Appendix: Workspace Scaffold

This is the orientation map for the harness workspace you are building (a separate repo from this book). It answers three questions the build chapters assume: where does each file go, what is it called, and which dependencies does it need? Every build chapter also carries its own Scaffold block; this page is the whole picture in one place.

The harness workspace is its own project directory (e.g. ~/projects/rust/panoptes/) — do not create it inside this course's repo.

The full tree

Everything you create across the course, annotated with the chapter that creates it:

panoptes/
├── Cargo.toml                         # workspace manifest        (Part II · build-params)
├── crates/
│   ├── panoptes-core/                 # THE DATA MODEL — no I/O, no network, pure types
│   │   ├── Cargo.toml                 #                           (Part II · build-params)
│   │   └── src/
│   │       ├── lib.rs                 # re-exports                (Part II, grows each chapter)
│   │       ├── params.rs              # Params + parameter enums  (Part II · build-params)
│   │       ├── codes.rs               # codebook enums + CodedRow (Part II · build-codes)
│   │       ├── vignette.rs            # Vignette, vignette_id     (Part II · build-records)
│   │       └── record.rs              # ResponseRecord, Usage     (Part II · build-records)
│   ├── panoptes-gen/                  # STAGE 1 — generation
│   │   ├── Cargo.toml                 #                           (Part III · build-family)
│   │   └── src/
│   │       ├── lib.rs                 #                           (Part III · build-family)
│   │       ├── family.rs              # FamilySpec (TOML shape)   (Part III · build-family)
│   │       ├── validity.rs            # ScenarioFamily trait      (Part III · build-family)
│   │       ├── generate.rs            # grid → Vec<Vignette>      (Part III · build-generate)
│   │       └── main.rs                # `panoptes-gen` binary     (Part III · build-cli)
│   ├── panoptes-harness/              # STAGE 2 — execution
│   │   ├── Cargo.toml                 #                           (Part IV · build-client-log)
│   │   └── src/
│   │       ├── lib.rs                 #                           (Part IV · build-client-log)
│   │       ├── client.rs              # ModelClient trait         (Part IV · build-client-log)
│   │       ├── jsonl.rs               # append-only writer        (Part IV · build-client-log)
│   │       ├── anthropic.rs           # one provider impl         (Part IV · build-anthropic)
│   │       ├── dispatch.rs            # vignette×model×epoch loop (Part IV · build-dispatch)
│   │       └── main.rs                # `panoptes-run` binary     (Part IV · build-dispatch)
│   ├── panoptes-coding/               # STAGE 3 — coding I/O
│   │   ├── Cargo.toml                 #                           (Part V · build-sheets)
│   │   └── src/
│   │       ├── lib.rs                 #                           (Part V · build-sheets)
│   │       ├── sheets.rs              # blinded sheets + key      (Part V · build-sheets)
│   │       ├── validate.rs            # coded loader = validation (Part V · build-loader)
│   │       └── main.rs                # `panoptes-code` binary    (Part V · build-loader)
│   └── panoptes-cli/                  # the unified front door    (Part VII · build-cli)
│       ├── Cargo.toml
│       ├── src/main.rs                # `panoptes` subcommand enum
│       └── tests/pipeline.rs          # assert_cmd integration test
├── scenarios/
│   ├── families/ca_geo.toml           # content + metadata only   (Part III · build-family)
│   └── generated/                     # OUTPUT: manifest.csv + prompts/  (gitignore this)
├── harness/logs/                      # OUTPUT: responses.jsonl — append-only, sacred
├── coding/                            # OUTPUT: sheets/, coded/, blind_key.csv
├── reliability/README.md              # Stage-4 Python handoff    (Part VI · build-hardening)
└── README.md                          # run sequence + invariants (Part VI · build-hardening)

Build order matches the parts: core first (everything imports it), then gen → harness → coding in pipeline order, then the unified CLI on top.

The workspace manifest — every dependency, declared once

The root Cargo.toml you write in the very first build chapter declares all shared dependencies under [workspace.dependencies]. Later crate manifests then just write dep = { workspace = true } — so if a chapter seems to use a crate "out of nowhere" (strum, serde_with, …), it was declared here on day one:

[workspace]
resolver = "2"
members = [
    "crates/panoptes-core",
    "crates/panoptes-gen",
    "crates/panoptes-harness",
    "crates/panoptes-coding",
]

[workspace.dependencies]
serde = { version = "1", features = ["derive"] }   # derive Serialize/Deserialize (everywhere)
serde_json = "1"        # JSON + JSONL encoding (records, tests)
toml = "1"              # family-spec parsing (Part III)
serde_with = "3"        # NoneAsEmptyString for optional free-text (Part II codes)
strum = { version = "0.26", features = ["derive"] } # enum ↔ string Display/EnumString (Part II)
tera = "1"              # prompt templating (Part III)
reqwest = { version = "0.12", features = ["json"] } # HTTP client (Part IV)
tokio = { version = "1", features = ["full"] }      # async runtime (Part IV)
async-trait = "0.1"     # async fn in the ModelClient trait (Part IV)
sha2 = "0.10"           # prompt hashing (Part III) + opaque response ids (Part IV)
chrono = { version = "0.4", features = ["serde"] }  # run_at timestamps (Part II records)
itertools = "0.13"      # iproduct! cartesian grid (Part III)
clap = { version = "4", features = ["derive"] }     # every CLI binary
anyhow = "1"            # application-level errors
thiserror = "2"         # typed library errors (Part V loader)

(Add "crates/panoptes-cli" to members when you reach Part VII.)

Who depends on what

The two bold entries are corrections to the original task plan, which omitted them: dispatch.rs (Part IV) hashes response ids with sha2, and validate.rs (Part V) derives its error type with thiserror. Declare them when you create each crate's manifest and Parts IV–V will compile without surprises.

wiremock = "0.6", tempfile = "3", and assert_cmd are dev-dependencies declared per-crate (not in the workspace block).

Expected test progression

A quick reality check for the end of each part — if your counts differ, look for a missed test, not a missed feature: