wyrd-runtime 0.4.1

//! Runtime RBAC permission model.

use std::fmt;
use std::str::FromStr;

use serde::{Deserialize, Serialize};
pub use wyrd_spec::auth::{
    BifrostPermissionScope, BifrostSchemaScope, BifrostTableScope, GatewayAccess, PermissionScope,
    PermissionScopeError,
};
use wyrd_spec::card::agent::BuiltinTool;
use wyrd_spec::ids::CardUid;

/// One operation/object authorization triple.
///
/// Wyrd RBAC is `(resource, action, scope)`: the first two axes name the
/// operation and the third names the objects it reaches. Scope is required, so
/// a grant that targets no particular object states [`PermissionScope::All`]
/// explicitly rather than leaving the object axis unsaid.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(try_from = "PermissionWire")]
pub struct Permission {
    /// Resource the permission applies to.
    pub resource: Resource,
    /// Action allowed on the resource.
    pub action: Action,
    /// Objects of that resource the permission reaches.
    pub scope: PermissionScope,
}

/// Exact persisted and wire projection of one permission, before validation.
///
/// [`Permission`] deserializes through this shape so every decode — role JSON
/// in `wyrd.auth_roles.permissions`, a request body, a signed forwarding
/// envelope — runs the same validation. Scope has no default: a two-field
/// object is rejected rather than silently promoted to
/// [`PermissionScope::All`].
#[derive(Deserialize)]
#[serde(deny_unknown_fields)]
struct PermissionWire {
    /// Resource the permission applies to.
    resource: Resource,
    /// Action allowed on the resource.
    action: Action,
    /// Objects of that resource the permission reaches.
    scope: PermissionScope,
}

impl TryFrom<PermissionWire> for Permission {
    type Error = PermissionScopeError;

    /// Validates one decoded permission before it becomes an effective grant.
    ///
    /// # Errors
    ///
    /// Returns the scope's own identity failure, or
    /// [`PermissionScopeError::InvalidIdentifier`] with field `resource` when a
    /// Bifrost object scope is attached to a resource that owns no Bifrost
    /// object.
    fn try_from(wire: PermissionWire) -> Result<Self, Self::Error> {
        let permission = Self {
            resource: wire.resource,
            action: wire.action,
            scope: wire.scope,
        };
        permission.validate()?;
        Ok(permission)
    }
}

/// Resource the permission applies to.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum Resource {
    /// Cards and specs.
    Cards,
    /// Service cards and deployment-facing service operations.
    Services,
    /// Operator cards and invocations.
    Operators,
    /// Explicit invocation of a Verifier Card, optionally scoped to one UID.
    Verifier,
    /// Drift-backed Verifier Cards and drift observations.
    Drift,
    /// Artifact bytes and metadata.
    Artifacts,
    /// Audit records and audit cards.
    Audit,
    /// Policy cards and policy administration.
    Policy,
    /// Trigger cards.
    Triggers,
    /// Service and agent API-key principals.
    ServiceAccounts,
    /// Human user administration.
    Users,
    /// The tenant's human OIDC login connection: staging, testing,
    /// activating, deactivating, and removing the provider its people sign in
    /// through.
    ///
    /// Separate from [`Resource::ServiceAccounts`] so that holding credential
    /// administration alone never confers authority over who may sign in to
    /// the tenant. The built-in `admin` role reaches it through its wildcard;
    /// no other built-in role grants it.
    IdentityConnections,
    /// The tenant directory itself: creating, inspecting, suspending, and
    /// recovering administration for a tenant.
    ///
    /// This is a platform-control-plane resource. It governs the lifecycle of a
    /// tenant, never the resources inside one, so holding it grants no access
    /// to any tenant's data.
    Tenants,
    /// The deployment's platform-scope human identity: its one OIDC connection
    /// and the human platform principals registered against it.
    ///
    /// A platform-control-plane resource, distinct from [`Resource::Tenants`]
    /// so that administering who may sign in to the platform is visible in a
    /// grant and in audit separately from administering tenants. Holding it
    /// grants no access to any tenant's data.
    PlatformIdentity,
    /// Platform-scope credentials: the secrets that authenticate a platform
    /// principal to the control plane.
    ///
    /// Separate from [`Resource::PlatformIdentity`] because the two answer
    /// different questions. Identity administration decides *who* the platform
    /// recognizes; credential administration mints and retires the secrets that
    /// prove it. An operator may need to rotate the deployment's root
    /// credential without also being able to register new administrators.
    PlatformCredentials,
    /// Bifrost table definitions (DDL: create/list/describe).
    BifrostTable,
    /// Bifrost record ingest (the streaming write surface).
    BifrostRecord,
    /// Bifrost table reads (SQL/scan).
    BifrostQuery,
    /// Private Bifrost peer plane: reservation, execution, tail, and lifecycle.
    ///
    /// Role-neutral on purpose. Every peer-bearing target answers the same
    /// private services, so a Scribe and an Oracle are authorized by the same
    /// permission rather than by role-specific resources.
    BifrostPeer,
    /// Gateway administration (provider credentials, deployments, policies)
    /// and deployment/model invocation.
    Gateway,
    /// Captured gateway request and response payload fields.
    GatewayPayload,
    /// Built-in Agent tool invocation, optionally scoped to one tool.
    ///
    /// Invocation authority only: a tool's underlying Cards or Bifrost access
    /// is checked separately against those resources, and holding them never
    /// implies this one.
    Tool,
    /// One of several resources.
    AnyOf(Vec<Resource>),
    /// All resources.
    Wildcard,
}

/// Action performed against a resource.
#[derive(Clone, Debug, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum Action {
    /// Read.
    Read,
    /// Create or update.
    Write,
    /// Delete.
    Delete,
    /// Invoke runtime behavior.
    Invoke,
    /// Install or deploy.
    Install,
    /// Lock.
    Lock,
    /// Run.
    Run,
    /// Suspend a resource without destroying it, and resume it.
    Suspend,
    /// Restore administrative access a tenant can no longer reach itself.
    ///
    /// Named separately from [`Self::Write`] so the one operation that lets the
    /// platform plane act on a tenant's administration is distinguishable in a
    /// grant and in audit, rather than hiding inside a general write.
    Recover,
    /// One of several actions.
    AnyOf(Vec<Action>),
    /// All actions.
    Wildcard,
}

impl Resource {
    /// True if this resource covers `other`.
    #[must_use]
    pub fn covers(&self, other: &Resource) -> bool {
        match (self, other) {
            (Self::Wildcard, _) => true,
            (Self::AnyOf(resources), other) => {
                resources.iter().any(|resource| resource.covers(other))
            }
            (self_resource, other_resource) => self_resource == other_resource,
        }
    }

    /// The single resources this one names: an `AnyOf` flattened, anything
    /// else itself. Used to meet two grants member by member.
    fn members(&self) -> Vec<&Self> {
        match self {
            Self::AnyOf(resources) => resources.iter().flat_map(Self::members).collect(),
            resource => vec![resource],
        }
    }

    /// True when this resource owns Bifrost objects a grant may be scoped to.
    ///
    /// Bifrost query reads and record writes name a table. `AnyOf` and
    /// `Wildcard` are deliberately excluded: a multi-resource or wildcard grant
    /// reaches objects only through [`PermissionScope::All`].
    #[must_use]
    pub const fn accepts_bifrost_scope(&self) -> bool {
        matches!(self, Self::BifrostQuery | Self::BifrostRecord)
    }

    /// Stable label for this resource, or `None` for a composite `AnyOf`.
    ///
    /// Audit records the label rather than the enum's debug shape so a stored
    /// decision stays readable and comparable across releases.
    #[must_use]
    pub fn as_str(&self) -> Option<&'static str> {
        Some(match self {
            Self::Cards => "cards",
            Self::Services => "services",
            Self::Operators => "operators",
            Self::Verifier => "verifier",
            Self::Drift => "drift",
            Self::Artifacts => "artifacts",
            Self::Audit => "audit",
            Self::Policy => "policy",
            Self::Triggers => "triggers",
            Self::ServiceAccounts => "service_accounts",
            Self::Users => "users",
            Self::IdentityConnections => "identity_connections",
            Self::Tenants => "tenants",
            Self::PlatformIdentity => "platform_identity",
            Self::PlatformCredentials => "platform_credentials",
            Self::BifrostTable => "bifrost_table",
            Self::BifrostRecord => "bifrost_record",
            Self::BifrostQuery => "bifrost_query",
            Self::BifrostPeer => "bifrost_peer",
            Self::Gateway => "gateway",
            Self::GatewayPayload => "gateway_payload",
            Self::Tool => "tool",
            Self::Wildcard => "wildcard",
            Self::AnyOf(_) => return None,
        })
    }
}

impl Action {
    /// True if this action covers `other`.
    #[must_use]
    pub fn covers(&self, other: &Action) -> bool {
        match (self, other) {
            (Self::Wildcard, _) => true,
            (Self::AnyOf(actions), other) => actions.iter().any(|action| action.covers(other)),
            (self_action, other_action) => self_action == other_action,
        }
    }

    /// The single actions this one names: an `AnyOf` flattened, anything else
    /// itself. Used to meet two grants member by member.
    fn members(&self) -> Vec<&Self> {
        match self {
            Self::AnyOf(actions) => actions.iter().flat_map(Self::members).collect(),
            action => vec![action],
        }
    }

    /// Stable label for this action, or `None` for a composite `AnyOf`.
    ///
    /// Audit records the label rather than the enum's debug shape so a stored
    /// decision stays readable and comparable across releases.
    #[must_use]
    pub fn as_str(&self) -> Option<&'static str> {
        Some(match self {
            Self::Read => "read",
            Self::Write => "write",
            Self::Delete => "delete",
            Self::Invoke => "invoke",
            Self::Install => "install",
            Self::Lock => "lock",
            Self::Run => "run",
            Self::Suspend => "suspend",
            Self::Recover => "recover",
            Self::Wildcard => "wildcard",
            Self::AnyOf(_) => return None,
        })
    }
}

impl Permission {
    /// True if this permission covers `required`.
    #[must_use]
    pub fn covers(&self, required: &Permission) -> bool {
        self.resource.covers(&required.resource)
            && self.action.covers(&required.action)
            && self.scope.covers(&required.scope)
    }

    /// True when holding `self` makes `other` redundant in a [`PermissionSet`].
    ///
    /// Subsumption is [`Self::covers`] except that an `all`-scoped grant never
    /// subsumes an explicit gateway grant: `all` reaches only `open`
    /// deployments, while the explicit grant is the only one reaching a
    /// `granted` deployment. Requirement matching still uses `covers`.
    #[must_use]
    pub fn subsumes(&self, other: &Permission) -> bool {
        self.covers(other) && !(self.scope == PermissionScope::All && other.scope.is_gateway())
    }

    /// Rejects a permission whose object scope cannot apply to its operation.
    ///
    /// Bifrost object scope is meaningful only for Bifrost query reads and
    /// record writes, gateway object scope only for gateway invocation, and
    /// Verifier object scope only for `verifier:run`, and tool object scope only
    /// for `tool:invoke`. A wildcard or
    /// multi-resource grant on either axis keeps object-wide reach only with
    /// [`PermissionScope::All`], which is what stops a wildcard from inheriting
    /// one object's narrow authority.
    ///
    /// # Errors
    ///
    /// Returns the scope's own identity failure, or
    /// [`PermissionScopeError::InvalidIdentifier`] with field `resource` when an
    /// object scope is attached to a resource that does not own that object, or
    /// with field `action` when a Bifrost scope is attached to an action other
    /// than [`Action::Read`] for query or [`Action::Write`] for record, a
    /// gateway or tool scope to any action other than [`Action::Invoke`], or a
    /// Verifier scope to any action other than [`Action::Run`].
    pub fn validate(&self) -> Result<(), PermissionScopeError> {
        self.scope.validate()?;
        let (resource_accepts, required_action) = match &self.scope {
            PermissionScope::All => return Ok(()),
            PermissionScope::Bifrost(_) => (
                self.resource.accepts_bifrost_scope(),
                if self.resource == Resource::BifrostRecord {
                    Action::Write
                } else {
                    Action::Read
                },
            ),
            PermissionScope::Gateway(_) => (self.resource == Resource::Gateway, Action::Invoke),
            PermissionScope::Verifier(_) => (self.resource == Resource::Verifier, Action::Run),
            PermissionScope::Tool(_) => (self.resource == Resource::Tool, Action::Invoke),
        };
        if !resource_accepts {
            return Err(PermissionScopeError::InvalidIdentifier {
                field: "resource",
                value: self.resource.as_str().unwrap_or("any_of").to_owned(),
            });
        }
        if self.action != required_action {
            return Err(PermissionScopeError::InvalidIdentifier {
                field: "action",
                value: self.action.as_str().unwrap_or("any_of").to_owned(),
            });
        }
        Ok(())
    }

    /// Read cards.
    #[must_use]
    pub const fn card_read() -> Self {
        Self {
            resource: Resource::Cards,
            action: Action::Read,
            scope: PermissionScope::All,
        }
    }

    /// Write cards.
    #[must_use]
    pub const fn card_write() -> Self {
        Self {
            resource: Resource::Cards,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// Delete cards.
    #[must_use]
    pub const fn card_delete() -> Self {
        Self {
            resource: Resource::Cards,
            action: Action::Delete,
            scope: PermissionScope::All,
        }
    }

    /// Read artifacts.
    #[must_use]
    pub const fn artifact_read() -> Self {
        Self {
            resource: Resource::Artifacts,
            action: Action::Read,
            scope: PermissionScope::All,
        }
    }

    /// Write artifacts.
    #[must_use]
    pub const fn artifact_write() -> Self {
        Self {
            resource: Resource::Artifacts,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// Install services.
    #[must_use]
    pub const fn service_install() -> Self {
        Self {
            resource: Resource::Services,
            action: Action::Install,
            scope: PermissionScope::All,
        }
    }

    /// Write service accounts.
    #[must_use]
    pub const fn service_accounts_write() -> Self {
        Self {
            resource: Resource::ServiceAccounts,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// Administer the tenant's human OIDC login connection.
    #[must_use]
    pub const fn identity_connections_write() -> Self {
        Self {
            resource: Resource::IdentityConnections,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// Read the tenant's redacted Operator connections.
    #[must_use]
    pub const fn operators_read() -> Self {
        Self {
            resource: Resource::Operators,
            action: Action::Read,
            scope: PermissionScope::All,
        }
    }

    /// Create, update, rotate, and disable the tenant's Operator connections.
    #[must_use]
    pub const fn operators_write() -> Self {
        Self {
            resource: Resource::Operators,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// Invoke operators.
    #[must_use]
    pub const fn operator_invoke() -> Self {
        Self {
            resource: Resource::Operators,
            action: Action::Invoke,
            scope: PermissionScope::All,
        }
    }

    /// Invoke the one Verifier Card `verifier`, directly or as a manual run.
    ///
    /// The permission an explicit invocation requires: only a grant of this
    /// exact UID or [`Self::verifier_run_any`] covers it.
    #[must_use]
    pub const fn verifier_run(verifier: CardUid) -> Self {
        Self {
            resource: Resource::Verifier,
            action: Action::Run,
            scope: PermissionScope::Verifier(verifier),
        }
    }

    /// Invoke every Verifier Card in the tenant.
    ///
    /// The unscoped grant the built-in `workload` and `editor` Roles carry; a
    /// narrower custom Role grants [`Self::verifier_run`] for one UID.
    #[must_use]
    pub const fn verifier_run_any() -> Self {
        Self {
            resource: Resource::Verifier,
            action: Action::Run,
            scope: PermissionScope::All,
        }
    }

    /// Write triggers.
    #[must_use]
    pub const fn trigger_write() -> Self {
        Self {
            resource: Resource::Triggers,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// Read audit.
    #[must_use]
    pub const fn audit_read() -> Self {
        Self {
            resource: Resource::Audit,
            action: Action::Read,
            scope: PermissionScope::All,
        }
    }

    /// Lock policy.
    #[must_use]
    pub const fn policy_lock() -> Self {
        Self {
            resource: Resource::Policy,
            action: Action::Lock,
            scope: PermissionScope::All,
        }
    }

    /// Create a tenant on the platform control plane.
    #[must_use]
    pub const fn tenant_create() -> Self {
        Self {
            resource: Resource::Tenants,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// List tenants and inspect one tenant's lifecycle state.
    #[must_use]
    pub const fn tenant_read() -> Self {
        Self {
            resource: Resource::Tenants,
            action: Action::Read,
            scope: PermissionScope::All,
        }
    }

    /// Suspend and resume a tenant without destroying its state.
    #[must_use]
    pub const fn tenant_suspend() -> Self {
        Self {
            resource: Resource::Tenants,
            action: Action::Suspend,
            scope: PermissionScope::All,
        }
    }

    /// Restore administrative access to a tenant that has lost its own.
    ///
    /// The single named capability by which the platform plane reaches a
    /// tenant, kept distinct so it is visible in a grant and in audit rather
    /// than hidden inside a general write.
    #[must_use]
    pub const fn tenant_recover_admin() -> Self {
        Self {
            resource: Resource::Tenants,
            action: Action::Recover,
            scope: PermissionScope::All,
        }
    }

    /// Read the platform-scope identity configuration.
    ///
    /// Reading never yields provider secrets; the connection view is redacted
    /// at the boundary regardless of who holds this.
    #[must_use]
    pub const fn platform_identity_read() -> Self {
        Self {
            resource: Resource::PlatformIdentity,
            action: Action::Read,
            scope: PermissionScope::All,
        }
    }

    /// Configure the platform OIDC connection and register human platform
    /// principals.
    ///
    /// Deliberately the same permission for both: registering a principal
    /// against a connection you also control is one capability, and splitting
    /// it would suggest a separation the plane does not actually have.
    #[must_use]
    pub const fn platform_identity_write() -> Self {
        Self {
            resource: Resource::PlatformIdentity,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// List the non-secret metadata of a platform principal's credentials.
    ///
    /// Listing never yields credential material; it exists so an operator can
    /// see what is live, expired, or already retired before rotating.
    #[must_use]
    pub const fn platform_credential_read() -> Self {
        Self {
            resource: Resource::PlatformCredentials,
            action: Action::Read,
            scope: PermissionScope::All,
        }
    }

    /// Issue and revoke platform credentials.
    ///
    /// One permission for both halves of rotation: an operator who can mint a
    /// replacement must be able to retire what it replaces, and splitting them
    /// would leave a superseded credential live because the second half was
    /// separately granted.
    #[must_use]
    pub const fn platform_credential_write() -> Self {
        Self {
            resource: Resource::PlatformCredentials,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// Manage users.
    #[must_use]
    pub const fn users_manage() -> Self {
        Self {
            resource: Resource::Users,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// Write Bifrost records (the ingest surface).
    #[must_use]
    pub const fn bifrost_record_write() -> Self {
        Self {
            resource: Resource::BifrostRecord,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// Invoke the private Bifrost peer protocol.
    #[must_use]
    pub const fn bifrost_peer_invoke() -> Self {
        Self {
            resource: Resource::BifrostPeer,
            action: Action::Invoke,
            scope: PermissionScope::All,
        }
    }

    /// Read Bifrost table definitions.
    #[must_use]
    pub const fn bifrost_table_read() -> Self {
        Self {
            resource: Resource::BifrostTable,
            action: Action::Read,
            scope: PermissionScope::All,
        }
    }

    /// Write Bifrost table definitions (DDL).
    #[must_use]
    pub const fn bifrost_table_write() -> Self {
        Self {
            resource: Resource::BifrostTable,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// Install a `SystemShared` Bifrost table (cross-tenant DDL).
    #[must_use]
    pub const fn bifrost_table_install() -> Self {
        Self {
            resource: Resource::BifrostTable,
            action: Action::Install,
            scope: PermissionScope::All,
        }
    }

    /// Read Bifrost tables (SQL/scan).
    #[must_use]
    pub const fn bifrost_query_read() -> Self {
        Self {
            resource: Resource::BifrostQuery,
            action: Action::Read,
            scope: PermissionScope::All,
        }
    }

    /// Read gateway deployments, redacted credential metadata, and policies.
    #[must_use]
    pub const fn gateway_read() -> Self {
        Self {
            resource: Resource::Gateway,
            action: Action::Read,
            scope: PermissionScope::All,
        }
    }

    /// Create, replace, rotate, or revoke gateway configuration and policies.
    #[must_use]
    pub const fn gateway_write() -> Self {
        Self {
            resource: Resource::Gateway,
            action: Action::Write,
            scope: PermissionScope::All,
        }
    }

    /// Delete gateway credentials, deployments, and policies.
    #[must_use]
    pub const fn gateway_delete() -> Self {
        Self {
            resource: Resource::Gateway,
            action: Action::Delete,
            scope: PermissionScope::All,
        }
    }

    /// Invoke the gateway for the deployment or model named by `access`.
    #[must_use]
    pub const fn gateway_invoke(access: GatewayAccess) -> Self {
        Self {
            resource: Resource::Gateway,
            action: Action::Invoke,
            scope: PermissionScope::Gateway(access),
        }
    }

    /// Invoke the gateway for every `open` deployment and its models.
    ///
    /// The unscoped grant the built-in `workload` Role carries; a narrower
    /// custom Role uses [`Self::gateway_invoke`] with one deployment or model,
    /// which is also the only grant reaching a `granted` deployment.
    #[must_use]
    pub const fn gateway_invoke_any() -> Self {
        Self {
            resource: Resource::Gateway,
            action: Action::Invoke,
            scope: PermissionScope::All,
        }
    }

    /// Read captured gateway payload fields.
    #[must_use]
    pub const fn gateway_payload_read() -> Self {
        Self {
            resource: Resource::GatewayPayload,
            action: Action::Read,
            scope: PermissionScope::All,
        }
    }

    /// Invoke the one built-in Agent tool `tool`.
    ///
    /// The permission each tool call requires before it runs: only a grant of
    /// this exact tool, [`Self::tool_invoke_any`], or a covering wildcard
    /// covers it. It grants none of the tool's underlying data access.
    #[must_use]
    pub const fn tool_invoke(tool: BuiltinTool) -> Self {
        Self {
            resource: Resource::Tool,
            action: Action::Invoke,
            scope: PermissionScope::Tool(tool),
        }
    }

    /// Invoke every built-in Agent tool.
    #[must_use]
    pub const fn tool_invoke_any() -> Self {
        Self {
            resource: Resource::Tool,
            action: Action::Invoke,
            scope: PermissionScope::All,
        }
    }

    /// All permissions.
    #[must_use]
    pub const fn wildcard() -> Self {
        Self {
            resource: Resource::Wildcard,
            action: Action::Wildcard,
            scope: PermissionScope::All,
        }
    }
}

/// Renders the permission's *operation* as `resource:action`.
///
/// The object axis is deliberately absent: this string names which operation
/// was exercised for audit text and diagnostics, and is never the authorization
/// decision. Scoped authority travels as the typed [`Permission`] and, for
/// distributed execution, inside the scoped permission digest.
impl fmt::Display for Permission {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let resource = self.resource.as_str().ok_or(fmt::Error)?;
        let action = self.action.as_str().ok_or(fmt::Error)?;
        write!(f, "{resource}:{action}")
    }
}

/// Permission parse failure.
#[derive(Debug, thiserror::Error)]
#[error("permission must be formatted as resource:action")]
pub struct PermissionParseError;

/// Parses one `resource:action` operation token into an [`PermissionScope::All`]
/// permission.
///
/// The token language carries no object, so a parsed permission is the
/// object-wide form. Scoped grants are expressed only through the typed JSON
/// projection; there is no second string spelling for an object.
impl FromStr for Permission {
    type Err = PermissionParseError;

    fn from_str(value: &str) -> Result<Self, Self::Err> {
        let Some((resource, action)) = value.split_once(':') else {
            return Err(PermissionParseError);
        };
        Ok(Self {
            resource: parse_resource(resource)?,
            action: parse_action(action)?,
            scope: PermissionScope::All,
        })
    }
}

fn parse_resource(value: &str) -> Result<Resource, PermissionParseError> {
    Ok(match value {
        "cards" => Resource::Cards,
        "services" => Resource::Services,
        "operators" => Resource::Operators,
        "verifier" => Resource::Verifier,
        "drift" => Resource::Drift,
        "artifacts" => Resource::Artifacts,
        "audit" => Resource::Audit,
        "policy" => Resource::Policy,
        "triggers" => Resource::Triggers,
        "service_accounts" => Resource::ServiceAccounts,
        "users" => Resource::Users,
        "identity_connections" => Resource::IdentityConnections,
        "bifrost_table" => Resource::BifrostTable,
        "bifrost_record" => Resource::BifrostRecord,
        "bifrost_peer" => Resource::BifrostPeer,
        "bifrost_query" => Resource::BifrostQuery,
        "gateway" => Resource::Gateway,
        "gateway_payload" => Resource::GatewayPayload,
        "tool" => Resource::Tool,
        "wildcard" => Resource::Wildcard,
        _ => return Err(PermissionParseError),
    })
}

fn parse_action(value: &str) -> Result<Action, PermissionParseError> {
    Ok(match value {
        "read" => Action::Read,
        "write" => Action::Write,
        "delete" => Action::Delete,
        "invoke" => Action::Invoke,
        "install" => Action::Install,
        "lock" => Action::Lock,
        "run" => Action::Run,
        "wildcard" => Action::Wildcard,
        _ => return Err(PermissionParseError),
    })
}

/// Two permission sets whose exact shared authority no permission can state.
///
/// Delegation refuses on this rather than signing a token that widens either
/// party or drops authority both hold.
#[derive(Debug, thiserror::Error)]
#[error("shared authority for {permission} depends on deployment access and cannot be represented")]
pub struct UnrepresentableIntersection {
    /// The gateway grant one side holds only through `all`.
    pub permission: Permission,
}

/// Subsumption-aware permission collection.
#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
#[serde(transparent)]
pub struct PermissionSet(Vec<Permission>);

impl PermissionSet {
    /// Construct an empty set.
    #[must_use]
    pub fn new() -> Self {
        Self(Vec::new())
    }

    /// Insert one permission while keeping the set minimal.
    ///
    /// A grant is dropped only when another grant [`Permission::subsumes`] it,
    /// so an explicit gateway grant survives beside `all` in either order.
    pub fn insert(&mut self, permission: Permission) {
        if self.0.iter().any(|existing| existing.subsumes(&permission)) {
            return;
        }
        self.0.retain(|existing| !permission.subsumes(existing));
        self.0.push(permission);
    }

    /// True if the set covers `required`.
    #[must_use]
    pub fn contains(&self, required: &Permission) -> bool {
        self.0.iter().any(|permission| permission.covers(required))
    }

    /// True if a grant naming specific objects, not [`PermissionScope::All`],
    /// covers `required`.
    ///
    /// A `granted` gateway deployment admits only such a grant, so the
    /// unscoped invoke grant of the built-in Roles never reaches it.
    #[must_use]
    pub fn contains_object_scoped(&self, required: &Permission) -> bool {
        self.0.iter().any(|permission| {
            permission.scope != PermissionScope::All && permission.covers(required)
        })
    }

    /// True when the set grants `action` on `resource` under *any* object scope.
    ///
    /// This is coarse admission, not authorization: it answers "does this
    /// principal hold this capability at all", which is what a public route
    /// needs before it can resolve the objects a request actually touches. The
    /// authoritative decision is [`Self::contains`] against the resolved
    /// object, and no caller may substitute this for it.
    #[must_use]
    pub fn covers_operation(&self, resource: &Resource, action: &Action) -> bool {
        self.0.iter().any(|permission| {
            permission.resource.covers(resource) && permission.action.covers(action)
        })
    }

    /// The authority both sets grant: every permission covered by `self` and by
    /// `other`, and nothing else.
    ///
    /// Delegation mints with this so a delegated token can never carry more
    /// than its caller holds. Each pair of grants meets axis by axis through the
    /// same `covers` relations authorization uses: an `AnyOf` is split into its
    /// members, each axis keeps the narrower side when one covers the other, and
    /// a pair with a disjoint axis contributes nothing. A wildcard therefore
    /// yields the other grant, and a schema grant meeting a table grant in that
    /// schema yields the table grant.
    ///
    /// The one meet no scope can state is `all` against an explicit gateway
    /// grant: `all` reaches only `open` deployments, so their shared authority
    /// is "that deployment, only while it is open". Such a meet is accepted only
    /// when the rest of the result already covers it — both sides also hold
    /// `all`, or both grant the deployment explicitly; otherwise the complete
    /// intersection is unrepresentable.
    ///
    /// # Errors
    ///
    /// Returns [`UnrepresentableIntersection`] naming the first gateway grant
    /// whose shared authority depends on deployment access, so delegation can
    /// refuse instead of widening or silently dropping it.
    pub fn intersection(&self, other: &Self) -> Result<Self, UnrepresentableIntersection> {
        let mut meet = Self::new();
        let mut open_only = Vec::new();
        for left in &self.0 {
            for right in &other.0 {
                let Some(scope) = narrower(&left.scope, &right.scope, PermissionScope::covers)
                else {
                    continue;
                };
                let conditional = scope.is_gateway()
                    && (left.scope == PermissionScope::All || right.scope == PermissionScope::All);
                for resource in meets(
                    &left.resource.members(),
                    &right.resource.members(),
                    Resource::covers,
                ) {
                    for action in meets(
                        &left.action.members(),
                        &right.action.members(),
                        Action::covers,
                    ) {
                        let permission = Permission {
                            resource: resource.clone(),
                            action: action.clone(),
                            scope: scope.clone(),
                        };
                        if permission.validate().is_err() {
                            continue;
                        }
                        if conditional {
                            open_only.push(permission);
                        } else {
                            meet.insert(permission);
                        }
                    }
                }
            }
        }
        match open_only
            .into_iter()
            .find(|permission| !meet.contains(permission))
        {
            Some(permission) => Err(UnrepresentableIntersection { permission }),
            None => Ok(meet),
        }
    }

    /// Iterate over stored permissions.
    pub fn iter(&self) -> impl Iterator<Item = &Permission> {
        self.0.iter()
    }

    /// Number of stored permissions.
    #[must_use]
    pub fn len(&self) -> usize {
        self.0.len()
    }

    /// True when empty.
    #[must_use]
    pub fn is_empty(&self) -> bool {
        self.0.is_empty()
    }
}

/// The narrower of two values on one axis, or `None` when neither covers the
/// other and the axis is disjoint.
///
/// Exact for the resource, action, and scope axes because each is a tree under
/// its `covers` relation once `AnyOf` is split into members.
fn narrower<'a, T>(left: &'a T, right: &'a T, covers: fn(&T, &T) -> bool) -> Option<&'a T> {
    if covers(left, right) {
        Some(right)
    } else if covers(right, left) {
        Some(left)
    } else {
        None
    }
}

/// Every non-empty [`narrower`] meet between two lists of axis members.
fn meets<'a, T>(left: &[&'a T], right: &[&'a T], covers: fn(&T, &T) -> bool) -> Vec<&'a T> {
    left.iter()
        .flat_map(|l| right.iter().filter_map(move |r| narrower(*l, *r, covers)))
        .collect()
}

impl FromIterator<Permission> for PermissionSet {
    fn from_iter<T: IntoIterator<Item = Permission>>(iter: T) -> Self {
        let mut set = Self::new();
        for permission in iter {
            set.insert(permission);
        }
        set
    }
}

#[cfg(test)]
mod tests {
    use super::{Action, Permission, PermissionScope, PermissionSet, Resource};
    use serde_json::json;
    use wyrd_spec::auth::{BifrostPermissionScope, BifrostSchemaScope, BifrostTableScope};

    #[test]
    fn serde_round_trip_every_variant() {
        let resources = [
            Resource::Cards,
            Resource::Services,
            Resource::Operators,
            Resource::Verifier,
            Resource::Drift,
            Resource::Artifacts,
            Resource::Audit,
            Resource::Policy,
            Resource::Triggers,
            Resource::ServiceAccounts,
            Resource::Users,
            Resource::IdentityConnections,
            Resource::AnyOf(vec![Resource::Operators, Resource::Triggers]),
            Resource::Wildcard,
        ];
        for resource in resources {
            let value = serde_json::to_value(&resource).expect("resource serializes");
            let round_trip: Resource =
                serde_json::from_value(value).expect("resource deserializes");
            assert_eq!(round_trip, resource);
        }

        let actions = [
            Action::Read,
            Action::Write,
            Action::Delete,
            Action::Invoke,
            Action::Install,
            Action::Lock,
            Action::Run,
            Action::AnyOf(vec![Action::Read, Action::Write]),
            Action::Wildcard,
        ];
        for action in actions {
            let value = serde_json::to_value(&action).expect("action serializes");
            let round_trip: Action = serde_json::from_value(value).expect("action deserializes");
            assert_eq!(round_trip, action);
        }
    }

    #[test]
    fn bifrost_permissions_round_trip_through_wire_strings() {
        for (permission, wire) in [
            (Permission::bifrost_record_write(), "bifrost_record:write"),
            (Permission::bifrost_table_read(), "bifrost_table:read"),
            (Permission::bifrost_table_write(), "bifrost_table:write"),
            (Permission::bifrost_query_read(), "bifrost_query:read"),
            (Permission::bifrost_peer_invoke(), "bifrost_peer:invoke"),
        ] {
            assert_eq!(permission.to_string(), wire);
            assert_eq!(wire.parse::<Permission>().expect("wire parses"), permission);
            let json = serde_json::to_value(&permission).expect("serializes");
            assert_eq!(
                serde_json::from_value::<Permission>(json).expect("deserializes"),
                permission
            );
        }
    }

    #[test]
    fn bifrost_record_write_is_distinct_from_table_write() {
        assert!(!Permission::bifrost_table_write().covers(&Permission::bifrost_record_write()));
        assert!(!Permission::bifrost_record_write().covers(&Permission::bifrost_table_write()));
        assert!(Permission::wildcard().covers(&Permission::bifrost_record_write()));
    }

    #[test]
    fn covers_wildcard_resource() {
        let permission = Permission {
            resource: Resource::Wildcard,
            action: Action::Read,
            scope: PermissionScope::All,
        };

        assert!(permission.covers(&Permission::card_read()));
        assert!(!permission.covers(&Permission::card_write()));
    }

    #[test]
    fn covers_wildcard_action() {
        let permission = Permission {
            resource: Resource::Cards,
            action: Action::Wildcard,
            scope: PermissionScope::All,
        };

        assert!(permission.covers(&Permission::card_read()));
        assert!(permission.covers(&Permission::card_write()));
        assert!(!permission.covers(&Permission::artifact_write()));
    }

    /// The resource-and-action wildcard covers every concrete grant, including
    /// Bifrost record writes outside the Card family.
    ///
    /// # Panics
    /// Panics when the wildcard fails to cover any probed permission.
    #[test]
    fn covers_double_wildcard() {
        let permission = Permission::wildcard();

        assert!(permission.covers(&Permission::card_read()));
        assert!(permission.covers(&Permission::card_write()));
        assert!(permission.covers(&Permission::bifrost_record_write()));
    }

    #[test]
    fn covers_anyof_resource() {
        let permission = Permission {
            resource: Resource::AnyOf(vec![Resource::Operators, Resource::Triggers]),
            action: Action::Invoke,
            scope: PermissionScope::All,
        };

        assert!(permission.covers(&Permission::operator_invoke()));
        assert!(permission.covers(&Permission {
            resource: Resource::Triggers,
            action: Action::Invoke,
            scope: PermissionScope::All,
        }));
        assert!(!permission.covers(&Permission {
            resource: Resource::Cards,
            action: Action::Invoke,
            scope: PermissionScope::All,
        }));
    }

    #[test]
    fn permission_set_subsumption_drops_redundant() {
        let mut set = PermissionSet::from_iter([Permission::card_read()]);
        set.insert(Permission::wildcard());

        assert_eq!(set.len(), 1);
        assert_eq!(set.iter().next(), Some(&Permission::wildcard()));
    }

    #[test]
    fn permission_set_subsumption_skips_covered() {
        let mut set = PermissionSet::from_iter([Permission::wildcard()]);
        set.insert(Permission::card_read());

        assert_eq!(set.len(), 1);
        assert_eq!(set.iter().next(), Some(&Permission::wildcard()));
    }

    /// Set membership resolves through coverage, so a set holding only the
    /// wildcard contains every concrete permission.
    ///
    /// # Panics
    /// Panics when the wildcard-only set does not contain a probed permission.
    #[test]
    fn permission_set_contains_resolves_through_wildcard() {
        let set = PermissionSet::from_iter([Permission::wildcard()]);

        assert!(set.contains(&Permission::card_read()));
        assert!(set.contains(&Permission::bifrost_record_write()));
    }

    #[test]
    fn permission_set_jsonb_round_trip() {
        let permissions = vec![
            Permission::card_write(),
            Permission::card_read(),
            Permission {
                resource: Resource::AnyOf(vec![Resource::Operators, Resource::Triggers]),
                action: Action::Invoke,
                scope: PermissionScope::All,
            },
            Permission::wildcard(),
        ];
        let value = serde_json::to_value(&permissions).expect("permissions serialize");

        assert_eq!(
            value,
            json!([
                {"resource": "cards", "action": "write", "scope": "all"},
                {"resource": "cards", "action": "read", "scope": "all"},
                {"resource": {"any_of": ["operators", "triggers"]}, "action": "invoke", "scope": "all"},
                {"resource": "wildcard", "action": "wildcard", "scope": "all"}
            ])
        );

        let round_trip: Vec<Permission> =
            serde_json::from_value(value).expect("permissions deserialize");
        assert_eq!(round_trip, permissions);
    }

    /// Proves gateway grants round-trip their approved wire names, a
    /// deployment invoke grant covers that deployment's models only, only an
    /// object-scoped grant counts as scoped, and a gateway object scope is
    /// refused anywhere but gateway invoke.
    ///
    /// # Panics
    /// Panics when a fixture fails to build or an assertion fails.
    #[test]
    fn gateway_permissions_are_typed_and_scope_checked() {
        use super::GatewayAccess;
        use wyrd_spec::ids::{ModelId, ProviderDeploymentName};
        let openai = ProviderDeploymentName::new("openai").expect("valid deployment");
        let provider = GatewayAccess::Deployment {
            deployment: openai.clone(),
        };
        let model = |name: &str| GatewayAccess::Model {
            deployment: openai.clone(),
            model: ModelId::new(name).expect("valid model"),
        };
        let required = Permission::gateway_invoke(model("gpt-4o"));
        assert!(PermissionSet::from_iter([Permission::gateway_invoke_any()]).contains(&required));
        assert!(
            !PermissionSet::from_iter([Permission::gateway_invoke_any()])
                .contains_object_scoped(&required),
            "the unscoped grant is not a grant of the deployment"
        );
        assert!(
            PermissionSet::from_iter([Permission::gateway_invoke(provider.clone())])
                .contains_object_scoped(&required)
        );

        assert_eq!(
            Permission::gateway_payload_read().to_string(),
            "gateway_payload:read"
        );
        assert_eq!(
            "gateway:write".parse::<Permission>().expect("parses"),
            Permission::gateway_write()
        );
        assert!(
            Permission::gateway_invoke(provider.clone())
                .covers(&Permission::gateway_invoke(model("gpt-4o")))
        );
        assert!(
            !Permission::gateway_invoke(model("gpt-4o"))
                .covers(&Permission::gateway_invoke(model("gpt-4.1")))
        );
        assert!(
            !Permission::gateway_invoke(provider.clone()).covers(&Permission::gateway_read()),
            "invoke never grants admin metadata reads"
        );
        assert_eq!(
            serde_json::to_value(Permission::gateway_invoke(model("gpt-4o"))).expect("serializes"),
            json!({
                "resource": "gateway",
                "action": "invoke",
                "scope": {"gateway": {"model": {"deployment": "openai", "model": "gpt-4o"}}}
            })
        );
        for (resource, action) in [("gateway", "read"), ("cards", "invoke")] {
            assert!(
                serde_json::from_value::<Permission>(json!({
                    "resource": resource,
                    "action": action,
                    "scope": {"gateway": {"deployment": {"deployment": "openai"}}}
                }))
                .is_err(),
                "{resource}:{action}"
            );
        }
    }

    /// Proves `verifier:run` parses, covers only its exact Verifier UID or the
    /// unscoped grant, and refuses a Verifier scope on any other operation.
    #[test]
    fn verifier_run_is_uid_scoped() {
        use wyrd_spec::ids::CardUid;
        let uid = |value: &str| CardUid::new(value).expect("valid uuid7");
        let bound = uid("01927b4c-0000-7000-8000-000000000001");
        let other = uid("01927b4c-0000-7000-8000-000000000002");

        assert_eq!(
            "verifier:run".parse::<Permission>().expect("parses"),
            Permission::verifier_run_any()
        );
        assert!(Permission::verifier_run_any().covers(&Permission::verifier_run(bound.clone())));
        assert!(
            Permission::verifier_run(bound.clone())
                .covers(&Permission::verifier_run(bound.clone()))
        );
        assert!(
            !Permission::verifier_run(other).covers(&Permission::verifier_run(bound.clone())),
            "an unrelated UID grant does not cover"
        );
        assert_eq!(
            serde_json::to_value(Permission::verifier_run(bound.clone())).expect("serializes"),
            json!({"resource": "verifier", "action": "run", "scope": {"verifier": bound.as_str()}})
        );
        for (resource, action) in [("verifier", "read"), ("cards", "run")] {
            assert!(
                serde_json::from_value::<Permission>(json!({
                    "resource": resource,
                    "action": action,
                    "scope": {"verifier": bound.as_str()}
                }))
                .is_err(),
                "{resource}:{action}"
            );
        }
    }

    /// Proves `tool:invoke` decodes in both approved wire forms, refuses
    /// non-built-in names and misplaced tool scopes, covers and intersects by
    /// exact name, and is neither implied by domain grants nor implies them.
    ///
    /// # Panics
    /// Panics when a tool grant decodes, covers, or intersects incorrectly.
    #[test]
    fn tool_invoke_is_exact_name_scoped_and_independent() {
        use wyrd_spec::card::agent::BuiltinTool;
        let query = Permission::tool_invoke(BuiltinTool::BifrostQuery);
        let read = Permission::tool_invoke(BuiltinTool::FsRead);
        let global = Permission::tool_invoke_any();

        let decode = |value: serde_json::Value| serde_json::from_value::<Permission>(value);
        let global_json = json!({"resource": "tool", "action": "invoke", "scope": "all"});
        let exact_json =
            json!({"resource": "tool", "action": "invoke", "scope": {"tool": "bifrost.query"}});
        assert_eq!(decode(global_json.clone()).expect("global"), global);
        assert_eq!(decode(exact_json.clone()).expect("exact"), query);
        assert_eq!(
            serde_json::to_value(&global).expect("serialize"),
            global_json
        );
        assert_eq!(serde_json::to_value(&query).expect("serialize"), exact_json);
        assert_eq!("tool:invoke".parse::<Permission>().expect("parses"), global);
        for tool in BuiltinTool::ALL {
            let value =
                json!({"resource": "tool", "action": "invoke", "scope": {"tool": tool.as_str()}});
            assert_eq!(
                decode(value).expect("built-in"),
                Permission::tool_invoke(tool)
            );
        }
        for name in [
            "bifrost",
            "bifrost.*",
            "fs.read/etc",
            "/usr/bin/python",
            "FS.READ",
            "http.fetch",
        ] {
            let value = json!({"resource": "tool", "action": "invoke", "scope": {"tool": name}});
            assert!(decode(value).is_err(), "{name}");
        }
        for (resource, action) in [
            ("tool", "read"),
            ("tool", "run"),
            ("cards", "invoke"),
            ("bifrost_query", "read"),
            ("wildcard", "invoke"),
        ] {
            let value =
                json!({"resource": resource, "action": action, "scope": {"tool": "fs.read"}});
            assert!(decode(value).is_err(), "{resource}:{action}");
        }

        assert!(global.covers(&query));
        assert!(query.covers(&query));
        assert!(!query.covers(&read));
        assert!(!query.covers(&global));
        assert!(Permission::wildcard().covers(&query));
        for domain in [
            Permission::card_read(),
            Permission::bifrost_query_read(),
            Permission::verifier_run_any(),
        ] {
            assert!(!domain.covers(&query), "{domain}");
            assert!(!global.covers(&domain), "{domain}");
        }

        let set = |grants: &[Permission]| grants.iter().cloned().collect::<PermissionSet>();
        let meet = |left: &[Permission], right: &[Permission]| {
            set(left).intersection(&set(right)).expect("representable")
        };
        assert!(meet(std::slice::from_ref(&query), std::slice::from_ref(&read)).is_empty());
        for (left, right) in [(&global, &query), (&query, &global)] {
            let shared = meet(std::slice::from_ref(left), std::slice::from_ref(right));
            assert_eq!(shared.iter().collect::<Vec<_>>(), vec![&query]);
        }
        let attenuated = meet(&[Permission::wildcard()], std::slice::from_ref(&query));
        assert!(attenuated.contains(&query) && !attenuated.contains(&read));

        let role: Vec<Permission> =
            serde_json::from_value(json!([global_json, exact_json, {"resource": "bifrost_query", "action": "read", "scope": "all"}]))
                .expect("role permissions decode");
        let role = role.into_iter().collect::<PermissionSet>();
        assert!(role.contains(&query) && role.contains(&read));
    }

    /// Proves an explicit gateway grant survives merging beside `all` in either
    /// order and under wildcard or `AnyOf` axes, and that delegation meets
    /// gateway grants exactly: `all` with `all` stays `all`, explicit grants
    /// meet to the narrower grant, a mixed pair whose explicit result the other
    /// side also holds explicitly is representable, and `all` meeting an
    /// explicit grant alone — "that deployment, only if open" — is refused in
    /// both directions instead of minting the explicit grant.
    ///
    /// # Panics
    /// Panics when a merge drops an explicit grant, a representable meet
    /// differs from the exact shared authority, or an unrepresentable meet
    /// succeeds.
    #[test]
    fn gateway_grants_survive_merge_and_intersect_exactly() {
        use super::GatewayAccess;
        use wyrd_spec::ids::{ModelId, ProviderDeploymentName};
        let restricted = ProviderDeploymentName::new("restricted").expect("valid deployment");
        let deployment = Permission::gateway_invoke(GatewayAccess::Deployment {
            deployment: restricted.clone(),
        });
        let model = Permission::gateway_invoke(GatewayAccess::Model {
            deployment: restricted,
            model: ModelId::new("gpt-4o").expect("valid model"),
        });
        let any_resource_invoke = Permission {
            resource: Resource::AnyOf(vec![Resource::Gateway, Resource::Cards]),
            action: Action::Wildcard,
            scope: PermissionScope::All,
        };
        for broad in [
            Permission::gateway_invoke_any(),
            Permission::wildcard(),
            any_resource_invoke,
        ] {
            for set in [
                PermissionSet::from_iter([broad.clone(), deployment.clone()]),
                PermissionSet::from_iter([deployment.clone(), broad.clone()]),
            ] {
                assert!(set.contains_object_scoped(&model), "{broad} kept explicit");
                assert!(set.contains(&Permission::gateway_invoke_any()));
            }
        }

        let all = PermissionSet::from_iter([Permission::gateway_invoke_any()]);
        let explicit = PermissionSet::from_iter([deployment.clone()]);
        let narrow = PermissionSet::from_iter([model.clone()]);
        assert_eq!(all.intersection(&all).expect("representable"), all);
        assert_eq!(
            explicit.intersection(&narrow).expect("representable"),
            narrow
        );
        assert!(all.intersection(&explicit).is_err());
        assert!(explicit.intersection(&all).is_err());
        let wildcard = PermissionSet::from_iter([Permission::wildcard()]);
        assert!(wildcard.intersection(&narrow).is_err());

        let mixed = PermissionSet::from_iter([Permission::gateway_invoke_any(), deployment]);
        assert_eq!(mixed.intersection(&narrow).expect("representable"), narrow);
        assert_eq!(narrow.intersection(&mixed).expect("representable"), narrow);
        assert_eq!(
            mixed.intersection(&all).expect("representable"),
            all,
            "both hold all; only one holds the explicit grant"
        );
        assert!(
            PermissionSet::from_iter([Permission::card_read()])
                .intersection(&explicit)
                .expect("no overlap is the representable empty result")
                .is_empty()
        );
    }

    /// Builds the schema-scoped Bifrost query-read grant the journey seeds.
    fn logs_schema_grant() -> Permission {
        Permission {
            resource: Resource::BifrostQuery,
            action: Action::Read,
            scope: PermissionScope::Bifrost(BifrostPermissionScope::Schema(BifrostSchemaScope {
                catalog: "bifrost".to_owned(),
                schema: "logs".to_owned(),
            })),
        }
    }

    /// Builds the exact table-scoped Bifrost query-read requirement for one UID.
    fn table_requirement(schema: &str, uid: uuid::Uuid) -> Permission {
        Permission {
            resource: Resource::BifrostQuery,
            action: Action::Read,
            scope: PermissionScope::Bifrost(BifrostPermissionScope::Table(BifrostTableScope {
                catalog: "bifrost".to_owned(),
                schema: schema.to_owned(),
                table_uid: uid,
            })),
        }
    }

    /// Proves the intersection keeps only authority both sides grant, at the
    /// narrower scope: wildcard, schema, exact-object, and disjoint grants.
    ///
    /// # Panics
    /// Panics when an intersection keeps broader, one-sided, or disjoint
    /// authority, or drops authority both sides grant.
    #[test]
    fn intersection_keeps_only_the_narrower_shared_authority() {
        let uid = uuid::Uuid::from_u128(0x77);
        let set = |permissions: Vec<Permission>| permissions.into_iter().collect::<PermissionSet>();

        let wildcard = set(vec![Permission::wildcard()]);
        let target = set(vec![Permission::card_read(), logs_schema_grant()]);
        assert_eq!(
            wildcard.intersection(&target).expect("representable"),
            target
        );
        assert_eq!(
            target.intersection(&wildcard).expect("representable"),
            target
        );

        let schema = set(vec![logs_schema_grant()]);
        let table = set(vec![table_requirement("logs", uid)]);
        assert_eq!(schema.intersection(&table).expect("representable"), table);
        assert_eq!(table.intersection(&schema).expect("representable"), table);

        let other_table = set(vec![table_requirement("logs", uuid::Uuid::from_u128(0x78))]);
        assert!(
            table
                .intersection(&other_table)
                .expect("representable")
                .is_empty()
        );
        assert!(
            set(vec![table_requirement("traces", uid)])
                .intersection(&schema)
                .expect("representable")
                .is_empty()
        );

        let all_reads = set(vec![Permission {
            resource: Resource::Wildcard,
            action: Action::Read,
            scope: PermissionScope::All,
        }]);
        let cards_any = set(vec![Permission {
            resource: Resource::AnyOf(vec![Resource::Cards, Resource::Audit]),
            action: Action::Wildcard,
            scope: PermissionScope::All,
        }]);
        assert_eq!(
            all_reads.intersection(&cards_any).expect("representable"),
            set(vec![Permission::card_read(), Permission::audit_read()])
        );

        assert!(
            set(vec![Permission::card_write()])
                .intersection(&set(vec![
                    Permission::card_read(),
                    Permission::bifrost_record_write()
                ]))
                .expect("representable")
                .is_empty()
        );
    }

    /// Proves the persisted permission JSON is exactly the approved three-field
    /// projection for `all`, schema, and table scope, in both directions.
    ///
    /// # Panics
    /// Panics when a permission fails to serialize or deserialize, or its
    /// JSON or decoded value differs from the approved projection.
    #[test]
    fn scoped_permission_json_matches_the_approved_projection() {
        let uid = uuid::Uuid::from_u128(0x99);
        let cases = [
            (
                Permission::bifrost_query_read(),
                json!({"resource": "bifrost_query", "action": "read", "scope": "all"}),
            ),
            (
                logs_schema_grant(),
                json!({
                    "resource": "bifrost_query",
                    "action": "read",
                    "scope": {"bifrost": {"schema": {"catalog": "bifrost", "schema": "logs"}}}
                }),
            ),
            (
                table_requirement("traces", uid),
                json!({
                    "resource": "bifrost_query",
                    "action": "read",
                    "scope": {"bifrost": {"table": {
                        "catalog": "bifrost",
                        "schema": "traces",
                        "table_uid": uid.to_string(),
                    }}}
                }),
            ),
        ];

        for (permission, wire) in cases {
            assert_eq!(
                serde_json::to_value(&permission).expect("permission serializes"),
                wire
            );
            assert_eq!(
                serde_json::from_value::<Permission>(wire).expect("permission deserializes"),
                permission
            );
        }
    }

    /// Proves Bifrost object scope applies to record writes as well as query
    /// reads, a table-scoped write covers only its own table, and the scope is
    /// still refused on any other resource or action pairing.
    ///
    /// # Panics
    /// Panics when the table-scoped record write fails validation or its
    /// round trip, covers another table or the unscoped requirement, is not
    /// covered by the unscoped write, or validates on record read, query
    /// write, or table write.
    #[test]
    fn bifrost_scope_applies_to_record_write_and_query_read_only() {
        let calls = uuid::Uuid::from_u128(0xca11);
        let spans = uuid::Uuid::from_u128(0x5a45);
        let table_write = |uid| Permission {
            resource: Resource::BifrostRecord,
            action: Action::Write,
            scope: PermissionScope::Bifrost(BifrostPermissionScope::Table(BifrostTableScope {
                catalog: "bifrost".to_owned(),
                schema: "gateway".to_owned(),
                table_uid: uid,
            })),
        };
        table_write(calls)
            .validate()
            .expect("scoped record write is valid");
        assert!(table_write(calls).covers(&table_write(calls)));
        assert!(!table_write(calls).covers(&table_write(spans)));
        assert!(
            !table_write(calls).covers(&Permission::bifrost_record_write()),
            "a table-scoped write never covers the unscoped requirement"
        );
        assert!(Permission::bifrost_record_write().covers(&table_write(spans)));
        let wire = serde_json::to_value(table_write(calls)).expect("serializes");
        assert_eq!(
            serde_json::from_value::<Permission>(wire).expect("round-trips"),
            table_write(calls)
        );
        for (resource, action) in [
            (Resource::BifrostRecord, Action::Read),
            (Resource::BifrostQuery, Action::Write),
            (Resource::BifrostTable, Action::Write),
        ] {
            let permission = Permission {
                resource,
                action,
                ..table_write(calls)
            };
            assert!(permission.validate().is_err(), "{permission}");
        }
    }

    /// Proves `scope` is mandatory: the pre-scope two-field form is rejected
    /// rather than defaulted, so no compatibility decoder exists.
    #[test]
    fn scope_is_required_and_has_no_compatibility_decoder() {
        let error = serde_json::from_value::<Permission>(json!({
            "resource": "bifrost_query",
            "action": "read"
        }))
        .expect_err("the unscoped two-field form is not accepted");

        assert!(error.to_string().contains("scope"), "{error}");
    }

    /// Proves a Bifrost object scope only attaches to a resource that owns a
    /// Bifrost object; `cards` and `wildcard` both fail closed at decode.
    ///
    /// # Panics
    /// Panics when a schema scope decodes on `cards` or `wildcard`, or the
    /// decode error does not name the resource.
    #[test]
    fn bifrost_scope_is_rejected_on_an_unrelated_resource() {
        for resource in ["cards", "wildcard"] {
            let error = serde_json::from_value::<Permission>(json!({
                "resource": resource,
                "action": "read",
                "scope": {"bifrost": {"schema": {"catalog": "bifrost", "schema": "logs"}}}
            }))
            .expect_err("a Bifrost object scope needs a Bifrost object resource");

            assert!(error.to_string().contains("resource"), "{error}");
        }
    }

    /// Proves Bifrost object scope is valid only for the exact `read` action.
    ///
    /// Without this, persisted or signed JSON could carry a Bifrost scope on
    /// `wildcard`, which then covers the required read and turns corrupt role
    /// JSON into effective read authority instead of a decode failure.
    ///
    /// # Panics
    /// Panics when a schema scope decodes on `write`, `wildcard`, or an
    /// `any_of` action, a refusal does not name the action, or the exact
    /// query read is refused.
    #[test]
    fn bifrost_scope_is_rejected_on_a_non_read_action() {
        for action in [
            json!("write"),
            json!("wildcard"),
            json!({"any_of": ["read", "write"]}),
        ] {
            let error = serde_json::from_value::<Permission>(json!({
                "resource": "bifrost_query",
                "action": action,
                "scope": {"bifrost": {"schema": {"catalog": "bifrost", "schema": "logs"}}}
            }))
            .expect_err("a Bifrost object scope only applies to an exact read");

            assert!(error.to_string().contains("action"), "{error}");
        }

        serde_json::from_value::<Permission>(json!({
            "resource": "bifrost_query",
            "action": "read",
            "scope": {"bifrost": {"schema": {"catalog": "bifrost", "schema": "logs"}}}
        }))
        .expect("exact query read stays valid for Bifrost scope");
    }

    /// Proves a structurally valid but empty object identity is not an object:
    /// malformed identities fail at decode, never at check time.
    ///
    /// # Panics
    /// Panics when a schema scope with an empty schema segment decodes.
    #[test]
    fn malformed_scope_identity_is_rejected_at_decode() {
        assert!(
            serde_json::from_value::<Permission>(json!({
                "resource": "bifrost_query",
                "action": "read",
                "scope": {"bifrost": {"schema": {"catalog": "bifrost", "schema": ""}}}
            }))
            .is_err(),
            "an empty schema segment is not an object identity"
        );
    }

    /// Proves coverage requires resource, action, and scope together, and that
    /// wildcard authority stays object-wide only because its scope is `All`.
    #[test]
    fn coverage_is_three_axis() {
        let logs = uuid::Uuid::from_u128(1);
        let traces = uuid::Uuid::from_u128(2);

        // Schema scope reaches current and future tables in that exact schema.
        assert!(logs_schema_grant().covers(&table_requirement("logs", logs)));
        assert!(logs_schema_grant().covers(&table_requirement("logs", traces)));
        assert!(!logs_schema_grant().covers(&table_requirement("traces", traces)));

        // Exact table scope reaches only its own UID.
        let exact = table_requirement("traces", traces);
        assert!(exact.covers(&table_requirement("traces", traces)));
        assert!(!exact.covers(&table_requirement("traces", logs)));

        // `All` reaches every object, but only for its own resource and action.
        assert!(Permission::bifrost_query_read().covers(&table_requirement("logs", logs)));
        assert!(!Permission::bifrost_table_read().covers(&table_requirement("logs", logs)));

        // A wildcard grant is object-wide only because its scope is `All`.
        assert!(Permission::wildcard().covers(&table_requirement("logs", logs)));

        // A scoped grant never satisfies an object-wide requirement.
        assert!(!logs_schema_grant().covers(&Permission::bifrost_query_read()));
    }

    /// Proves coarse operation admission and authoritative object coverage are
    /// distinct: a scoped grant admits the operation but authorizes only its object.
    #[test]
    fn covers_operation_admits_a_scoped_grant_without_authorizing_an_object() {
        let set = PermissionSet::from_iter([logs_schema_grant()]);

        assert!(set.covers_operation(&Resource::BifrostQuery, &Action::Read));
        assert!(!set.covers_operation(&Resource::BifrostTable, &Action::Read));
        assert!(!set.contains(&Permission::bifrost_query_read()));
        assert!(set.contains(&table_requirement("logs", uuid::Uuid::from_u128(7))));
        assert!(!set.contains(&table_requirement("traces", uuid::Uuid::from_u128(7))));
    }

    /// Proves set subsumption runs on all three axes: disjoint scopes are both
    /// retained, and an `All`-scoped grant absorbs every narrower scope.
    #[test]
    fn permission_set_keeps_scopes_that_do_not_subsume_each_other() {
        let mut set = PermissionSet::from_iter([logs_schema_grant()]);
        set.insert(table_requirement("traces", uuid::Uuid::from_u128(3)));

        assert_eq!(set.len(), 2);

        set.insert(Permission::bifrost_query_read());

        assert_eq!(set.len(), 1);
        assert_eq!(set.iter().next(), Some(&Permission::bifrost_query_read()));
    }

    #[test]
    fn permission_wire_token_roundtrips() {
        let parsed = "cards:write"
            .parse::<Permission>()
            .expect("permission parses");

        assert_eq!(parsed, Permission::card_write());
        assert_eq!(parsed.to_string(), "cards:write");
    }

    /// Proves the retired `evals` resource is an ordinary unknown resource in
    /// every wire form — string grants, structured grants and `any_of`
    /// members, for `run` and `invoke` — while `verifier:run` and unrelated
    /// grants keep parsing and covering exactly as before.
    ///
    /// # Panics
    /// Panics when a retired form parses or a retained grant stops parsing or
    /// covering.
    #[test]
    fn retired_permission_is_unknown() {
        for action in ["run", "invoke"] {
            assert!(
                format!("evals:{action}").parse::<Permission>().is_err(),
                "evals:{action}"
            );
            assert!(
                serde_json::from_value::<Permission>(
                    json!({"resource": "evals", "action": action, "scope": "all"})
                )
                .is_err(),
                "structured evals:{action}"
            );
            assert!(
                serde_json::from_value::<Permission>(json!({
                    "resource": {"any_of": ["operators", "evals"]},
                    "action": action,
                    "scope": "all"
                }))
                .is_err(),
                "any_of evals:{action}"
            );
        }
        let verifier = "verifier:run"
            .parse::<Permission>()
            .expect("verifier:run parses");
        assert_eq!(verifier, Permission::verifier_run_any());
        assert!(verifier.covers(&Permission::verifier_run(
            wyrd_spec::ids::CardUid::new("01927b4c-0000-7000-8000-000000000001").expect("uid")
        )));
        assert_eq!(
            "operators:invoke"
                .parse::<Permission>()
                .expect("unrelated grant parses"),
            Permission::operator_invoke()
        );
    }
}