update detail lineage plan

docs/plans/detail-lineage.md

@@ -98,8 +98,98 @@ partition_consumers: BTreeMap<String, Vec<String>>  // partition_ref → consume
 
 Built from read_deps on job success.
 
-## Open Questions
+## Design Decisions
 
-1. How do we visualize retries? (Same want, multiple job attempts)
-2. Should partition lineage show historical versions or just current?
-3. Performance strategy for high fan-out (partition read by 1000s of consumers)?
+1. **Retries**: List all job runs triggered by a want, collapsing retries in the UI (expandable)
+2. **Lineage UUIDs**: Resolve partition refs to canonical UUIDs at job success time (jobs don't need to know about UUIDs)
+3. **High fan-out**: Truncate to N items with "+X more" expansion
+
+## Implementation Plan
+
+### Phase 1: Data Model
+
+**1.1 Extend JobRunSuccessEventV1**
+
+```protobuf
+message JobRunSuccessEventV1 {
+  string job_run_id = 1;
+  repeated ReadDeps read_deps = 2;  // NEW: preserves impacted→read relationships
+}
+```
+
+**1.2 Extend SucceededState to store resolved UUIDs**
+
+```rust
+pub struct SucceededState {
+    pub succeeded_at: u64,
+    pub read_deps: Vec<ReadDeps>,                        // from event
+    pub read_partition_uuids: BTreeMap<String, Uuid>,    // ref → UUID at read time
+    pub wrote_partition_uuids: BTreeMap<String, Uuid>,   // ref → UUID (from building_partitions)
+}
+```
+
+UUIDs resolved by looking up canonical partitions when processing success event.
+
+**1.3 Add consumer index to BuildState**
+
+```rust
+// input_partition_ref → list of (output_partition_ref, job_run_id)
+partition_consumers: BTreeMap<String, Vec<(String, String)>>
+```
+
+Populated from `read_deps` when processing JobRunSuccessEventV1.
+
+### Phase 2: Extend Existing API Endpoints
+
+**2.1 GET /api/wants/:id**
+
+Add to response:
+- `job_runs`: All job runs servicing this want (with status, partitions built)
+- `derivative_wants`: Wants spawned by dep-miss from this want's jobs
+
+**2.2 GET /api/partitions/:ref**
+
+Add to response:
+- `built_by`: Job run that built this partition (with read_deps + resolved UUIDs)
+- `upstream`: Input partitions (refs + UUIDs) from builder's read_deps
+- `downstream`: Consumer partitions (refs + UUIDs) from consumer index
+
+**2.3 GET /api/job_runs/:id**
+
+Add to response:
+- `read_deps`: With resolved UUIDs for each partition
+- `wrote_partitions`: With UUIDs
+- `derivative_wants`: If DepMiss, the wants that were spawned
+
+### Phase 3: Frontend
+
+**3.1 Want detail page**
+
+Add "Fulfillment" section:
+- List of job runs (retries collapsed, expandable)
+- Derivative wants as nested items
+- Partition UUIDs linked to partition detail
+
+**3.2 Partition detail page**
+
+Add "Lineage" section:
+- Upstream: builder job → input partitions (navigable)
+- Downstream: consumer jobs → output partitions (truncated at N)
+
+**3.3 JobRun detail page**
+
+Add:
+- "Read" section with partition refs + UUIDs
+- "Wrote" section with partition refs + UUIDs
+- "Derivative Wants" section (if DepMiss)
+
+### Phase 4: Job Integration
+
+Extend `DATABUILD_DEP_READ_JSON` parsing to run on job success (not just dep-miss). Jobs already emit this; we just need to capture it.
+
+## Sequencing
+
+1. Proto + state changes
+2. Event handler updates
+3. API response extensions
+4. Frontend enhancements