polyc-crypto 2026.8.0

//! Remembered-approval **grant** canonicals and their verification path.
//!
//! A grant is the highest-privilege artifact in the system: it clears an egress
//! gate on an unattended run with no human present. ADR 0001 makes it
//! unforgeable by the platform — the only signature that mints one comes from
//! the principal's passkey (a `WebAuthn` assertion whose challenge binds the grant
//! canonical), verified here against the public key registered at enrollment.
//! **There is no code path that mints a signed grant from a platform ed25519
//! key.** [`signed_grant_payload`] assembles the passkey-proof payload;
//! [`verify_grant`] is the only acceptance path.
//!
//! Three canonicals live here, each with a distinct `kind` tag so the audit
//! trail can never confuse them:
//!
//! * **grant** ([`grant_canonical`]) — key `(principal, routine, tool)` plus the
//!   coverage record; passkey-signed.
//! * **revocation** ([`revocation_canonical`]) — the principal's own withdrawal;
//!   a fresh passkey assertion binding the grant's [`grant_ref`].
//! * **suspension** ([`suspension_canonical`]) — the platform's act; ed25519,
//!   the existing [`Signer`], binding the same [`grant_ref`], never requiring
//!   the passkey (a lost passkey cannot strand a live grant).
//!
//! [`live_grant`] is the single fold that treats a grant with a matching
//! verified revocation or suspension as absent — the one place "revoked or
//! suspended ⇒ absent" lives.
//!
//! The canonical style mirrors [`crate::approval`] and [`crate::mandate`]
//! (canonical JSON, a literal `kind` tag first). A revocation/suspension
//! references the exact grant by [`grant_ref`] — the sha256 of the grant's full
//! signed payload — the same chain-link pattern as [`crate::mandate::mandate_hash`].

use serde::Serialize;
use serde_json::Value;
use sha2::{Digest, Sha256};

use base64::Engine as _;
use base64::engine::general_purpose::URL_SAFE_NO_PAD;

use crate::signed::{Envelope, canonical_bytes};
use crate::{Signer, verify};
use polyc_passkey::derive::verify_derived_signature;
use polyc_passkey::{Assertion, WebAuthnProof, challenge_b64, verify_assertion};

/// Signed `kind` tag for a routine-grant canonical.
pub const GRANT_KIND: &str = "grant.routine.v1";
/// Signed `kind` tag for a revocation-tombstone canonical.
pub const REVOCATION_KIND: &str = "grant.revocation.v1";
/// Signed `kind` tag for a suspension canonical.
pub const SUSPENSION_KIND: &str = "grant.suspension.v1";
/// Signed `kind` tag for a routine-grant canonical signed by a persona's
/// recorded signing credential rather than a per-enrollment `WebAuthn` passkey.
///
/// Deliberately distinct from [`GRANT_KIND`] — same kind-per-artifact
/// discipline the module doc describes — so a persona-signed grant can never
/// verify as, or be confused with, a `WebAuthn`-signed one in the audit
/// trail (#1197).
pub const GRANT_PERSONA_KIND: &str = "grant.routine.persona.v1";
/// Signed `kind` tag for a persona-signed revocation tombstone.
///
/// Mirrors [`GRANT_PERSONA_KIND`]'s distinction for [`REVOCATION_KIND`] (#1197).
pub const REVOCATION_PERSONA_KIND: &str = "grant.revocation.persona.v1";

/// A persona-derived-key signature over a grant-family canonical (#1197): the
/// signing key's public bytes plus its plain ed25519 signature.
///
/// The persona-signing sibling of [`WebAuthnProof`] — bundled the same way,
/// so [`signed_grant_payload_persona`]/[`signed_revocation_payload_persona`]
/// stay at the same argument count their `WebAuthn` siblings are.
#[derive(Debug, Clone, Copy)]
pub struct PersonaProof<'a> {
    /// The persona's currently recorded `PersonaCredential.signing_public_key`.
    pub signing_public_key: &'a [u8],
    /// That key's plain ed25519 signature over the canonical directly (no
    /// `WebAuthn` challenge/assertion wrapping).
    pub signature: &'a [u8],
}

/// The coverage record a grant binds: the pinned destination, the slot-schema
/// hash, and the covered capabilities.
///
/// Borrowed so a caller can build it from decoded fields without copying.
/// `slot_schema_hash` is #618's template-coverage hash; `covered_capabilities`
/// are stable kebab-case `polyc_capability` names (the consumer resolves them
/// with `CapabilitySet::from_names`, which is fail-closed on unknown names).
/// Changing the destination or the slot-schema hash changes the canonical, so a
/// coverage drift voids the grant — a new approval ceremony is required.
#[derive(Debug, Clone, Copy)]
pub struct GrantCoverage<'a> {
    /// The pinned egress destination the grant covers.
    ///
    /// **Canonicalization contract:** the compact JSON of the template's
    /// destination map serialized from a `BTreeMap` (key-sorted, no
    /// whitespace). Coverage equality is byte equality of this string, so the
    /// mint side (the enrollment ceremony) and every verify side (the dispatch
    /// resolver recomputing current coverage) MUST produce it the same way —
    /// always `serde_json::to_string` of the `BTreeMap` destination, never a
    /// hand-built string. A formatting-only difference reads as coverage drift
    /// and voids the grant.
    pub destination: &'a str,
    /// The content-template slot-schema hash the grant covers (#618).
    pub slot_schema_hash: &'a str,
    /// The stable kebab-case capability names the grant covers.
    pub covered_capabilities: &'a [String],
}

/// The canonical bytes the passkey challenge binds for a routine grant.
///
/// Key `(principal, routine, tool)` plus the coverage record, the
/// `enrollment_id`, and `created_at_ms`. A byte-level change to any field
/// changes these bytes, hence the [`challenge_b64`] the assertion must carry,
/// so verification fails — this is the single source the ceremony (#621) and
/// the gate (#594) both reproduce.
#[must_use]
pub fn grant_canonical(
    principal: &str,
    routine: &str,
    tool: &str,
    coverage: &GrantCoverage<'_>,
    enrollment_id: &str,
    created_at_ms: u64,
) -> Vec<u8> {
    canonical_bytes(&GrantCanonical {
        kind: GRANT_KIND,
        principal,
        routine,
        tool,
        destination: coverage.destination,
        slot_schema_hash: coverage.slot_schema_hash,
        covered_capabilities: coverage.covered_capabilities,
        enrollment_id,
        created_at_ms,
    })
}

/// The signed grant field set, in its frozen order.
///
/// Shared by [`grant_canonical`] and [`grant_canonical_persona`] — the two
/// differ only in the `kind` tag, so one declaration governs both orders and
/// they cannot drift apart. Declaration order IS the signed contract: it
/// determines the [`grant_challenge`] a passkey assertion binds, so reordering
/// a field voids every grant ever minted. See ADR 0009.
#[derive(Serialize)]
struct GrantCanonical<'a> {
    kind: &'static str,
    principal: &'a str,
    routine: &'a str,
    tool: &'a str,
    destination: &'a str,
    slot_schema_hash: &'a str,
    covered_capabilities: &'a [String],
    enrollment_id: &'a str,
    created_at_ms: u64,
}

/// The signed revocation-tombstone field set, in its frozen order.
///
/// Shared by [`revocation_canonical`] and [`revocation_canonical_persona`],
/// which differ only in the `kind` tag. See ADR 0009.
#[derive(Serialize)]
struct RevocationCanonical<'a> {
    kind: &'static str,
    grant_ref: &'a str,
    revoked_at_ms: u64,
}

/// The signed suspension field set, in its frozen order.
///
/// The body [`suspension_payload`] seals into an [`Envelope`] — so the
/// canonical the signature covers and the persisted payload share one
/// declaration of the field list rather than the two hand-maintained copies
/// this replaced (`#1845`). See ADR 0009.
#[derive(Serialize)]
struct SuspensionCanonical<'a> {
    kind: &'static str,
    grant_ref: &'a str,
    reason: &'a str,
    suspended_at_ms: u64,
}

/// The `WebAuthn` challenge a grant-family canonical binds:
/// `base64url(sha256(canonical))` (url-safe, no pad).
///
/// The value the ceremony page passes to `navigator.credentials.get`, and what
/// every verifier recomputes. A thin alias over [`challenge_b64`] named for the
/// grant family — grants and revocations both derive their challenge here, so
/// the derivation cannot drift between the two ceremonies.
#[must_use]
pub fn grant_challenge(canonical: &[u8]) -> String {
    challenge_b64(canonical)
}

/// The sha256-hex of a grant's **full signed payload** — the reference a
/// revocation or suspension binds.
///
/// Hashing the full payload (canonical fields *and* the assertion) commits to
/// one exact, already-minted artifact, exactly as
/// [`crate::mandate::mandate_hash`] does: a grant re-minted with a different
/// assertion produces a different `grant_ref`, so a stale tombstone cannot void
/// it. Callers (#594/#623) compute this over the stored payload bytes to match
/// a tombstone/suspension to its grant.
#[must_use]
pub fn grant_ref(signed_grant_payload: &[u8]) -> String {
    crate::hex::lower(&Sha256::digest(signed_grant_payload))
}

/// Assemble the full signed grant payload from the canonical fields and a
/// verified-shape `WebAuthn` proof.
///
/// This is the **only** constructor of a signed grant (ADR 0001): the proof is
/// a passkey assertion, never a platform signature. The ceremony (#621) calls
/// this after [`verify_grant`] accepts the freshly minted assertion, then
/// persists the returned bytes as the `routine_grant` event payload. The
/// assertion fields are carried as url-safe base64.
#[must_use]
pub fn signed_grant_payload(
    principal: &str,
    routine: &str,
    tool: &str,
    coverage: &GrantCoverage<'_>,
    enrollment_id: &str,
    created_at_ms: u64,
    proof: &WebAuthnProof<'_>,
) -> Vec<u8> {
    let canonical = grant_canonical(
        principal,
        routine,
        tool,
        coverage,
        enrollment_id,
        created_at_ms,
    );
    attach_proof(&canonical, proof)
}

/// Append a `WebAuthn` proof's four fields to a grant-family canonical,
/// producing the full signed payload.
///
/// Parses `canonical` back into a JSON object and inserts
/// `credential_id`/`authenticator_data`/`client_data_json`/`signature` (each
/// url-safe base64, no padding), then reserializes. Both
/// [`signed_grant_payload`] and [`signed_revocation_payload`] build their
/// canonical fields once (via [`grant_canonical`] / [`revocation_canonical`])
/// and delegate the proof-attachment step here, so a payload can never carry
/// fields that diverge from its own canonical.
///
/// Byte-for-byte compatible with the previous single hand-written `json!`
/// construction regardless of whether `serde_json`'s `preserve_order` feature
/// is active for this build (this crate does not request it, but cargo
/// feature unification can switch it on when another workspace member does):
/// a `BTreeMap`-backed object always resorts keys alphabetically no matter
/// the insertion order, and an order-preserving map always appends genuinely
/// new keys at the end — so parse-then-insert reproduces exactly what
/// building all fields in one macro call would have, under either
/// configuration.
///
/// **That equivalence is per-configuration, not across configurations.** This
/// function round-trips its input through a [`serde_json::Map`], so the bytes
/// it returns still track whichever map type the build resolved: sorted keys
/// under a lean selection, canonical-then-appended under `preserve_order`.
/// `#1845` made the *canonical* build-graph-independent — which is what
/// [`grant_challenge`] hashes, so passkey and persona verification are now
/// independent of the build graph — but the assembled payload is not, and
/// [`grant_ref`] is the sha256 of that payload. Nothing signs or verifies
/// against the payload's own bytes, and no deployment has ever minted a grant
/// (this module is unwired), so nothing is broken today. Because `grant_ref` is
/// always taken over *stored* bytes, a minted grant keeps a stable ref forever;
/// the only divergence is two binaries minting the same logical grant, which
/// cannot happen for a once-minted artifact.
///
/// Sealing the proof fields through a declared struct the way
/// [`suspension_payload`] does closes it, and `#1959` tracks that as a blocker
/// on the grant ceremony rather than a follow-up to it: today there are zero
/// durable bytes to preserve, so the fix is free, and the first mint makes it
/// impossible forever.
fn attach_proof(canonical: &[u8], proof: &WebAuthnProof<'_>) -> Vec<u8> {
    // canonical-allow: a grant payload's key order tracks the build's map type,
    // which is the residual `#1959` tracks. It is annotated rather than fixed
    // here because nothing has ever minted a grant, so no bytes are at risk;
    // see the doc comment above for why the fix must precede the first mint.
    let mut map: serde_json::Map<String, Value> =
        serde_json::from_slice(canonical).expect("a grant-family canonical is a JSON object");
    map.insert(
        "credential_id".to_owned(),
        Value::String(b64(proof.credential_id)),
    );
    map.insert(
        "authenticator_data".to_owned(),
        Value::String(b64(proof.authenticator_data)),
    );
    map.insert(
        "client_data_json".to_owned(),
        Value::String(b64(proof.client_data_json)),
    );
    map.insert("signature".to_owned(), Value::String(b64(proof.signature)));
    Value::Object(map).to_string().into_bytes() // canonical-allow: see `#1959` above
}

/// Verify the passkey proof carried in a grant-family payload against the
/// canonical it claims to bind.
///
/// The shared verification skeleton of [`verify_grant`] and
/// [`verify_revocation`]: base64-decode the three assertion fields off the
/// payload object, derive the expected challenge from `canonical`, and run
/// [`verify_assertion`]. Each public verifier keeps only its own kind check,
/// field extraction, and canonical rebuild. Fail-closed: `None` on any
/// missing field, bad base64, or assertion failure. [`verify_assertion`]'s
/// `sign_count` is discarded here — this crate enforces no counter policy
/// today; a future consumer that wants it reads [`verify_assertion`] directly.
fn verify_passkey_proof(
    v: &Value,
    canonical: &[u8],
    registered_pubkey_sec1: &[u8],
    rp_id: &str,
    origin: &str,
) -> Option<()> {
    let authenticator_data = b64_decode(v.get("authenticator_data")?.as_str()?)?;
    let client_data_json = b64_decode(v.get("client_data_json")?.as_str()?)?;
    let signature = b64_decode(v.get("signature")?.as_str()?)?;
    let assertion = Assertion {
        authenticator_data: &authenticator_data,
        client_data_json: &client_data_json,
        signature: &signature,
    };
    verify_assertion(
        registered_pubkey_sec1,
        &assertion,
        &grant_challenge(canonical),
        rp_id,
        origin,
    )
    .ok()
    .map(|_checks| ())
}

/// Append a [`PersonaProof`]'s two fields to a grant-family canonical,
/// producing the full signed payload.
///
/// The persona-signing sibling of [`attach_proof`]: a persona-derived key
/// signs the canonical directly (a plain ed25519 signature, no `WebAuthn`
/// assertion wrapping — the `WebAuthn` ceremony already ran once, at
/// `PersonaCredential` enrollment, to bind this key), so there is no
/// `authenticator_data`/`client_data_json` to carry, only the raw signature
/// and the signing key it claims to be from (#1197). Shares
/// [`attach_proof`]'s per-configuration byte-equivalence caveat.
fn attach_persona_proof(canonical: &[u8], proof: &PersonaProof<'_>) -> Vec<u8> {
    // canonical-allow: the same residual as `attach_proof`, tracked by `#1959`.
    let mut map: serde_json::Map<String, Value> =
        serde_json::from_slice(canonical).expect("a grant-family canonical is a JSON object");
    map.insert(
        "signing_public_key".to_owned(),
        Value::String(b64(proof.signing_public_key)),
    );
    map.insert("signature".to_owned(), Value::String(b64(proof.signature)));
    Value::Object(map).to_string().into_bytes() // canonical-allow: see `#1959` above
}

/// Verify the persona-signed proof carried in a grant-family payload against
/// the canonical it claims to bind.
///
/// The persona-signing sibling of [`verify_passkey_proof`]: decodes
/// `signing_public_key`/`signature`, checks the payload's claimed signing key
/// equals `expected_persona_pubkey` (the SAME pinning discipline
/// [`verify_suspension`]'s `expected_platform_key` uses — a payload's
/// self-claimed key is never trusted on its own, only a caller-supplied
/// expected one), then verifies the signature via
/// [`verify_derived_signature`] — a plain ed25519 check, matching exactly
/// what a browser's PRF-derived key actually signs with (see
/// [`verify_derived_signature`]'s own docs on why this must NOT be
/// `commonware_cryptography`'s namespaced verify). Fail-closed: `None` on any
/// missing field, bad base64, key mismatch, or signature mismatch.
fn verify_persona_proof(v: &Value, canonical: &[u8], expected_persona_pubkey: &[u8]) -> Option<()> {
    let signing_public_key = b64_decode(v.get("signing_public_key")?.as_str()?)?;
    let signature = b64_decode(v.get("signature")?.as_str()?)?;
    if signing_public_key != expected_persona_pubkey {
        return None;
    }
    if verify_derived_signature(&signing_public_key, canonical, &signature) {
        Some(())
    } else {
        None
    }
}

/// The canonical bytes a persona-signed grant's signature binds.
///
/// The persona-signing sibling of [`grant_canonical`], identical fields,
/// distinguished only by [`GRANT_PERSONA_KIND`] so the two can never verify
/// as each other (#1197).
#[must_use]
pub fn grant_canonical_persona(
    principal: &str,
    routine: &str,
    tool: &str,
    coverage: &GrantCoverage<'_>,
    enrollment_id: &str,
    created_at_ms: u64,
) -> Vec<u8> {
    canonical_bytes(&GrantCanonical {
        kind: GRANT_PERSONA_KIND,
        principal,
        routine,
        tool,
        destination: coverage.destination,
        slot_schema_hash: coverage.slot_schema_hash,
        covered_capabilities: coverage.covered_capabilities,
        enrollment_id,
        created_at_ms,
    })
}

/// Assemble the full signed grant payload from the canonical fields and a
/// [`PersonaProof`].
///
/// The persona-signing sibling of [`signed_grant_payload`] (#1197):
/// `proof.signing_public_key` is the persona's currently recorded
/// `PersonaCredential.signing_public_key`; `proof.signature` is that key's
/// plain ed25519 signature over [`grant_canonical_persona`]'s bytes directly
/// (no `WebAuthn` challenge/assertion wrapping).
#[must_use]
pub fn signed_grant_payload_persona(
    principal: &str,
    routine: &str,
    tool: &str,
    coverage: &GrantCoverage<'_>,
    enrollment_id: &str,
    created_at_ms: u64,
    proof: &PersonaProof<'_>,
) -> Vec<u8> {
    let canonical = grant_canonical_persona(
        principal,
        routine,
        tool,
        coverage,
        enrollment_id,
        created_at_ms,
    );
    attach_persona_proof(&canonical, proof)
}

/// Verify a persisted persona-signed `routine_grant` payload.
///
/// The persona-signing sibling of [`verify_grant`] (#1197). Recomputes
/// [`grant_canonical_persona`] from the payload's own fields and verifies the
/// persona proof against `expected_persona_pubkey` — the
/// persona's CURRENTLY recorded `PersonaCredential.signing_public_key`,
/// looked up live by the caller (never trusted from the payload itself, and
/// never snapshotted at grant-mint time) so a later credential revocation is
/// reflected on every subsequent verification of every grant that credential
/// ever signed — the cascading-revocation property #1197 intentionally
/// chose over per-grant-independent revocation. Returns `None` fail-closed
/// on any malformed field, bad base64, key mismatch, or signature failure.
#[must_use]
pub fn verify_persona_signed_grant(
    payload: &[u8],
    expected_persona_pubkey: &[u8],
) -> Option<VerifiedGrant> {
    let v: Value = serde_json::from_slice(payload).ok()?;
    if v.get("kind")?.as_str()? != GRANT_PERSONA_KIND {
        return None;
    }
    let principal = v.get("principal")?.as_str()?.to_owned();
    let routine = v.get("routine")?.as_str()?.to_owned();
    let tool = v.get("tool")?.as_str()?.to_owned();
    let destination = v.get("destination")?.as_str()?.to_owned();
    let slot_schema_hash = v.get("slot_schema_hash")?.as_str()?.to_owned();
    let covered_capabilities: Vec<String> = v
        .get("covered_capabilities")?
        .as_array()?
        .iter()
        .map(|c| c.as_str().map(str::to_owned))
        .collect::<Option<Vec<_>>>()?;
    let enrollment_id = v.get("enrollment_id")?.as_str()?.to_owned();
    let created_at_ms = v.get("created_at_ms")?.as_u64()?;

    let coverage = GrantCoverage {
        destination: &destination,
        slot_schema_hash: &slot_schema_hash,
        covered_capabilities: &covered_capabilities,
    };
    let canonical = grant_canonical_persona(
        &principal,
        &routine,
        &tool,
        &coverage,
        &enrollment_id,
        created_at_ms,
    );
    verify_persona_proof(&v, &canonical, expected_persona_pubkey)?;

    Some(VerifiedGrant {
        principal,
        routine,
        tool,
        destination,
        slot_schema_hash,
        covered_capabilities,
        enrollment_id,
        created_at_ms,
        grant_ref: grant_ref(payload),
        registered_public_key: expected_persona_pubkey.to_vec(),
    })
}

/// A grant whose passkey assertion verified against the registered key.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct VerifiedGrant {
    /// The principal the grant is scoped to (a persona id — matched against the
    /// turn's caller for isolation, the same rule as
    /// [`crate::approval::is_session_grant_for`]).
    pub principal: String,
    /// The routine the grant belongs to.
    pub routine: String,
    /// The tool the grant covers.
    pub tool: String,
    /// The pinned egress destination the grant covers.
    pub destination: String,
    /// The content-template slot-schema hash the grant covers.
    pub slot_schema_hash: String,
    /// The stable kebab-case capability names the grant covers.
    pub covered_capabilities: Vec<String>,
    /// The enrollment this grant was minted in.
    pub enrollment_id: String,
    /// Milliseconds since the Unix epoch the grant was created.
    pub created_at_ms: u64,
    /// The sha256-hex of the full signed payload — the [`grant_ref`] a
    /// revocation or suspension binds.
    pub grant_ref: String,
    /// The SEC1 registered public key the assertion verified against.
    pub registered_public_key: Vec<u8>,
}

/// Verify a persisted `routine_grant` payload against a registered passkey.
///
/// Recomputes the grant canonical from the payload's own fields, derives the
/// expected [`grant_challenge`], and runs [`verify_assertion`] against
/// `registered_pubkey_sec1` for `rp_id` / `origin`. A byte-level change to ANY
/// canonical-bound field changes the challenge and fails the assertion; a grant
/// signed by a different passkey, or verified against a different registered
/// key, fails. Returns `None` fail-closed on any malformed field, bad base64,
/// or verification failure.
#[must_use]
pub fn verify_grant(
    payload: &[u8],
    registered_pubkey_sec1: &[u8],
    rp_id: &str,
    origin: &str,
) -> Option<VerifiedGrant> {
    let v: Value = serde_json::from_slice(payload).ok()?;
    if v.get("kind")?.as_str()? != GRANT_KIND {
        return None;
    }
    let principal = v.get("principal")?.as_str()?.to_owned();
    let routine = v.get("routine")?.as_str()?.to_owned();
    let tool = v.get("tool")?.as_str()?.to_owned();
    let destination = v.get("destination")?.as_str()?.to_owned();
    let slot_schema_hash = v.get("slot_schema_hash")?.as_str()?.to_owned();
    let covered_capabilities: Vec<String> = v
        .get("covered_capabilities")?
        .as_array()?
        .iter()
        .map(|c| c.as_str().map(str::to_owned))
        .collect::<Option<Vec<_>>>()?;
    let enrollment_id = v.get("enrollment_id")?.as_str()?.to_owned();
    let created_at_ms = v.get("created_at_ms")?.as_u64()?;

    let coverage = GrantCoverage {
        destination: &destination,
        slot_schema_hash: &slot_schema_hash,
        covered_capabilities: &covered_capabilities,
    };
    let canonical = grant_canonical(
        &principal,
        &routine,
        &tool,
        &coverage,
        &enrollment_id,
        created_at_ms,
    );
    verify_passkey_proof(&v, &canonical, registered_pubkey_sec1, rp_id, origin)?;

    Some(VerifiedGrant {
        principal,
        routine,
        tool,
        destination,
        slot_schema_hash,
        covered_capabilities,
        enrollment_id,
        created_at_ms,
        grant_ref: grant_ref(payload),
        registered_public_key: registered_pubkey_sec1.to_vec(),
    })
}

/// The canonical bytes a revocation tombstone's passkey challenge binds.
///
/// Binds the [`grant_ref`] of the grant being withdrawn and the revocation
/// time. A distinct `kind` tag ([`REVOCATION_KIND`]) keeps it separable from a
/// grant in the audit trail.
#[must_use]
pub fn revocation_canonical(grant_ref: &str, revoked_at_ms: u64) -> Vec<u8> {
    canonical_bytes(&RevocationCanonical {
        kind: REVOCATION_KIND,
        grant_ref,
        revoked_at_ms,
    })
}

/// Assemble the full signed revocation payload from a `WebAuthn` proof.
///
/// The principal's own act (ADR 0001 / CONTEXT.md): a fresh passkey assertion
/// over the revocation's own [`grant_challenge`]. Symmetric with
/// [`signed_grant_payload`].
#[must_use]
pub fn signed_revocation_payload(
    grant_ref: &str,
    revoked_at_ms: u64,
    proof: &WebAuthnProof<'_>,
) -> Vec<u8> {
    let canonical = revocation_canonical(grant_ref, revoked_at_ms);
    attach_proof(&canonical, proof)
}

/// A revocation tombstone whose passkey assertion verified.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct VerifiedRevocation {
    /// The [`grant_ref`] this tombstone voids.
    pub grant_ref: String,
    /// Milliseconds since the Unix epoch the grant was revoked.
    pub revoked_at_ms: u64,
    /// The SEC1 registered public key the assertion verified against.
    pub registered_public_key: Vec<u8>,
}

/// Verify a persisted `grant_revocation` payload against a registered passkey.
///
/// Recomputes the revocation canonical, derives the expected challenge, and
/// runs [`verify_assertion`]. Returns `None` fail-closed on any malformed
/// field, bad base64, or verification failure — including a tombstone signed by
/// a passkey other than the one that minted the grant (verified against the
/// caller-supplied registered key).
#[must_use]
pub fn verify_revocation(
    payload: &[u8],
    registered_pubkey_sec1: &[u8],
    rp_id: &str,
    origin: &str,
) -> Option<VerifiedRevocation> {
    let v: Value = serde_json::from_slice(payload).ok()?;
    if v.get("kind")?.as_str()? != REVOCATION_KIND {
        return None;
    }
    let grant_ref = v.get("grant_ref")?.as_str()?.to_owned();
    let revoked_at_ms = v.get("revoked_at_ms")?.as_u64()?;

    let canonical = revocation_canonical(&grant_ref, revoked_at_ms);
    verify_passkey_proof(&v, &canonical, registered_pubkey_sec1, rp_id, origin)?;

    Some(VerifiedRevocation {
        grant_ref,
        revoked_at_ms,
        registered_public_key: registered_pubkey_sec1.to_vec(),
    })
}

/// The canonical bytes a persona-signed revocation tombstone's signature binds.
///
/// The persona-signing sibling of [`revocation_canonical`], identical
/// fields, distinguished only by [`REVOCATION_PERSONA_KIND`] (#1197).
#[must_use]
pub fn revocation_canonical_persona(grant_ref: &str, revoked_at_ms: u64) -> Vec<u8> {
    canonical_bytes(&RevocationCanonical {
        kind: REVOCATION_PERSONA_KIND,
        grant_ref,
        revoked_at_ms,
    })
}

/// Assemble the full signed revocation payload from a [`PersonaProof`].
///
/// The persona-signing sibling of [`signed_revocation_payload`] (#1197).
/// Symmetric with [`signed_grant_payload_persona`].
#[must_use]
pub fn signed_revocation_payload_persona(
    grant_ref: &str,
    revoked_at_ms: u64,
    proof: &PersonaProof<'_>,
) -> Vec<u8> {
    let canonical = revocation_canonical_persona(grant_ref, revoked_at_ms);
    attach_persona_proof(&canonical, proof)
}

/// Verify a persisted persona-signed `grant_revocation` payload.
///
/// The persona-signing sibling of [`verify_revocation`] (#1197).
/// `expected_persona_pubkey` is the persona's CURRENTLY recorded signing
/// key, looked up live by the caller — same cascading-revocation rationale
/// as [`verify_persona_signed_grant`]'s docs.
#[must_use]
pub fn verify_persona_signed_revocation(
    payload: &[u8],
    expected_persona_pubkey: &[u8],
) -> Option<VerifiedRevocation> {
    let v: Value = serde_json::from_slice(payload).ok()?;
    if v.get("kind")?.as_str()? != REVOCATION_PERSONA_KIND {
        return None;
    }
    let grant_ref = v.get("grant_ref")?.as_str()?.to_owned();
    let revoked_at_ms = v.get("revoked_at_ms")?.as_u64()?;

    let canonical = revocation_canonical_persona(&grant_ref, revoked_at_ms);
    verify_persona_proof(&v, &canonical, expected_persona_pubkey)?;

    Some(VerifiedRevocation {
        grant_ref,
        revoked_at_ms,
        registered_public_key: expected_persona_pubkey.to_vec(),
    })
}

/// The canonical (signature-covered) bytes of a suspension.
///
/// Binds the [`grant_ref`], the `reason`, and the suspension time under a
/// distinct `kind` tag ([`SUSPENSION_KIND`]) — so a suspension and a revocation
/// can never be confused in the audit trail even though both bind a `grant_ref`.
#[must_use]
pub fn suspension_canonical(grant_ref: &str, reason: &str, suspended_at_ms: u64) -> Vec<u8> {
    canonical_bytes(&suspension_fields(grant_ref, reason, suspended_at_ms))
}

/// The suspension body both [`suspension_canonical`] and
/// [`suspension_payload`] build, so the signed field list exists once.
const fn suspension_fields<'a>(
    grant_ref: &'a str,
    reason: &'a str,
    suspended_at_ms: u64,
) -> SuspensionCanonical<'a> {
    SuspensionCanonical {
        kind: SUSPENSION_KIND,
        grant_ref,
        reason,
        suspended_at_ms,
    }
}

/// Build a platform-signed (ed25519) suspension payload.
///
/// The platform's act, never the principal's (CONTEXT.md): it reuses the
/// existing [`Signer`] and NEVER requires the passkey, so a lost passkey cannot
/// strand a live grant. `signed_by` / `signature_hex` are appended after
/// signing and are not covered. Returns
/// `(full_payload_bytes, signature_bytes, public_key_bytes)`.
#[must_use]
pub fn suspension_payload(
    grant_ref: &str,
    reason: &str,
    suspended_at_ms: u64,
    signer: &Signer,
) -> (Vec<u8>, Vec<u8>, Vec<u8>) {
    Envelope::seal(
        suspension_fields(grant_ref, reason, suspended_at_ms),
        signer,
    )
}

/// A suspension whose ed25519 signature verified.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct VerifiedSuspension {
    /// The [`grant_ref`] this suspension voids.
    pub grant_ref: String,
    /// The platform's audit reason for the suspension.
    pub reason: String,
    /// Milliseconds since the Unix epoch the grant was suspended.
    pub suspended_at_ms: u64,
    /// The verified platform signer's public key (encoded).
    pub signer_public_key: Vec<u8>,
}

/// Verify a persisted `grant_suspension` payload against the deployment's
/// pinned platform verification key.
///
/// **Trust model:** the caller supplies `expected_platform_key` — the
/// deployment's platform verification key, the one the operator's [`Signer`]
/// corresponds to (never taken from the payload). After decoding, this
/// requires the payload's own `signed_by` key bytes to equal
/// `expected_platform_key` exactly (byte equality; not constant-time, since a
/// public key carries no secret worth guarding against a timing side channel)
/// **before** running the ed25519 verify. A suspension signed by any other
/// key — including a well-formed, self-consistent one from a disposable
/// keypair an attacker controls — is dropped fail-closed: without the pin, a
/// suspension payload carries both its own pubkey and signature, so anyone who
/// can get a suspension-shaped payload accepted could forge one that verifies
/// against itself. Pinning is what makes the audit trail's "the platform did
/// this" claim actually true.
///
/// Rebuilds the suspension canonical and checks the embedded signature via the
/// existing [`verify`]. Returns `None` fail-closed on any malformed field, bad
/// hex, key mismatch, or signature mismatch. The `kind` tag is checked first so
/// a revocation or grant payload can never verify as a suspension.
#[must_use]
pub fn verify_suspension(
    payload: &[u8],
    expected_platform_key: &[u8],
) -> Option<VerifiedSuspension> {
    let v: Value = serde_json::from_slice(payload).ok()?;
    if v.get("kind")?.as_str()? != SUSPENSION_KIND {
        return None;
    }
    let grant_ref = v.get("grant_ref")?.as_str()?.to_owned();
    let reason = v.get("reason")?.as_str()?.to_owned();
    let suspended_at_ms = v.get("suspended_at_ms")?.as_u64()?;
    let pk = crate::hex::decode(v.get("signed_by")?.as_str()?)?;
    let sig = crate::hex::decode(v.get("signature_hex")?.as_str()?)?;
    if pk != expected_platform_key {
        return None;
    }
    let canonical = suspension_canonical(&grant_ref, &reason, suspended_at_ms);
    if verify(&pk, &canonical, &sig) {
        Some(VerifiedSuspension {
            grant_ref,
            reason,
            suspended_at_ms,
            signer_public_key: pk,
        })
    } else {
        None
    }
}

/// The single fold that decides which grant is live.
///
/// Returns the first grant with no matching verified revocation or suspension
/// (matched by [`grant_ref`]); a grant with either is absent. This is the ONE
/// place "revoked or suspended ⇒ absent" lives — #594 (the gate) and #623
/// (re-gating) call it, never reimplement it — so the two paths cannot drift on
/// what counts as live.
#[must_use]
pub fn live_grant<'a>(
    grants: &'a [VerifiedGrant],
    revocations: &[VerifiedRevocation],
    suspensions: &[VerifiedSuspension],
) -> Option<&'a VerifiedGrant> {
    grants.iter().find(|g| {
        !revocations.iter().any(|r| r.grant_ref == g.grant_ref)
            && !suspensions.iter().any(|s| s.grant_ref == g.grant_ref)
    })
}

fn b64(bytes: &[u8]) -> String {
    URL_SAFE_NO_PAD.encode(bytes)
}

fn b64_decode(s: &str) -> Option<Vec<u8>> {
    URL_SAFE_NO_PAD.decode(s).ok()
}

#[cfg(test)]
mod tests {
    #![allow(clippy::pedantic, clippy::nursery, missing_docs)]

    use super::*;
    use polyc_passkey::softkey::SoftPasskey;

    const RP_ID: &str = "enroll.polychrome.test";
    const ORIGIN: &str = "https://enroll.polychrome.test";

    fn caps() -> Vec<String> {
        vec![
            "arbitrary-egress".to_owned(),
            "fixed-connector-read".to_owned(),
        ]
    }

    // Mint a full signed grant with a SoftPasskey over its own challenge — the
    // exact assemble-then-persist flow the ceremony (#621) runs.
    fn mint_grant(key: &SoftPasskey) -> Vec<u8> {
        let covered = caps();
        let coverage = GrantCoverage {
            destination: "slack:T1:C42",
            slot_schema_hash: "sha256:template-abc",
            covered_capabilities: &covered,
        };
        let canonical = grant_canonical(
            "persona-9",
            "standup",
            "post_summary",
            &coverage,
            "enr-1",
            1_700_000_000_000,
        );
        let challenge = grant_challenge(&canonical);
        let signed = key.sign_assertion(&challenge, RP_ID, ORIGIN);
        let proof = WebAuthnProof {
            credential_id: &signed.credential_id,
            authenticator_data: &signed.authenticator_data,
            client_data_json: &signed.client_data_json,
            signature: &signed.signature,
        };
        signed_grant_payload(
            "persona-9",
            "standup",
            "post_summary",
            &coverage,
            "enr-1",
            1_700_000_000_000,
            &proof,
        )
    }

    #[test]
    fn grant_round_trips_and_carries_coverage() {
        let key = SoftPasskey::from_seed(1);
        let payload = mint_grant(&key);
        let g = verify_grant(&payload, &key.public_key_sec1(), RP_ID, ORIGIN).expect("verifies");
        assert_eq!(g.principal, "persona-9");
        assert_eq!(g.routine, "standup");
        assert_eq!(g.tool, "post_summary");
        assert_eq!(g.destination, "slack:T1:C42");
        assert_eq!(g.slot_schema_hash, "sha256:template-abc");
        assert_eq!(g.covered_capabilities, caps());
        assert_eq!(g.enrollment_id, "enr-1");
        assert_eq!(g.grant_ref, grant_ref(&payload));
    }

    #[test]
    fn grant_signed_by_a_different_passkey_is_dropped() {
        let signer = SoftPasskey::from_seed(1);
        let attacker = SoftPasskey::from_seed(2);
        let payload = mint_grant(&signer);
        // Verified against the attacker's registered key ⇒ fail-closed.
        assert!(verify_grant(&payload, &attacker.public_key_sec1(), RP_ID, ORIGIN).is_none());
        // And the genuine key still verifies (control).
        assert!(verify_grant(&payload, &signer.public_key_sec1(), RP_ID, ORIGIN).is_some());
    }

    #[test]
    fn every_canonical_field_including_kind_is_tamper_evident() {
        let key = SoftPasskey::from_seed(3);
        let payload = mint_grant(&key);
        let pk = key.public_key_sec1();
        // Tampering any canonical-bound field changes the challenge the
        // assertion must carry, so verification fails. The proof fields are
        // covered indirectly (a swapped assertion won't match the challenge).
        // `kind` is the one exception: it fails its own explicit equality
        // check in verify_grant before the challenge is ever recomputed, so a
        // grant payload relabeled as a revocation (or any other kind) is
        // rejected on that check instead — still covered by this table so the
        // tamper coverage reads as "every canonical field", not "every field
        // except kind".
        for (field, val) in [
            ("kind", serde_json::json!(REVOCATION_KIND)),
            ("principal", serde_json::json!("persona-EVIL")),
            ("routine", serde_json::json!("other-routine")),
            ("tool", serde_json::json!("exfiltrate")),
            ("destination", serde_json::json!("slack:T1:CEVIL")),
            ("slot_schema_hash", serde_json::json!("sha256:tampered")),
            (
                "covered_capabilities",
                serde_json::json!(["arbitrary-egress", "mutate-external"]),
            ),
            ("enrollment_id", serde_json::json!("enr-2")),
            ("created_at_ms", serde_json::json!(1_700_000_000_001u64)),
        ] {
            let mut v: Value = serde_json::from_slice(&payload).unwrap();
            v[field] = val;
            assert!(
                verify_grant(v.to_string().as_bytes(), &pk, RP_ID, ORIGIN).is_none(),
                "tampered {field} must fail verification"
            );
        }
        // Untampered still verifies.
        assert!(verify_grant(&payload, &pk, RP_ID, ORIGIN).is_some());
    }

    #[test]
    fn grant_ref_is_sensitive_to_the_full_payload() {
        let key = SoftPasskey::from_seed(4);
        let a = mint_grant(&key);
        assert_eq!(grant_ref(&a), grant_ref(&a));
        // A different key mints a different assertion ⇒ a different grant_ref,
        // since it hashes the full signed artifact.
        let b = mint_grant(&SoftPasskey::from_seed(5));
        assert_ne!(grant_ref(&a), grant_ref(&b));
    }

    fn mint_revocation(key: &SoftPasskey, grant_ref_hex: &str, revoked_at_ms: u64) -> Vec<u8> {
        let canonical = revocation_canonical(grant_ref_hex, revoked_at_ms);
        let challenge = grant_challenge(&canonical);
        let signed = key.sign_assertion(&challenge, RP_ID, ORIGIN);
        let proof = WebAuthnProof {
            credential_id: &signed.credential_id,
            authenticator_data: &signed.authenticator_data,
            client_data_json: &signed.client_data_json,
            signature: &signed.signature,
        };
        signed_revocation_payload(grant_ref_hex, revoked_at_ms, &proof)
    }

    #[test]
    fn revocation_round_trips_and_binds_the_grant_ref() {
        let key = SoftPasskey::from_seed(6);
        let payload = mint_grant(&key);
        let gref = grant_ref(&payload);
        let rev = mint_revocation(&key, &gref, 1_700_000_100_000);
        let v = verify_revocation(&rev, &key.public_key_sec1(), RP_ID, ORIGIN).expect("verifies");
        assert_eq!(v.grant_ref, gref);
        assert_eq!(v.revoked_at_ms, 1_700_000_100_000);
        // A tombstone signed by a different passkey is rejected.
        assert!(
            verify_revocation(
                &rev,
                &SoftPasskey::from_seed(7).public_key_sec1(),
                RP_ID,
                ORIGIN
            )
            .is_none()
        );
    }

    #[test]
    fn revocation_tampered_grant_ref_fails() {
        let key = SoftPasskey::from_seed(6);
        let rev = mint_revocation(&key, &"0".repeat(64), 1);
        let mut v: Value = serde_json::from_slice(&rev).unwrap();
        v["grant_ref"] = serde_json::json!("f".repeat(64));
        assert!(
            verify_revocation(
                v.to_string().as_bytes(),
                &key.public_key_sec1(),
                RP_ID,
                ORIGIN
            )
            .is_none()
        );
    }

    #[test]
    fn suspension_round_trips_and_is_tamper_evident() {
        let signer = Signer::from_seed(1);
        let platform_key = signer.public_key_bytes();
        let (payload, _sig, _pk) = suspension_payload(
            "deadbeef",
            "misbehaving routine",
            1_700_000_200_000,
            &signer,
        );
        let v = verify_suspension(&payload, &platform_key).expect("verifies");
        assert_eq!(v.grant_ref, "deadbeef");
        assert_eq!(v.reason, "misbehaving routine");
        assert_eq!(v.suspended_at_ms, 1_700_000_200_000);
        for (field, val) in [
            ("grant_ref", serde_json::json!("cafe")),
            ("reason", serde_json::json!("something else")),
            ("suspended_at_ms", serde_json::json!(0u64)),
        ] {
            let mut t: Value = serde_json::from_slice(&payload).unwrap();
            t[field] = val;
            assert!(
                verify_suspension(t.to_string().as_bytes(), &platform_key).is_none(),
                "tampered {field} must fail"
            );
        }
    }

    #[test]
    fn suspension_signed_by_a_key_other_than_the_expected_platform_key_is_dropped() {
        // A suspension shaped payload carries BOTH its signer's pubkey and
        // signature; without pinning, that pubkey+signature are always
        // self-consistent no matter which key minted them. Anyone who can get
        // a grant_suspension-shaped payload accepted could forge one with a
        // disposable keypair. Pinning `expected_platform_key` closes that:
        // a suspension signed by any key other than the deployment's platform
        // key must be dropped fail-closed, even though it verifies fine
        // against its own embedded key.
        let forger = Signer::from_seed(99);
        let real_platform = Signer::from_seed(1);
        let (payload, _sig, _pk) =
            suspension_payload("deadbeef", "misbehaving routine", 1, &forger);
        assert!(verify_suspension(&payload, &real_platform.public_key_bytes()).is_none());
    }

    #[test]
    fn suspension_signed_by_the_expected_platform_key_round_trips() {
        let platform = Signer::from_seed(1);
        let (payload, _sig, _pk) =
            suspension_payload("deadbeef", "misbehaving routine", 1, &platform);
        assert!(verify_suspension(&payload, &platform.public_key_bytes()).is_some());
    }

    #[test]
    fn live_grant_ignores_a_wrong_key_suspension_and_leaves_the_grant_live() {
        // Fail-closed cuts the OTHER way here than for grants/revocations: a
        // forged suspension (real canonical fields, wrong signer) must be
        // IGNORED, not honored, so the grant stays live. Honoring it would let
        // an attacker holding a disposable keypair suspend (DoS) any grant it
        // can guess a grant_ref for. The pinned check's job isn't to protect
        // availability of the grant — it's to keep the audit trail's "the
        // platform acted" claim true: a suspension record must only ever
        // originate from the platform's actual key, or it doesn't count.
        let key = SoftPasskey::from_seed(20);
        let payload = mint_grant(&key);
        let pk = key.public_key_sec1();
        let grant = verify_grant(&payload, &pk, RP_ID, ORIGIN).unwrap();
        let grants = vec![grant.clone()];

        let forger = Signer::from_seed(99);
        let real_platform = Signer::from_seed(1);
        let (susp_payload, _s, _p) =
            suspension_payload(&grant.grant_ref, "kill switch", 1, &forger);
        // The forged suspension does not verify against the real platform key.
        assert!(verify_suspension(&susp_payload, &real_platform.public_key_bytes()).is_none());
        // So no verified suspension exists to fold in, and the grant is live.
        assert_eq!(live_grant(&grants, &[], &[]), Some(&grants[0]));
    }

    #[test]
    fn revocation_and_suspension_cannot_be_confused() {
        // Distinct kinds: a suspension never verifies as a revocation, and a
        // grant never verifies as a suspension.
        let signer = Signer::from_seed(1);
        let (susp, _s, _p) = suspension_payload("deadbeef", "x", 1, &signer);
        assert!(
            verify_revocation(
                &susp,
                &SoftPasskey::from_seed(1).public_key_sec1(),
                RP_ID,
                ORIGIN
            )
            .is_none()
        );
        let grant = mint_grant(&SoftPasskey::from_seed(1));
        assert!(verify_suspension(&grant, &signer.public_key_bytes()).is_none());
    }

    #[test]
    fn live_grant_folds_revocations_and_suspensions() {
        let key = SoftPasskey::from_seed(8);
        let payload = mint_grant(&key);
        let pk = key.public_key_sec1();
        let grant = verify_grant(&payload, &pk, RP_ID, ORIGIN).unwrap();
        let grants = vec![grant.clone()];

        // No tombstone/suspension ⇒ live.
        assert_eq!(live_grant(&grants, &[], &[]), Some(&grants[0]));

        // Matching revocation ⇒ absent.
        let rev = verify_revocation(
            &mint_revocation(&key, &grant.grant_ref, 1),
            &pk,
            RP_ID,
            ORIGIN,
        )
        .unwrap();
        assert!(live_grant(&grants, std::slice::from_ref(&rev), &[]).is_none());

        // Matching suspension ⇒ absent.
        let platform = Signer::from_seed(1);
        let (susp_payload, _s, _p) =
            suspension_payload(&grant.grant_ref, "kill switch", 1, &platform);
        let susp = verify_suspension(&susp_payload, &platform.public_key_bytes()).unwrap();
        assert!(live_grant(&grants, &[], std::slice::from_ref(&susp)).is_none());

        // A revocation for a DIFFERENT grant_ref leaves this grant live.
        let other = verify_revocation(
            &mint_revocation(&key, &"0".repeat(64), 1),
            &pk,
            RP_ID,
            ORIGIN,
        )
        .unwrap();
        assert_eq!(
            live_grant(&grants, std::slice::from_ref(&other), &[]),
            Some(&grants[0])
        );
    }

    #[test]
    fn garbage_payloads_return_none_not_panic() {
        let pk = SoftPasskey::from_seed(1).public_key_sec1();
        assert!(verify_grant(b"not json", &pk, RP_ID, ORIGIN).is_none());
        assert!(verify_revocation(b"{}", &pk, RP_ID, ORIGIN).is_none());
        assert!(verify_suspension(b"[]", &Signer::from_seed(1).public_key_bytes()).is_none());
    }

    // ── #1197: persona-signed grants (grant-signing credential reuse) ────────

    fn persona_keypair(seed: &[u8]) -> polyc_passkey::derive::SigningKeypair {
        polyc_passkey::derive::derive_signing_keypair(seed)
    }

    // Mint a full persona-signed grant — the exact assemble-then-persist flow
    // the enrollment ceremony runs when the persona already has a recorded
    // signing credential, instead of minting a new per-enrollment passkey.
    fn mint_persona_grant(keypair: &polyc_passkey::derive::SigningKeypair) -> Vec<u8> {
        let covered = caps();
        let coverage = GrantCoverage {
            destination: "slack:T1:C42",
            slot_schema_hash: "sha256:template-abc",
            covered_capabilities: &covered,
        };
        let canonical = grant_canonical_persona(
            "persona-9",
            "standup",
            "post_summary",
            &coverage,
            "enr-1",
            1_700_000_000_000,
        );
        let signature = keypair.sign(&canonical);
        let public_key = keypair.public_key();
        signed_grant_payload_persona(
            "persona-9",
            "standup",
            "post_summary",
            &coverage,
            "enr-1",
            1_700_000_000_000,
            &PersonaProof {
                signing_public_key: &public_key,
                signature: &signature,
            },
        )
    }

    #[test]
    fn persona_grant_round_trips_and_carries_coverage() {
        let keypair = persona_keypair(b"persona-seed-1-------------------");
        let payload = mint_persona_grant(&keypair);
        let g = verify_persona_signed_grant(&payload, &keypair.public_key()).expect("verifies");
        assert_eq!(g.principal, "persona-9");
        assert_eq!(g.routine, "standup");
        assert_eq!(g.tool, "post_summary");
        assert_eq!(g.destination, "slack:T1:C42");
        assert_eq!(g.slot_schema_hash, "sha256:template-abc");
        assert_eq!(g.covered_capabilities, caps());
        assert_eq!(g.enrollment_id, "enr-1");
        assert_eq!(g.grant_ref, grant_ref(&payload));
        assert_eq!(g.registered_public_key, keypair.public_key());
    }

    #[test]
    fn persona_grant_signed_by_a_different_key_is_dropped() {
        let signer = persona_keypair(b"persona-seed-2-------------------");
        let attacker = persona_keypair(b"persona-seed-3-------------------");
        let payload = mint_persona_grant(&signer);
        // Verified against the attacker's key ⇒ fail-closed.
        assert!(verify_persona_signed_grant(&payload, &attacker.public_key()).is_none());
        // The genuine key still verifies (control).
        assert!(verify_persona_signed_grant(&payload, &signer.public_key()).is_some());
    }

    #[test]
    fn persona_grant_every_canonical_field_is_tamper_evident() {
        let keypair = persona_keypair(b"persona-seed-4-------------------");
        let payload = mint_persona_grant(&keypair);
        let pk = keypair.public_key();
        for (field, val) in [
            ("kind", serde_json::json!(REVOCATION_PERSONA_KIND)),
            ("principal", serde_json::json!("persona-EVIL")),
            ("routine", serde_json::json!("other-routine")),
            ("tool", serde_json::json!("exfiltrate")),
            ("destination", serde_json::json!("slack:T1:CEVIL")),
            ("slot_schema_hash", serde_json::json!("sha256:tampered")),
            (
                "covered_capabilities",
                serde_json::json!(["arbitrary-egress", "mutate-external"]),
            ),
            ("enrollment_id", serde_json::json!("enr-2")),
            ("created_at_ms", serde_json::json!(1_700_000_000_001u64)),
        ] {
            let mut v: Value = serde_json::from_slice(&payload).unwrap();
            v[field] = val;
            assert!(
                verify_persona_signed_grant(v.to_string().as_bytes(), &pk).is_none(),
                "tampered {field} must fail verification"
            );
        }
        assert!(verify_persona_signed_grant(&payload, &pk).is_some());
    }

    #[test]
    fn persona_grant_and_webauthn_grant_never_verify_as_each_other() {
        // A persona-signed grant carries GRANT_PERSONA_KIND, not GRANT_KIND —
        // verify_grant (the WebAuthn path) must refuse it outright, and
        // verify_persona_signed_grant must refuse a real WebAuthn-signed
        // grant right back. Distinct kind tags, never confusable, exactly
        // the discipline this module already holds for grant/revocation/
        // suspension.
        let keypair = persona_keypair(b"persona-seed-5-------------------");
        let persona_payload = mint_persona_grant(&keypair);
        assert!(
            verify_grant(
                &persona_payload,
                &SoftPasskey::from_seed(1).public_key_sec1(),
                RP_ID,
                ORIGIN
            )
            .is_none()
        );

        let webauthn_payload = mint_grant(&SoftPasskey::from_seed(1));
        assert!(verify_persona_signed_grant(&webauthn_payload, &keypair.public_key()).is_none());
    }

    #[test]
    fn persona_revocation_round_trips_and_binds_the_grant_ref() {
        let keypair = persona_keypair(b"persona-seed-6-------------------");
        let payload = mint_persona_grant(&keypair);
        let gref = grant_ref(&payload);
        let canonical = revocation_canonical_persona(&gref, 1_700_000_100_000);
        let signature = keypair.sign(&canonical);
        let public_key = keypair.public_key();
        let rev = signed_revocation_payload_persona(
            &gref,
            1_700_000_100_000,
            &PersonaProof {
                signing_public_key: &public_key,
                signature: &signature,
            },
        );
        let v = verify_persona_signed_revocation(&rev, &keypair.public_key()).expect("verifies");
        assert_eq!(v.grant_ref, gref);
        assert_eq!(v.revoked_at_ms, 1_700_000_100_000);
        // A tombstone signed by a different key is rejected.
        let other = persona_keypair(b"persona-seed-7-------------------");
        assert!(verify_persona_signed_revocation(&rev, &other.public_key()).is_none());
    }

    #[test]
    fn persona_grant_and_revocation_can_fold_through_live_grant() {
        // The generic live_grant fold doesn't care which signing method
        // produced a VerifiedGrant/VerifiedRevocation — a persona-signed
        // grant with a persona-signed revocation folds exactly like the
        // WebAuthn-signed pair does.
        let keypair = persona_keypair(b"persona-seed-8-------------------");
        let payload = mint_persona_grant(&keypair);
        let grant = verify_persona_signed_grant(&payload, &keypair.public_key()).unwrap();
        let grants = vec![grant.clone()];
        assert_eq!(live_grant(&grants, &[], &[]), Some(&grants[0]));

        let canonical = revocation_canonical_persona(&grant.grant_ref, 1);
        let signature = keypair.sign(&canonical);
        let public_key = keypair.public_key();
        let rev_payload = signed_revocation_payload_persona(
            &grant.grant_ref,
            1,
            &PersonaProof {
                signing_public_key: &public_key,
                signature: &signature,
            },
        );
        let rev = verify_persona_signed_revocation(&rev_payload, &keypair.public_key()).unwrap();
        assert!(live_grant(&grants, std::slice::from_ref(&rev), &[]).is_none());
    }

    #[test]
    fn persona_grant_garbage_payloads_return_none_not_panic() {
        let pk = persona_keypair(b"persona-seed-9-------------------").public_key();
        assert!(verify_persona_signed_grant(b"not json", &pk).is_none());
        assert!(verify_persona_signed_revocation(b"{}", &pk).is_none());
    }
}

#[cfg(test)]
mod canonical_freeze {
    //! Every signed canonical in this module, frozen as literal bytes (`#1845`).
    //!
    //! These are the bytes a deployment has already signed and has sitting in
    //! its log. They are checked in, never regenerated: regenerating one is the
    //! defect this module exists to catch, because a canonical whose bytes move
    //! invalidates every signature ever minted over the old ones.
    //!
    //! The reason they can be single literals at all is the conversion `#1845`
    //! made, following `#1842`. Before it, each canonical was a
    //! [`serde_json::Value`], whose object is a `BTreeMap` (keys sorted) by
    //! default and an `IndexMap` (insertion order) whenever anything in the
    //! build graph enables `serde_json/preserve_order` — so the same payload
    //! signed by two binaries with different dependency sets produced different
    //! bytes and different signatures. Every literal below is the
    //! insertion-order form, which is what a control-plane binary (where
    //! `preserve_order` is unified in) has always signed. Run this module under
    //! either selection and every literal holds:
    //!
    //! ```text
    //! cargo nextest run -p polyc-crypto                    # no preserve_order
    //! cargo nextest run -p polyc-crypto -p polyc-payments  # preserve_order on
    //! ```
    //!
    //! See ADR 0009 for the decision these literals enforce.
    #![allow(clippy::pedantic, clippy::nursery, missing_docs)]

    use super::*;

    /// Assert a canonical's bytes are exactly the frozen literal.
    fn frozen(label: &str, got: &[u8], want: &str) {
        assert_eq!(
            String::from_utf8(got.to_vec()).unwrap(),
            want,
            "{label}: canonical bytes moved — every signature over the old bytes is now unverifiable"
        );
    }

    const DESTINATION: &str = r#"{"channel":"C1","workspace":"T1"}"#;
    const GRANT_REF: &str = "cafe0123";
    const CREATED_AT_MS: u64 = 1_700_000_000_000;
    const REVOKED_AT_MS: u64 = 1_700_000_100_000;
    const SUSPENDED_AT_MS: u64 = 1_700_000_200_000;
    const REASON: &str = "policy change";

    fn caps() -> Vec<String> {
        vec!["arbitrary-egress".to_owned(), "mutate-external".to_owned()]
    }

    #[test]
    fn grant_canonicals_are_frozen() {
        let caps = caps();
        let coverage = GrantCoverage {
            destination: DESTINATION,
            slot_schema_hash: "sha256:abc",
            covered_capabilities: &caps,
        };
        frozen(
            "grant_canonical",
            &grant_canonical(
                "persona-1",
                "routine-1",
                "paid_fetch",
                &coverage,
                "enr-1",
                CREATED_AT_MS,
            ),
            GRANT_CANONICAL,
        );
        frozen(
            "grant_canonical_persona",
            &grant_canonical_persona(
                "persona-1",
                "routine-1",
                "paid_fetch",
                &coverage,
                "enr-1",
                CREATED_AT_MS,
            ),
            GRANT_PERSONA_CANONICAL,
        );
    }

    #[test]
    fn revocation_canonicals_are_frozen() {
        frozen(
            "revocation_canonical",
            &revocation_canonical(GRANT_REF, REVOKED_AT_MS),
            REVOCATION_CANONICAL,
        );
        frozen(
            "revocation_canonical_persona",
            &revocation_canonical_persona(GRANT_REF, REVOKED_AT_MS),
            REVOCATION_PERSONA_CANONICAL,
        );
    }

    #[test]
    fn suspension_canonical_and_payload_are_frozen() {
        frozen(
            "suspension_canonical",
            &suspension_canonical(GRANT_REF, REASON, SUSPENDED_AT_MS),
            SUSPENSION_CANONICAL,
        );
        let (full, sig, _) =
            suspension_payload(GRANT_REF, REASON, SUSPENDED_AT_MS, &Signer::from_seed(99));
        frozen("suspension_payload", &full, SUSPENSION_PAYLOAD);
        assert_eq!(crate::hex::lower(&sig), SUSPENSION_SIG);
    }

    const GRANT_CANONICAL: &str = r#"{"kind":"grant.routine.v1","principal":"persona-1","routine":"routine-1","tool":"paid_fetch","destination":"{\"channel\":\"C1\",\"workspace\":\"T1\"}","slot_schema_hash":"sha256:abc","covered_capabilities":["arbitrary-egress","mutate-external"],"enrollment_id":"enr-1","created_at_ms":1700000000000}"#;
    const GRANT_PERSONA_CANONICAL: &str = r#"{"kind":"grant.routine.persona.v1","principal":"persona-1","routine":"routine-1","tool":"paid_fetch","destination":"{\"channel\":\"C1\",\"workspace\":\"T1\"}","slot_schema_hash":"sha256:abc","covered_capabilities":["arbitrary-egress","mutate-external"],"enrollment_id":"enr-1","created_at_ms":1700000000000}"#;
    const REVOCATION_CANONICAL: &str =
        r#"{"kind":"grant.revocation.v1","grant_ref":"cafe0123","revoked_at_ms":1700000100000}"#;
    const REVOCATION_PERSONA_CANONICAL: &str = r#"{"kind":"grant.revocation.persona.v1","grant_ref":"cafe0123","revoked_at_ms":1700000100000}"#;
    const SUSPENSION_CANONICAL: &str = r#"{"kind":"grant.suspension.v1","grant_ref":"cafe0123","reason":"policy change","suspended_at_ms":1700000200000}"#;
    const SUSPENSION_PAYLOAD: &str = r#"{"kind":"grant.suspension.v1","grant_ref":"cafe0123","reason":"policy change","suspended_at_ms":1700000200000,"signed_by":"35ccaf567ce385fe73a3d0ef44c04c8e4f13cf02ec853ac430a8bfd40cefe008","signature_hex":"dd7c046496ba66d2fc531bbbdbdc926a3f400a45a399a2c7668a2a59253d067eecfd6447de4b2842d21331db5aa8fc6154776094cc694399b507c0684459ea01"}"#;
    const SUSPENSION_SIG: &str = "dd7c046496ba66d2fc531bbbdbdc926a3f400a45a399a2c7668a2a59253d067eecfd6447de4b2842d21331db5aa8fc6154776094cc694399b507c0684459ea01";
}