act-runtime 0.13.1

//! The audit record types. These are field carriers: `emit.rs` is the only
//! module that turns them into `tracing` events.

use std::fmt;
use std::time::Duration;

use sha2::{Digest, Sha256};

/// Frozen attribute names. Every emitted field uses one of these constants.
///
/// These are a public contract — the OTLP exporter maps them straight onto
/// span/event attributes, so renaming one invalidates existing dashboards.
/// OpenTelemetry semantic conventions are used where one exists; everything
/// else lives under the `act.*` namespace.
pub mod attr {
    pub const COMPONENT_REF: &str = "act.component.ref";
    pub const COMPONENT_DIGEST: &str = "act.component.digest";
    pub const TOOL_NAME: &str = "act.tool.name";
    pub const TOOL_ARGS_SHA256: &str = "act.tool.args_sha256";
    /// Full tool-argument values, only present when `--audit-args` is set.
    /// `TOOL_ARGS_SHA256` above is still emitted alongside it — this field
    /// widens the envelope, it never replaces the digest. Session args are
    /// never carried by either field: `ToolCallStart` has no such member.
    pub const TOOL_ARGS: &str = "act.tool.args";
    pub const SESSION_ID: &str = "act.session.id";
    // Caller and call identity. Key names come from ACT-CONSTANTS.md §5,
    // which already reserves std:agent-id / std:request-id / std:traceparent
    // / std:tracestate — this host is the first reader of any of them.
    pub const AGENT_ID: &str = "act.agent.id";
    pub const REQUEST_ID: &str = "act.request.id";
    pub const TRACE_PARENT: &str = "act.trace.parent";
    pub const TRACE_STATE: &str = "act.trace.state";
    pub const TRANSPORT: &str = "act.transport";
    pub const OUTCOME: &str = "act.outcome";
    pub const DURATION_MS: &str = "act.duration_ms";
    pub const CAPABILITY_ID: &str = "act.capability.id";
    pub const RESOURCE_KEY: &str = "act.resource.key";
    pub const RESOURCE_ACTION: &str = "act.resource.action";
    pub const DECISION: &str = "act.decision";
    pub const POLICY_MODE: &str = "act.policy.mode";
    pub const POLICY_ACTOR: &str = "act.policy.actor";
    pub const POLICY_REASON: &str = "act.policy.reason";
    pub const POLICY_RULE: &str = "act.policy.rule";
    /// Whether the component declared this capability class in `act.toml`.
    pub const CAPABILITY_DECLARED: &str = "act.capability.declared";
    /// Whether this decision must never fold into the per-call rollup, even
    /// when it resolves to `Allow`. Set for `act:consent` decisions — see
    /// `CapDecisionRecord::never_rollup`.
    pub const NEVER_ROLLUP: &str = "act.decision.never_rollup";
    /// The `kind` string of a credential that was handed to a component —
    /// `std:fields` for everything this host writes, since a credential is a
    /// set of named fields and nothing else (design §3.2). Recorded because it
    /// is a required member of the published WIT `secret` record and a store
    /// may hold one written elsewhere. Non-secret by construction: it names a
    /// shape, never a value.
    pub const CREDENTIAL_KIND: &str = "act.credential.kind";
    /// Whether this run has any channel that can answer an interactive `ask`
    /// prompt at all (a real TTY, or an MCP client offering elicitation) —
    /// as opposed to headless / ACT-HTTP, where every `ask` decision
    /// degrades to deny before a human is ever involved. A per-run fact,
    /// repeated on every `act.ceiling_class` event so the layer never has to
    /// infer it from anything but typed fields.
    pub const CONSENT_PROMPT_CHANNEL: &str = "act.consent.prompt_channel";
}

/// Which transport dispatched the call.
///
/// `#[non_exhaustive]`: hosts embedding this crate serve over transports the
/// CLI has no name for, and adding one for them must not be a breaking change.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
#[non_exhaustive]
pub enum Transport {
    #[default]
    Cli,
    Mcp,
}

impl fmt::Display for Transport {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(match self {
            Transport::Cli => "cli",
            Transport::Mcp => "mcp",
        })
    }
}

/// How the tool call ended.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Outcome {
    Ok,
    /// The component returned a `tool-event::error` or an `err` result.
    ToolError,
    /// The host failed to run the call at all.
    HostError,
    /// Not yet wired up: the host drops the stream handle and wasmtime
    /// unwinds on cancellation, but that path doesn't record this outcome
    /// yet. Kept — with its `Display` arm and the assertion below — to
    /// record the intent for when it is.
    #[allow(dead_code)]
    Cancelled,
}

impl fmt::Display for Outcome {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(match self {
            Outcome::Ok => "ok",
            Outcome::ToolError => "tool-error",
            Outcome::HostError => "host-error",
            Outcome::Cancelled => "cancelled",
        })
    }
}

/// The resolved verdict. Widens `act_policy::Decision`: the classifier is
/// three-valued, but `Ask` settles into an allow or a deny once the operator
/// (or the degrade-to-deny rule) answers.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Decision4 {
    Allow,
    Deny,
    AskAllow,
    AskDeny,
}

impl Decision4 {
    /// True when this record must print the moment it resolves rather than
    /// being folded into the per-call rollup.
    pub fn is_exception(&self) -> bool {
        !matches!(self, Decision4::Allow)
    }
}

impl fmt::Display for Decision4 {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(match self {
            Decision4::Allow => "allow",
            Decision4::Deny => "deny",
            Decision4::AskAllow => "ask-allow",
            Decision4::AskDeny => "ask-deny",
        })
    }
}

/// Who decided.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Actor {
    /// Resolved from the static ceiling × grant intersection.
    Static,
    /// A human answered an `ask` prompt.
    User,
    /// An external policy engine decided (toolserver tier; unused in the CLI).
    Policy,
}

impl fmt::Display for Actor {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(match self {
            Actor::Static => "static",
            Actor::User => "user",
            Actor::Policy => "policy",
        })
    }
}

/// The fields known when a tool call begins. Outcome and duration are
/// recorded onto the span when it finishes.
#[derive(Debug, Clone)]
pub struct ToolCallStart {
    pub component_ref: String,
    pub digest: String,
    pub tool: String,
    pub args_sha256: String,
    /// Full arguments rendered as JSON, present only when `--audit-args` is
    /// set. `None` by default, in which case only `args_sha256` is emitted —
    /// this is the field that keeps the default path a digest, never values.
    pub args_json: Option<String>,
    pub session_id: Option<String>,
    pub transport: Transport,
    /// `std:agent-id` — informational caller identity, never a principal.
    pub agent_id: Option<String>,
    /// `std:request-id`, or a host-generated id. Always present, so an
    /// operator can always join one audit line to one client log line.
    pub request_id: String,
    /// `std:traceparent` (W3C Trace Context) as received.
    pub traceparent: Option<String>,
    /// `std:tracestate` as received.
    pub tracestate: Option<String>,
}

/// One capability decision, emitted as an event inside the tool-call span.
#[derive(Debug, Clone)]
pub struct CapDecisionRecord {
    pub cap_id: String,
    pub key: String,
    pub action: String,
    pub decision: Decision4,
    pub mode: String,
    pub actor: Actor,
    pub reason: Option<String>,
    /// The ceiling rule that matched, when the provider can attribute one.
    /// Drives rollup grouping (Task 2).
    pub rule: Option<String>,
    /// True for a decision on a *semantic* class (`act:consent`), which must
    /// never fold into the per-call rollup even when it resolves to `Allow`.
    ///
    /// A physical class's rollup is right for what it is: nobody wants a
    /// line per filesystem `read`. A semantic class is the opposite — there
    /// are few of them, each is a distinct, consequential act (`DROP
    /// DATABASE analytics`), and *which subject* is the whole content of the
    /// decision. Rolling one into `db:drop: 1 request` throws away the one
    /// fact the line exists to carry, the same way folding a credential
    /// issue into a count would (see `render_credential_issue`'s doc, which
    /// states the identical rule for that record).
    ///
    /// An explicit flag, not `action == "request"`: `consent::gate::ACTION`
    /// is a private constant, and string-matching it across the module
    /// boundary between `consent::gate` and `audit::layer` is fragile —
    /// renaming or repurposing the action string would silently start
    /// folding consent decisions again with no test failing until someone
    /// noticed the missing audit line.
    ///
    /// `false` for every physical-class decision (fs/http/sockets/
    /// credentials); `true` only where `consent::gate::ConsentGate::decide`
    /// sets it before emitting.
    pub never_rollup: bool,
}

impl CapDecisionRecord {
    /// A statically-resolved decision (ceiling x grant, no human involved).
    /// Shared by every capability class so the record shape cannot drift
    /// between providers.
    pub fn statik(
        cap_id: &str,
        key: &str,
        action: &str,
        decision: Decision4,
        mode: &str,
        rule: Option<String>,
    ) -> Self {
        Self::statik_with_reason(cap_id, key, action, decision, mode, rule, None)
    }

    /// `statik`, but lets the caller override the default `Deny` reason
    /// ("outside ceiling"). Some decision points deny for a reason other
    /// than "the operation didn't match the ceiling" — a redirect hop
    /// leaving the allowed host, a DNS-resolved address landing in a
    /// deny-CIDR — and an operator reading "outside ceiling" for both would
    /// not be able to tell them apart from an ordinary allow/deny-list
    /// mismatch. `None` reproduces `statik`'s default exactly. Still the
    /// same shared shape and still no per-class builder: any capability
    /// class can call this, not just HTTP.
    pub fn statik_with_reason(
        cap_id: &str,
        key: &str,
        action: &str,
        decision: Decision4,
        mode: &str,
        rule: Option<String>,
        reason: Option<&str>,
    ) -> Self {
        Self {
            cap_id: cap_id.to_string(),
            key: key.to_string(),
            action: action.to_string(),
            decision,
            mode: mode.to_string(),
            actor: Actor::Static,
            // Only a Deny carries a reason at all — same invariant `statik`
            // enforces. A custom `reason` on a non-Deny call is dropped
            // rather than surfaced, so an Allow record can never render as
            // if something had been refused.
            reason: (decision == Decision4::Deny)
                .then(|| reason.map_or_else(|| "outside ceiling".to_string(), str::to_string)),
            rule,
            never_rollup: false,
        }
    }

    /// An `ask` that has resolved — either a human actually answered it, or
    /// there was no channel to ask on at all and it degraded to deny (§5).
    ///
    /// `has_channel` is what tells the two apart, and it changes both `actor`
    /// and `reason`: a real human refusal is `actor: User, reason: "denied
    /// by user"`, but a no-channel degrade never consulted anyone, so
    /// recording it identically would make the trail lie about who decided.
    /// `DenyPrompter` (the only prompter with `has_channel() == false`)
    /// always resolves `allowed = false`, so `has_channel: false` in
    /// practice always pairs with `allowed: false` — but the reason is
    /// driven by `has_channel` alone, not inferred from `allowed`, so the
    /// record stays correct even if that pairing ever changes.
    pub fn answered(cap_id: &str, key: &str, allowed: bool, has_channel: bool) -> Self {
        let (actor, reason) = if has_channel {
            (
                Actor::User,
                if allowed {
                    "allowed by user"
                } else {
                    "denied by user"
                },
            )
        } else {
            // Nobody was consulted — resolved the same way a statically
            // ceiling-denied request is, so it is attributed the same way.
            (Actor::Static, "no prompt channel")
        };
        Self {
            cap_id: cap_id.to_string(),
            key: key.to_string(),
            action: String::new(),
            decision: if allowed {
                Decision4::AskAllow
            } else {
                Decision4::AskDeny
            },
            mode: "ask".to_string(),
            actor,
            reason: Some(reason.to_string()),
            rule: None,
            never_rollup: false,
        }
    }
}

/// One capability class as resolved at instantiation.
#[derive(Debug, Clone)]
pub struct CeilingClassRecord {
    pub cap_id: String,
    pub mode: String,
    /// Whether the component declared this class in `act.toml`.
    pub declared: bool,
    /// Whether this run has an interactive prompt channel at all. `mode ==
    /// "ask"` alone does not mean an `ask` will ever reach a human: headless
    /// / ACT-HTTP has no channel, so every `ask` decision degrades to deny
    /// before anyone is asked. Same value on every class in one
    /// instantiation — it describes the run, not the capability — but
    /// carried per-record so the layer never needs anything but this event's
    /// own typed fields to decide whether to warn.
    pub has_prompt_channel: bool,
}

/// One credential handed over to a component.
///
/// Deliberately **not** a `CapDecisionRecord`. That one records what policy
/// decided; this one records that material actually crossed into the guest —
/// design §9 requires an entry for "every `get-secret` that returns material:
/// component, session, key, timestamp — never values", and the two answer
/// different questions when read back.
///
/// `component_ref` and `session_id` are carried on the record itself rather
/// than inherited from an enclosing span: an audit record must identify what
/// it describes from its own fields, not from whatever happens to enclose the
/// call site. That keeps the record intact wherever the host later chooses to
/// serve a credential from, and keeps the layer's decoding a function of the
/// event alone.
///
/// There is no field that could hold a value, and none is added: the type is
/// the enforcement. `list-secrets` has no record of its own on purpose —
/// design §9 again, "it would bury the one event that matters".
#[derive(Debug, Clone)]
pub struct CredentialIssueRecord {
    pub component_ref: String,
    /// The session the credential was issued under. Never empty in practice:
    /// `get-secret` requires a session (design §3.3).
    pub session_id: String,
    /// The store lookup key, as the guest asked for it — untrusted input, so
    /// every renderer escapes it.
    pub key: String,
    pub kind: String,
}

/// Lowercase hex SHA-256, no `sha256:` prefix.
pub fn sha256_hex(data: &[u8]) -> String {
    let mut hasher = Sha256::new();
    hasher.update(data);
    hasher
        .finalize()
        .iter()
        .map(|b| format!("{b:02x}"))
        .collect()
}

/// Milliseconds, saturating — used for the `act.duration_ms` field.
pub fn duration_ms(d: Duration) -> u64 {
    u64::try_from(d.as_millis()).unwrap_or(u64::MAX)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn attribute_names_are_frozen() {
        // These strings are a public contract: the OTLP exporter and any
        // dashboard built on it key off them. Changing one is a breaking change.
        assert_eq!(attr::COMPONENT_REF, "act.component.ref");
        assert_eq!(attr::COMPONENT_DIGEST, "act.component.digest");
        assert_eq!(attr::TOOL_NAME, "act.tool.name");
        assert_eq!(attr::TOOL_ARGS_SHA256, "act.tool.args_sha256");
        assert_eq!(attr::TOOL_ARGS, "act.tool.args");
        assert_eq!(attr::SESSION_ID, "act.session.id");
        assert_eq!(attr::AGENT_ID, "act.agent.id");
        assert_eq!(attr::REQUEST_ID, "act.request.id");
        assert_eq!(attr::TRACE_PARENT, "act.trace.parent");
        assert_eq!(attr::TRACE_STATE, "act.trace.state");
        assert_eq!(attr::TRANSPORT, "act.transport");
        assert_eq!(attr::OUTCOME, "act.outcome");
        assert_eq!(attr::DURATION_MS, "act.duration_ms");
        assert_eq!(attr::CAPABILITY_ID, "act.capability.id");
        assert_eq!(attr::RESOURCE_KEY, "act.resource.key");
        assert_eq!(attr::RESOURCE_ACTION, "act.resource.action");
        assert_eq!(attr::DECISION, "act.decision");
        assert_eq!(attr::POLICY_MODE, "act.policy.mode");
        assert_eq!(attr::POLICY_ACTOR, "act.policy.actor");
        assert_eq!(attr::POLICY_REASON, "act.policy.reason");
        assert_eq!(attr::POLICY_RULE, "act.policy.rule");
        assert_eq!(attr::CAPABILITY_DECLARED, "act.capability.declared");
        assert_eq!(attr::CONSENT_PROMPT_CHANNEL, "act.consent.prompt_channel");
    }

    #[test]
    fn static_records_carry_a_reason_only_when_denied() {
        let a = CapDecisionRecord::statik(
            "wasi:filesystem",
            "/data/x",
            "read",
            Decision4::Allow,
            "allowlist",
            Some("/data/**".into()),
        );
        assert!(a.reason.is_none());
        assert_eq!(a.actor, Actor::Static);

        let d =
            CapDecisionRecord::statik("wasi:http", "evil:443", "GET", Decision4::Deny, "ask", None);
        assert_eq!(d.reason.as_deref(), Some("outside ceiling"));
    }

    #[test]
    fn statik_with_reason_overrides_the_default_deny_reason() {
        let r = CapDecisionRecord::statik_with_reason(
            "wasi:http",
            "blocked.example:443",
            "",
            Decision4::Deny,
            "allowlist",
            None,
            Some("redirect target outside ceiling"),
        );
        assert_eq!(r.reason.as_deref(), Some("redirect target outside ceiling"));
    }

    #[test]
    fn statik_with_reason_none_falls_back_to_statiks_default() {
        let with_none = CapDecisionRecord::statik_with_reason(
            "wasi:http",
            "k",
            "",
            Decision4::Deny,
            "allowlist",
            None,
            None,
        );
        assert_eq!(with_none.reason.as_deref(), Some("outside ceiling"));

        // An Allow is still never given a reason, even if the caller passes
        // one — only Deny carries a reason at all, same invariant `statik`
        // already enforces.
        let allow_with_reason = CapDecisionRecord::statik_with_reason(
            "wasi:http",
            "k",
            "",
            Decision4::Allow,
            "allowlist",
            None,
            Some("should be dropped"),
        );
        assert!(allow_with_reason.reason.is_none());
    }

    #[test]
    fn answered_records_are_attributed_to_the_user() {
        let r = CapDecisionRecord::answered("wasi:filesystem", "/k", false, true);
        assert_eq!(r.decision, Decision4::AskDeny);
        assert_eq!(r.actor, Actor::User);
        assert_eq!(r.reason.as_deref(), Some("denied by user"));
        assert_eq!(
            CapDecisionRecord::answered("wasi:filesystem", "/k", true, true).decision,
            Decision4::AskAllow
        );
    }

    #[test]
    fn a_no_channel_degrade_is_not_attributed_to_the_user() {
        // M1: `DenyPrompter` resolves every `ask` to deny with nobody
        // consulted. Before this fix `answered` always recorded `actor:
        // User, reason: "denied by user"` regardless — indistinguishable
        // from a human who was actually asked and said no. `has_channel:
        // false` must produce a different actor and a reason that says so.
        let r = CapDecisionRecord::answered("wasi:filesystem", "/k", false, false);
        assert_eq!(r.decision, Decision4::AskDeny);
        assert_ne!(
            r.actor,
            Actor::User,
            "nobody was consulted, so this must not be attributed to a user"
        );
        assert_eq!(r.reason.as_deref(), Some("no prompt channel"));
    }

    #[test]
    fn decision4_renders_the_wire_spellings() {
        assert_eq!(Decision4::Allow.to_string(), "allow");
        assert_eq!(Decision4::Deny.to_string(), "deny");
        assert_eq!(Decision4::AskAllow.to_string(), "ask-allow");
        assert_eq!(Decision4::AskDeny.to_string(), "ask-deny");
    }

    #[test]
    fn decision4_marks_which_records_print_immediately() {
        // Allows are batched into the rollup; everything else is an exception
        // that must reach the operator the moment it resolves.
        assert!(!Decision4::Allow.is_exception());
        assert!(Decision4::Deny.is_exception());
        assert!(Decision4::AskAllow.is_exception());
        assert!(Decision4::AskDeny.is_exception());
    }

    #[test]
    fn sha256_hex_matches_the_known_empty_digest() {
        assert_eq!(
            sha256_hex(b""),
            "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
        );
    }

    #[test]
    fn transport_and_outcome_render_lowercase_kebab() {
        assert_eq!(Transport::Cli.to_string(), "cli");
        assert_eq!(Transport::Mcp.to_string(), "mcp");
        assert_eq!(Outcome::Ok.to_string(), "ok");
        assert_eq!(Outcome::ToolError.to_string(), "tool-error");
        assert_eq!(Outcome::HostError.to_string(), "host-error");
        assert_eq!(Outcome::Cancelled.to_string(), "cancelled");
    }
}