Settings Schema

The settings schema is the structural contract for UI/application preferences only. Runtime behavior belongs to profile/corp ledgers, not settings. Pydantic models in Python are the single source of truth for settings shape, JSON Schema is generated from them, and Python/Rust/TypeScript must parse settings identically.

Key files:

File	Role
src/capsem/builder/schema.py	Pydantic models (canonical schema)
config/settings/schema.generated.json	Generated JSON Schema
config/settings/ui-metadata.generated.json	Generated UI metadata and defaults from config/settings/settings.toml
crates/capsem-core/src/net/policy_config/types.rs	Rust settings serde contract
frontend/src/lib/types/settings.ts	TypeScript settings wire types
crates/capsem-core/tests/settings_spec.rs	Rust conformance tests
frontend/src/lib/__tests__/settings_spec.test.ts	TypeScript conformance tests
tests/test_settings_spec.py	Python schema + conformance tests
tests/settings_spec/golden.json	Golden fixture (shared by all three)

Two-Node-Type Design

The settings tree has exactly two node types, discriminated by the kind field:

graph TD
    ROOT["SettingsRoot"]
    ROOT --> G1["GroupNode\nkind=group"]
    ROOT --> G2["GroupNode\nkind=group"]
    G1 --> S1["SettingNode\nkind=setting\nsetting_type=bool"]
    G1 --> S2["SettingNode\nkind=setting\nsetting_type=text"]
    G1 --> S3["SettingNode\nkind=setting\nsetting_type=action"]
    G2 --> G3["GroupNode\nkind=group"]
    G3 --> S4["SettingNode\nkind=setting\nsetting_type=mcp_tool"]

GroupNode (kind="group"): container with children.

Field	Type	Required	Description
key	string	yes	Dot-separated path (e.g. ai.anthropic)
name	string	yes	Display name
description	string	no	Help text
enabled_by	string	no	Key of a bool setting that gates this group
enabled	bool	no	Effective enabled state (default true)
collapsed	bool	yes	Whether the UI renders this group collapsed
children	SettingsNode[]	yes	Nested groups and settings

SettingNode (kind="setting"): ordinary UI/application preferences and frontend actions. MCP runtime truth is profile-owned and is exposed by profile routes, not generated as settings leaves.

Field	Type	Required	Description
key	string	yes	Dot-separated path
name	string	yes	Display name
description	string	yes	Help text
setting_type	SettingType	yes	Data type (see enum table below)
default_value	any	no	Default from settings source
effective_value	any	no	Resolved value (corp > user > default)
source	PolicySource	no	Where effective value came from
modified	string	no	ISO timestamp of last user change
corp_locked	bool	no	Whether corp.toml overrides this
enabled_by	string	no	Key of a bool setting that gates this
enabled	bool	no	Effective enabled state
collapsed	bool	no	UI collapse state
metadata	SettingMetadata	no	Extra fields (defaults to empty)
history	HistoryEntry[]	no	Audit trail of value changes

Actions (check_update) use setting_type="action" with the relevant metadata fields. Consumers check setting_type, not kind.

SettingType Enum

13 values. The first 11 are data types with stored values. The last two are structural variants.

Value	Category	Description
text	value	Free-form string
number	value	Integer with optional min/max
url	value	URL string
email	value	Email address
apikey	value	API key (masked input, prefix hint)
bool	value	Boolean toggle
file	value	{ path, content } object
kv_map	value	{ key: value } dictionary
string_list	value	Array of strings
int_list	value	Array of integers
float_list	value	Array of floats
action	structural	UI button/widget, no stored value
mcp_tool	retired	Do not use for runtime MCP. MCP is profile-owned and route-backed.

Metadata Fields

All metadata lives in a single SettingMetadata object. Most fields are optional with sensible defaults. Fields are grouped by purpose.

Common fields

Field	Type	Default	Description
domains	string[]	[]	Domain patterns for network policy
choices	string[]	[]	Valid options (drives select widget)
min	int	null	Minimum value (number types)
max	int	null	Maximum value (number types)
rules	dict	{}	HTTP method permissions per rule
env_vars	string[]	[]	Environment variables injected into guest
collapsed	bool	false	Default collapse state
format	string	null	Value format hint (e.g. domain_list)
docs_url	string	null	Link to external documentation
prefix	string	null	Expected value prefix (e.g. sk-ant-)
filetype	string	null	File syntax type (e.g. json)
widget	Widget	null	Override default UI widget
side_effect	SideEffect	null	Frontend action on value change
hidden	bool	false	Exclude from UI, keep for policy
builtin	bool	false	Non-removable (system setting)
mask	bool	false	Mask display value
validator	string	null	Regex pattern for validation

Action-specific

Field	Type	Default	Description
action	ActionKind	null	Action identifier (check_update)

Retired MCP Metadata

MCP server and tool configuration is profile-owned. It is not authored through settings metadata and must be read through profile MCP routes.

Security Rule Schema

Security-event rules are loaded from corp.rules, profiles.rules, provider convenience blocks under ai.<provider>.rules, and referenced rule files:

[rule_files]
enforcement = "profiles/base/enforcement.toml"
sigma = "profiles/base/detection.yaml"

They are not ordinary settings leaves. The Rust loader validates the rule id, mandatory name, enum-backed action, optional detection_level, priority discipline, plugin requirements, and CEL fields against the first-party SecurityEvent roots.

Old callback-shaped fields such as on, if, decision, actions, and level are rejected by the rule parser. See Policy for the current TOML and Sigma rule formats.

JSON Schema Generation

The schema generation pipeline runs from Pydantic models to two output files:

flowchart LR
    PM["schema.py\nPydantic models"] --> MSJ["model_json_schema()"]
    MSJ --> SCH["config/settings/schema.generated.json"]
    GC["config/settings/settings.toml"] --> GD["generate_defaults_json()"]
    GD --> DEF["config/settings/ui-metadata.generated.json"]

just schema regenerates both files:

just schema
# Runs: uv run python scripts/generate_schema.py
# Outputs:
#   config/settings/schema.generated.json  (JSON Schema from Pydantic)
#   config/settings/ui-metadata.generated.json         (defaults from host settings source)

The JSON Schema is derived from SettingsRoot.model_json_schema(). It contains $defs for all model types (GroupNode, SettingNode, SettingMetadata, enums) and a properties.settings array at the root.

Cross-Language Conformance

A golden fixture at tests/settings_spec/golden.json is the contract. Three test suites parse the same fixture and verify identical structure:

flowchart TD
    GOLDEN["tests/settings_spec/golden.json\n(shared fixture)"]
    EXPECTED["tests/settings_spec/expected.json\n(expected counts + fields)"]

    GOLDEN --> PY["Python\ntests/test_settings_spec.py\n73 tests"]
    GOLDEN --> RS["Rust\ncrates/capsem-core/tests/settings_spec.rs\n12 tests"]
    GOLDEN --> TS["TypeScript\nfrontend/.../settings_spec.test.ts\n14 tests"]

    EXPECTED --> PY
    EXPECTED --> RS
    EXPECTED --> TS

    PY --> V["All three agree on:\n- total setting count\n- per-type counts\n- group count\n- setting fields\n- roundtrip serialization"]
    RS --> V
    TS --> V

99 tests total (73 Python, 12 Rust, 14 TypeScript). Every test suite checks:

Assertion	Verified by
Golden fixture parses	All three
Total setting count matches expected.json	All three
Per-type counts match expected.json	All three
Group count matches expected.json	All three
Setting key, name, type, enabled_by match	All three
Roundtrip serialize/deserialize	Python, Rust
All 13 setting types present	All three
Action settings have metadata.action	All three
File settings have { path, content }	All three
Hidden/builtin settings exist	All three
enabled_by references a valid bool	Python, TypeScript

Any schema change requires updating the golden fixture, expected.json, and all three test suites. just test runs all of them.

Data Flow

Two parallel paths connect the settings contract to the running application:

flowchart TD
    subgraph "Schema Path (dev time)"
        PM["schema.py\nPydantic models"] --> JSG["model_json_schema()"]
        JSG --> SCHEMA["config/settings/schema.generated.json"]
        SCHEMA --> TESTS["Conformance tests\n(Python + Rust + TypeScript)"]
    end

    subgraph "Data Path (build time)"
        TOML["config/settings/settings.toml\n(UI/app preferences only)"] --> GEN["generate_defaults_json()"]
        GEN --> DEF["config/settings/ui-metadata.generated.json"]
        DEF --> RUST["Rust include_str!()\nregistry.rs"]
        RUST --> BOOT["Settings route\nand UI defaults"]
    end

    subgraph "Golden Fixture Path (test time)"
        GOLDEN2["tests/settings_spec/golden.json"] --> PY2["Python tests"]
        GOLDEN2 --> RS2["Rust tests"]
        GOLDEN2 --> TS2["TypeScript tests"]
    end

The data path: host settings source is processed by generate_defaults_json() into config/settings/ui-metadata.generated.json. Rust embeds this file at compile time via include_str!() in registry.rs. Settings are UI/app preferences. Profiles own assets, rules, MCP, plugins, image payloads, and VM runtime posture.

The schema path: Pydantic models generate JSON Schema for documentation and validation. The conformance tests ensure all three languages agree on parsing.

Design Decision: Settings Nodes Only

The retired schema mixed settings and profile MCP runtime state:

Old type	Discriminant
Group	kind="group"
Leaf	kind="leaf"
Action	kind="action"
McpServer	kind="mcp_server"

The current settings schema keeps only settings-owned nodes:

Current type	Discriminant	Covers
Group	kind="group"	Containers with children
Leaf	kind="leaf"	Regular UI/application settings
Action	kind="action"	Settings-owned action controls

MCP server state is profile-owned and comes from /profiles/{profile_id}/mcp/..., not from the settings tree. Consumers must not invent a settings mcp_server node. Behavior is driven by setting_type and widget on settings leaves:

• Regular settings: setting_type in {text, number, bool, ...} — value fields populated
• Actions: setting_type="action" — metadata.action specifies the action kind Consumers match on kind (two arms: group vs. setting), then check setting_type when they need type-specific behavior. MCP servers and tools do not appear here; profile routes own MCP configuration and state.