Motivation

CLI flags are tedious for repeated use. A config file enables consistent settings across invocations and easier deployment configuration.

Closes #10

Changes

• pkg/config/ — Config schema, file loading, validation, and ${VAR} / ${VAR:-default} environment variable interpolation
• cmd/config.go — distill config init (generate template) and distill config validate (check config file)
• cmd/api.go / cmd/serve.go — Viper bindings so config file values serve as fallbacks for CLI flags
• cmd/root.go — Updated config loading: searches for distill.yaml (not .distill), uses DISTILL_ env prefix with key replacer
• README.md — Config file documentation with example YAML

Config priority

CLI flags > environment variables > config file > defaults

Example

server:
  port: 8080
  host: 0.0.0.0

dedup:
  threshold: 0.15
  linkage: average
  lambda: 0.5

retriever:
  backend: pinecone
  index: my-index
  top_k: 50
  target_k: 8

auth:
  api_keys:
    - ${DISTILL_API_KEY}

Testing

• 15 unit tests covering: defaults, validation (port, threshold, lambda, backend, linkage), env interpolation, file loading, partial configs, invalid YAML, template generation
• CI will run go test ./... and golangci-lint