Policy Conditions Reference

Every policy rule has an "if" node that determines when the rule fires. This page documents the full condition syntax, operator catalog, and field vocabulary available in policy rules.

For rule actions and complete policy examples, see Policy Reference.

Condition structure

Four shapes are supported:

Nodes can be nested arbitrarily deep.

• {"all": []} is always true
• {"any": []} is always false

Operators

Keel supports 17 operators:

Plan tier availability

Custom policy authoring is gated by plan tier. The runtime engine evaluates all 17 operators on every project — the gate is on what callers may author in custom policies, not on what the engine supports.

Authoring violations are rejected at write time with the policy_authoring_level_exceeded error code. The error envelope identifies the offending rule index and the upgrade target.

Field vocabulary

Top-level fields

These fields are available in every policy evaluation:

Nested fields

Important limits:

• There is no dedicated resource.* namespace. Resource attributes must appear under attrs.* or context.*.
• There is no dedicated routing.* namespace.
• There is no array indexing syntax in field paths.
• context._keel.* fields are enriched by Keel opportunistically before evaluation. Caller-supplied _keel.* values are preserved and not overwritten. Each enrichment field fails independently — a missing value does not abort permit evaluation. Write policies using _keel fields with the expectation that a field may be absent.

Field availability by plan tier

Growth-plan custom policies (entitlement: policy_basic_authoring) may reference only a fixed whitelist of seven fields:

• context.model
• context.provider
• context.provider_meta.region
• context.provider_meta.data_retention
• context.estimated_cost_usd_micros
• context.prompt_token_count
• context.time_of_day

Business and Enterprise plans (entitlement: policy_full_authoring) may reference any field documented above, including all attrs.*, context.*, and context._keel.* paths. Field-vocabulary violations on the Growth grammar are rejected at write time with policy_authoring_level_exceeded.

Cross-field comparison

Leaf nodes can compare one field against another field by using a {"field": "..."} object as the value:

{
  "field": "token_estimate",
  "op": "gt",
  "value": {"field": "attrs.max_output_tokens_requested"}
}

If the referenced field does not resolve, the comparison evaluates to false.

Operator semantics

exists

exists checks whether the path resolves, not whether the resolved value is truthy.

• "value": true — the field must exist
• "value": false — the field must not exist

Non-boolean value literals fail closed.

Numeric operators (gt, gte, lt, lte)

Both operands must be numeric (int or float, not bool). Non-numeric operands fail closed.

contains

• On strings: substring containment
• On lists, tuples, or sets: element containment
• On other types: evaluates to false

starts_with / ends_with

Both operands must be strings. Comparison is case-sensitive.

matches_regex

matches_regex requires Business or higher (entitlement: policy_full_authoring).

Regex support is intentionally narrow to prevent denial-of-service risk in the policy evaluation path.

Write-time validation rejects:

• patterns longer than 500 characters
• backreferences
• lookaround assertions
• patterns that can trigger catastrophic backtracking

Runtime matching is capped at 5 ms and fails closed on timeout or error. A single policy document may contain at most 10 matches_regex conditions.

Prefer starts_with, ends_with, or contains when they are sufficient.

Length operators (len_gt, len_gte, len_lt, len_lte)

Applies to: strings, lists, tuples, sets, and dicts (by key count).

Missing fields, unsupported types, and negative or non-integer thresholds fail closed.

Resolution semantics

• Field paths are dot-path traversal over nested mappings
• Empty paths do not match
• Paths containing ".." do not match
• Missing intermediate keys do not match
• Missing fields fail closed for all comparison operators except exists

Examples

Deny outside business hours

{
  "any": [
    {"field": "context._keel.request_hour_utc", "op": "lt", "value": 9},
    {"field": "context._keel.request_hour_utc", "op": "gte", "value": 17}
  ]
}

Restrict by plan tier

{"field": "context._keel.project_plan", "op": "eq", "value": "starter"}

Match on request attributes

{
  "all": [
    {"field": "attrs.operation", "op": "eq", "value": "generate.text"},
    {"field": "model", "op": "ends_with", "value": "-mini"}
  ]
}

Check optional field presence before comparing

{
  "all": [
    {"field": "context.account_tier", "op": "exists", "value": true},
    {"field": "context.account_tier", "op": "eq", "value": "free"}
  ]
}

Compare one field to another

{
  "field": "token_estimate",
  "op": "gt",
  "value": {"field": "attrs.max_output_tokens_requested"}
}

Nested AND / OR

{
  "all": [
    {"field": "provider", "op": "eq", "value": "openai"},
    {
      "any": [
        {"field": "context._keel.country", "op": "eq", "value": "US"},
        {"field": "context._keel.country", "op": "eq", "value": "CA"}
      ]
    }
  ]
}

Related pages

• Policy Reference
• Decision Model
• Errors
• Plans & Entitlements