Truth rules — file-backed policy

Phase 42 PRD: "truth/ dir at repo root — rule files, versioned in git."

This directory is the canonical home for TruthStore rules loaded from disk. Each *.toml file holds a set of TruthRule records for one task class. The truth crate's load_from_dir(path) walks this directory, parses every .toml file, and registers the rules it finds.

Structure

truth/
├── README.md                 ← this file
├── staffing.fill.toml        ← rules for task_class="staffing.fill"
└── staffing.any.toml         ← rules for task_class="staffing.any"

File naming is informational — load_from_dir respects whatever task_class the rule declares internally, NOT the filename. Using task-class-matching filenames is a convention for humans reading the git tree.

Rule shape

[[rule]]
id = "worker-active"
task_class = "staffing.fill"
description = "Worker must be active"
condition = { type = "FieldEquals", field = "worker.status", value = "active" }
action = { type = "Pass" }

condition.type is one of:

Always — always true
FieldEquals { field, value }
FieldMismatch { field, value }
FieldEmpty { field }
FieldGreater { field, threshold }
FieldContainsAny { field, needles }

action.type is one of:

Pass — rule informational; no enforcement
Reject { message } — short-circuit with error
Redact { fields } — mutate the context, strip fields
Block { message } — hard stop, alert

Composition

The crate's default_truth_store() continues to register rules in code for backward-compat. Operators can layer file-backed rules ON TOP via load_from_dir:

let store = truth::default_truth_store();
let store = truth::load_from_dir(&store, "/home/profit/lakehouse/truth")?;

File-loaded rules are additive — they do NOT replace in-code rules. This lets the staffing team tune rules at the file level (edit a threshold, add a new FieldContainsAny blocklist) without waiting for a code deploy.

Explicit non-goals

No hot reload — per Phase 42 PRD ("Truth reload is explicit in this phase"). Operators bounce the gateway or POST /v1/context refresh endpoint (future) to pick up changes.
No inheritance — each file stands alone; rule IDs must be unique across all files. Duplicate-ID detection is a load-time error.