Track 5 identity plane: deferred findings from #246

Deferred, non-blocking findings from the Track 5 identity-plane branch (#246). Each was raised by a task or whole-branch review, triaged as fine-to-defer, and recorded rather than fixed, to keep that PR's diff scoped. Grouped by area; none is a known-broken path.

### Entitlement canonicalization (`AgentEntitlementCanonicalizer.swift`)
- [ ] FQN passthrough accepts any `https://…/attr/…/value/…` regardless of namespace, so a foreign-namespace FQN passes through instead of being dropped. The server-side subset check is the real gate, so this is defense-in-depth.
- [ ] `hasPrefix("https://")` is case-sensitive — `HTTPS://…` is silently dropped.
- [ ] Trims `.whitespaces` rather than `.whitespacesAndNewlines`, so `"read\n"` is dropped.

### Identity client (`ArkavoIdentityClient.swift`)
- [ ] Device-check body/response structs are `Encodable`-only / `Decodable`-only rather than full `Codable`. Functionally correct; inconsistent with the rest of the file.
- [ ] No test asserts `Content-Type: application/json` is set on POSTs.
- [ ] The challenge→POST session-cookie reuse cannot be exercised through the `URLProtocol` stub. Verifiable only against a live authnz-rs; the highest residual risk in the branch.

### Agent authorization (`AgentAuthorizationView.swift`, `AgentAuthorizationFlow.swift`, `ContactsCreateView.swift`)
- [ ] `request.name ?? "Authorized Agent"` is defaulted independently in two places; nothing keeps the name sent to the server in sync with the name stored on the local `Profile`.
- [ ] `AgentRPCPairingOutcome.failed` is logged but never surfaced. A user whose local RPC pairing fails after a successful cloud delegation gets no indication they should re-pair.
- [ ] `displayNameForEntitlement` splits on `.`, so a spec-§4.1 FQN payload renders as `Ai/Attr/Action/Value/Read`. The consent list also shows raw values that the canonicalizer will silently drop. Display-only and fails safe (never shows less than is granted), but it will look wrong as soon as Track 4 ships FQNs in QR codes.
- [ ] `ChatsView.swift:446-452` ignores its `AgentQRScannerView` request argument. Pre-existing; would be resolved by restructuring `AgentQRScannerView` into a pure scan-then-hand-off (it currently authorizes inline and calls back only afterwards), which would also touch `ChatsView`.

### Delegations list (`AgentDelegationsView.swift`)
- [ ] Revoking removes the row locally, but the next `load()` reconciles it back as `.revoked` (the server keeps returning it with `revoked: true`), so a pull-to-refresh makes it reappear.
- [ ] A `.notFound` from `revokeDelegation` is treated as success. Reasonable — it mirrors the documented 409-as-success rule for `authorizeAgent` — but that server behavior is assumed client-side, not documented.
- [ ] Error states surface raw server response bodies verbatim in the UI.

### Device attestation (`DeviceAttestationService.swift`, `ArkavoAuthState.swift`)
- [ ] `runLoop()`'s strong `self` keeps the service alive for the loop's lifetime, so `deinit`'s `loopTask?.cancel()` never fires. Harmless for an app-lifetime `@StateObject`, but it means the type cannot be torn down.
- [ ] Refresh-loop failures land only in `@Published lastError`, with no logging and no current reader.
- [ ] The new foreground-return refresh trigger has no test (adding one needs a new test file).
- [ ] `ArkavoAuthState.checkStoredCredentials`'s catch-all clears the device CWT on *any* auto-login failure, including a transient network error. Mirrors the pre-existing human-token behavior on that path, and the App Attest key id survives so it self-heals.

### Pre-existing, found while working nearby
- [ ] **`ArkavoClient.deleteAccount()` can leave the human token in the keychain.** Its human-token clear sits inside `disconnect()`, which returns early on `guard currentState == .connected` — so deleting an account while disconnected never clears it. #246 sidestepped this for the device token and App Attest key id by clearing them directly in `deleteAccount()`, but the human-token hole remains.
- [ ] **`ArkavoClient.swift:611` prints an auth-completion response body containing `ntdf_token` in plaintext.** No new code in #246 logs any token; this one predates it.
- [ ] The full `cd ArkavoKit && swift test` cannot complete headlessly: `NTDFStreamingTests` needs a CoreData XPC store and retries forever (`CoreData: XPC: Unable to connect to server`). The package compiles and links and every other suite passes, so this blocks whole-package CI, not correctness.

### Follow-ups owned elsewhere
- [ ] **App Attest environment is `development` in release builds** (see #246's Known Limitations). Only one `Arkavo.entitlements` exists and both configurations point at it. Needs a build-setting-driven entitlements split.
- [ ] **Revisit `PlatformTokenProvider`'s human-first preference** once authnz-rs extends the device CWT's `aud` to the platform audience and the platform fork's `mode: arkavo` class-ceiling table is deployed (spec §5.2 steps 1-2).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

https://claude.ai/code/session_01PrbFu42oZM4ukgnhBc6dbu

This is a deferred tracking issue covering multiple Swift files, including AgentEntitlementCanonicalizer.swift, ArkavoIdentityClient.swift, AgentAuthorizationView.swift, AgentDelegationsView.swift, and DeviceAttestationService.swift. Start by selecting and splitting out one finding, then read its named file and related tests; done criteria differ for each item and are not defined for the umbrella issue.

Written by the indexing model from the issue text.