Appendix: Workspace Scaffold

The finished workspace, annotated with the chapter that creates each file. The dependency arrow always points toward etl-core; only the binary names concrete sources.

The tree

panoptes_etl/
├── Cargo.toml                         # workspace manifest        (Part II)
├── crates/
│   ├── etl-core/                      # the seams — depends on nothing in-workspace
│   │   ├── Cargo.toml
│   │   └── src/
│   │       ├── lib.rs                 # module wiring + re-exports
│   │       ├── error.rs               # EtlError taxonomy         (Part I)
│   │       ├── ids.rs                 # NoradId newtype           (Part I)
│   │       ├── domain.rs              # SpaceObject/OrbitalElements/Conjunction/Launch (Part I–III)
│   │       ├── pipeline.rs            # Source/Transform/Sink, RawRecord, Row (Part II)
│   │       ├── sink_jsonl.rs          # JsonlSink — the file contract (Part II)
│   │       ├── ledger.rs              # RunRecord/Outcome/Ledger  (Part III)
│   │       ├── retry.rs               # with_retry, RetryPolicy   (Part IV)
│   │       ├── content.rs             # content_id, IdempotentSink (Part IV)
│   │       ├── embed.rs               # Embedder trait            (Part VI)
│   │       └── vector.rs              # cosine, VectorIndex, EmbedSink (Part VI)
│   ├── etl-sources/                   # concrete sources — depends on etl-core
│   │   ├── Cargo.toml
│   │   └── src/
│   │       ├── lib.rs
│   │       ├── tle.rs                 # hand-rolled TLE parser    (Part II)
│   │       ├── celestrak.rs           # CelestrakSource/Transform (Part II)
│   │       ├── http.rs                # classify_status taxonomy funnel (Part II–III)
│   │       ├── limiter.rs             # TokenBucket               (Part III)
│   │       ├── spacetrack.rs          # SpaceTrackSource/Transform (Part III)
│   │       ├── spacedevs.rs           # SpaceDevsSource/Transform (Part IV)
│   │       └── voyage.rs              # VoyageEmbedder            (Part VI)
│   ├── etl-orchestrate/               # the DAG executor — depends on etl-core ONLY
│   │   ├── Cargo.toml
│   │   └── src/
│   │       ├── lib.rs
│   │       ├── graph.rs               # Dag, TaskId, topological_order (Part V)
│   │       └── executor.rs            # Pipeline, Executor, RunReport (Part V)
│   └── panoptes-etl/                  # the binary — the only crate naming concrete sources
│       ├── Cargo.toml
│       └── src/
│           ├── main.rs                # wiring + build_executor   (Part V)
│           └── cli.rs                 # clap surface + status     (Part V)
└── data/                             # gitignored ETL output (JSONL) + runs.jsonl ledger

The workspace manifest

[workspace]
resolver = "2"
members = ["crates/etl-core", "crates/etl-sources", "crates/etl-orchestrate", "crates/panoptes-etl"]

[workspace.dependencies]
serde = { version = "1", features = ["derive"] }  # derive on the domain model
serde_json = "1"                                   # JSONL wire format
chrono = { version = "0.4", features = ["serde"] } # epochs, TCA, watermarks
thiserror = "2"                                     # the EtlError taxonomy (libs)
anyhow = "1"                                        # the binary's error type
async-trait = "0.1"                                 # dyn-compatible async traits
tokio = { version = "1", features = ["full"] }      # runtime, fs, time
reqwest = { version = "0.12", features = ["json"] } # HTTP client
clap = { version = "4", features = ["derive"] }     # CLI
sha2 = "0.10"                                        # content-addressing
itertools = "0.13"                                   # iterator helpers
wiremock = "0.6"                                      # mock every live API (dev)
pretty_assertions = "1"                               # readable test diffs (dev)

Per-crate dependency matrix

The empty etl-orchestrate → reqwest / etl-sources cells are the point: the executor cannot reach a concrete source. cargo tree -p etl-orchestrate shows only etl-core (+ chrono/serde). That is the dependency-inversion seam, enforced by the build, not by convention.

Expected test progression

Cumulative workspace test count after each part (run cargo test):

Final workspace: 65 tests — etl-core 29, etl-sources 26, etl-orchestrate 7, panoptes-etl 3 — clippy clean.