Server/Game/Gathering/ResourceNodeCatalogServiceCollectionExtensions.cs` | Register `IResourceNodeDefinitionRegistry` → `ResourceNodeDefinitionRegistry` after catalog singleton. |
+| `server/NeonSprawl.Server/Game/Gathering/ResourceNodeCatalog.cs` | Tighten summary comment to reference `IResourceNodeDefinitionRegistry` (replace “Prefer registry in NEO-59” placeholder). |
+| `server/README.md` | Resource-node catalog section: document `IResourceNodeDefinitionRegistry` as preferred lookup surface. |
+| `docs/decomposition/modules/documentation_and_implementation_alignment.md` | E3.M1 row — note NEO-59 registry when landed. |
+
+## Tests
+
+| Test file | What it covers |
+|-----------|----------------|
+| `server/NeonSprawl.Server.Tests/Game/Gathering/ResourceNodeDefinitionRegistryTests.cs` | **Unit:** `TryGetDefinition` for `prototype_resource_node_alpha` returns true with `GatherLens`, `MaxGathers`, `DisplayName`; `TryGetYield` for same id returns true with `ItemId` (`scrap_metal_bulk`) and `Quantity`; null and unknown id return false without throw for both methods; `GetDefinitionsInIdOrder` count (4) and ordinal order for multi-node fixture; loader-backed prototype fixture matches catalog. **Host:** `InMemoryWebApplicationFactory` resolves `IResourceNodeDefinitionRegistry` and finds `prototype_resource_node_alpha` with expected yield. |
+
+## Open questions / risks
+
+| Question / risk | Agent recommendation | Status |
+|-----------------|----------------------|--------|
+| **Catalog vs registry for game code** | New callers inject `IResourceNodeDefinitionRegistry`; leave `ResourceNodeCatalog` eager-resolve in `Program.cs` for fail-fast only. | **adopted** |
+| **Duplicate API on catalog** | Keep `ResourceNodeCatalog.TryGetNode` / `TryGetYield` for loader/tests; registry is the game-facing surface (NEO-52 precedent). | **adopted** |
+| **NEO-60 HTTP projection** | API layer joins node + yield via registry’s two TryGet methods when building DTOs; no combined read model in NEO-59. | **adopted** |
+
+## Decisions (kickoff)
+
+- **`GetDefinitionsInIdOrder()` included** — enumeration for NEO-60 HTTP without catalog coupling.
+- **Separate `TryGetYield`** — yield metadata available to gather engine / tests without a combined DTO.
+- **`TryGetDefinition` naming** — consistent with item/skill registries; parameter is `nodeDefId`.
+- **No `Program.cs` registry eager-resolve** — catalog fail-fast only (NEO-52 pattern).