Config-Driven Architecture — YAML Se Sab Control Karo

Configuration makes experiments reproducible only when it is validated and versioned. Unchecked YAML is untrusted input: a typo can change a threshold, a string can appear where a number was expected, and an unknown key can be silently ignored. Parse configuration into a strict schema, reject extras, and save the resolved configuration hash with every run.

Use YAML for research choices, not safety choices:

schema_version: 1
dataset:
  source: fixture_v3
  max_age_seconds: 900
  required_fields: [source_id, observed_at_utc, bid, ask]
research:
  hypothesis_id: baseline_spread_v1
  min_observations: 30
  abstain_on_missing: true
paper:
  starting_points: 1000
  max_points_per_event: 10
report:
  timezone: Asia/Karachi

Notice what is absent: endpoint methods, credentials, account identifiers, currency, and an execution mode. The program always runs paper-only. source selects a known fixture or a public GET adapter from a code-owned registry; it cannot be an arbitrary URL.

Validation rules should be precise. schema_version must equal a supported integer. Ages and counts have sensible positive bounds. Starting points and per-event limits are fictional integers, with no conversion to money. Unknown keys cause an error. Normalize the validated object to canonical JSON and calculate SHA-256; store that hash as config_hash in each event.

Layer configurations in an explicit order: packaged defaults, a named project file, and safe command-line overrides. Print the resolved non-secret configuration at startup. Never allow environment variables to bypass schema validation. A run is reproducible when the repository commit, fixture hashes, config hash, and parser version are all known.

Failure cases

max_age_seconds: "fast" must fail. max_points_per_event: -5 must fail. live_execution: true must fail as an unknown key. A duplicated YAML key should be rejected by the loader rather than accepting the last occurrence. A newer schema version should stop with an upgrade message, not be guessed.