weatherreporter/docs/policy/development.md

Development Policy

This document is the contributor workflow policy for weatherreporter. Developers and LLM coding agents should use it with docs/policy/architecture.md and docs/policy/documentation.md.

Repository Layout

• cmd/weatherreporter: binary entry point.
• internal/app: orchestration for generation, batches, fetch helpers, and inspection.
• internal/cli: command parsing, flag handling, help text, and JSON output.
• internal/config: configuration structs, defaults, loading, overrides, and validation.
• internal/fileutil: shared atomic filesystem write and copy helpers.
• internal/adapters/distributor: Distributor upload adapter.
• internal/adapters/weatherapi: Weather API HTTP adapter.
• internal/adapters/scriptorium: Scriptorium subprocess adapter.
• internal/weatherdata: normalized weather source facts, source metadata, and source warnings.
• internal/forecast: deterministic forecast derivation.
• internal/facts: collected and derived report fact contracts.
• internal/module: module IDs, config items, output envelopes, and snapshots.
• internal/report: report definitions, valid periods, batches, output names, and comparison declarations.
• internal/briefing: prompt-facing module value builders and module registry.
• internal/changes: structured Recent Changes comparison.
• internal/promptinput: Scriptorium data_package construction and validation.
• internal/state: filesystem paths, atomic JSON writes, metadata, lookup, and inspection support.
• internal/timeutil: clock, date, timezone, and period helpers.
• docs: user, operator, developer, integration, internal, policy, and roadmap documentation.
• examples: maintained copyable examples.

Local Validation

Use focused checks while editing and broader checks before committing:

go test ./...
go run ./cmd/weatherreporter --help
git diff --check

Useful focused checks:

go test ./internal/cli ./internal/config
go test ./internal/app ./internal/state
go test ./internal/adapters/distributor ./internal/adapters/weatherapi ./internal/adapters/scriptorium
go test ./internal/forecast ./internal/report ./internal/briefing ./internal/changes ./internal/promptinput

Run gofmt -w on changed Go files before committing.

Coding Conventions

• Keep domain logic out of cmd, internal/cli, and adapter packages.
• Prefer small explicit structs and functions over broad framework-style abstractions.
• Keep package APIs narrow and named around implemented behavior.
• Return errors with operation, path, endpoint, report, or RunID context.
• Do not log or expose secrets.
• Use context.Context for external calls, subprocesses, and orchestrated workflows that may be canceled.
• Use atomic writes for durable JSON artifacts where practical.
• Keep report selection and prompt IDs centralized in internal/report.
• Keep Scriptorium argv construction inside internal/adapters/scriptorium.
• Keep distributor package types and upload-client construction inside internal/adapters/distributor.
• Keep Weather API transport and envelope handling inside internal/adapters/weatherapi.

Dependency Policy

Prefer the Go standard library. Add dependencies only when they materially improve correctness, interoperability, security, or maintainability.

Current external dependencies:

• gitea.maximumdirect.net/eric/distributor for distributor source bundle construction and HTTP upload client behavior.
• gopkg.in/yaml.v3 for YAML configuration parsing.

When adding a dependency:

• explain why the standard library is not enough;
• keep dependency types from leaking across unrelated package boundaries;
• add tests for the behavior the dependency supports;
• update this policy if the dependency becomes part of contributor workflow.

Configuration Changes

Configuration is owned by internal/config.

When adding or changing a field:

• update Config and the nested config struct in config.go;
• add or adjust defaults in defaults.go when the field has a safe default;
• update loading or CLI override behavior in load.go only when needed;
• validate required values and accepted ranges in validate.go;
• add or update config tests;
• update docs/config.md and maintained examples when the field is user visible;
• keep secrets out of example config files.

Configuration precedence is:

1. CLI overrides supported by config.LoadOptions;
2. configuration file values;
3. built-in defaults.

The default config path is /usr/local/etc/weatherreporter/config.yml.

CLI Changes

The CLI is owned by internal/cli.

When adding or changing a command or flag:

• update help text and parser behavior together;
• convert parsed values into app-layer request structs;
• keep domain decisions in internal/app or domain packages;
• add parser or command tests in internal/cli;
• update docs/cli.md;
• update docs/operations.md or docs/troubleshooting.md when behavior affects operators.

CLI commands should return concise actionable errors and avoid printing partial JSON when command construction fails.

Components And Adapters

Use existing package boundaries before adding a package.

Add a new internal component only when it owns a distinct implemented contract. Define its inputs, outputs, state behavior, failure behavior, tests, and invariants in docs/internal/.

Adapters should stay thin:

• HTTP adapters own transport, request construction, envelope handling, and decode boundaries.
• subprocess adapters own argv construction, timeout handling, stdout/stderr capture, and exit-code interpretation.
• adapter packages should not own report selection, forecast summarization, Recent Changes, or prompt input schema decisions.

When an external contract changes, update the matching file under docs/integrations/.

Tests

Core tests must not require live Weather API, Scriptorium, or distributor services.

Preferred test patterns:

• fake command runners for subprocess behavior;
• httptest.Server for Weather API behavior;
• fake distributor upload clients for notification behavior;
• filesystem temp directories for state behavior;
• deterministic clocks for report periods and RunIDs;
• table tests for config validation, CLI parsing, period resolution, and threshold behavior.

Add focused tests near the package that owns the behavior. Use app-level tests for workflow ordering, persistence, and cross-package contracts.

Examples

Examples under examples/ must be real, maintained, and free of secrets.

When updating examples:

• use implemented config fields only;
• avoid private endpoints and credentials;
• keep comments short and operationally useful;
• add or update validation coverage when a new example file is introduced;
• link maintained examples from docs/config.md.

Do not add generated report examples unless they can be kept current without live external services.

Documentation Checklist

Documentation updates are part of behavior changes.

Update:

• README.md for project orientation or quickstart changes;
• docs/cli.md for command and flag changes;
• docs/config.md for config fields, defaults, and precedence changes;
• docs/operations.md for state, artifact, batch, inspection, and recovery behavior;
• docs/troubleshooting.md for recurring operator-facing failure modes;
• docs/internal/ for component contracts and invariants;
• docs/integrations/ for external Weather API, Scriptorium, or distributor contract changes;
• docs/roadmap/ only for unimplemented or deferred work.

Non-roadmap docs must describe implemented behavior only.