# Session authority

The Souveraine session has one authority. `sessiond` receives evidence from the
system, applies Souveraine policy, exposes named verbs, and keeps the trail.
The shell is its face. It is not a second policy engine.

This chapter owns the living architecture. The longer doctrine and audit
records remain in SouveraineOS under `docs/SESSION-AUTHORITY-DOCTRINE.md`,
`docs/SESSION-TRUST-ARCHITECTURE.md`, and `docs/TRUST-BOUNDARY-MATRIX.md`.

## The authority it is, and the authorities it consumes

Classical Linux gives ambient authority to processes sharing a UID. It has
several narrower authorities, but no single object that means "the state and
permission of this person's session." Souveraine does not replace those
authorities with hand-maintained booleans. It consumes them:

- the compositor owns what is presented and the Wayland lock protocol;
- logind owns seat/session facts, `LockedHint`, suspend, shutdown, and
  inhibitors;
- PAM owns authentication;
- Wayland idle protocols own compositor-observed idleness;
- NetworkManager owns link and bearer facts;
- the kernel and their owning daemons own device evidence.

`sessiond` is the one place where those truths become Souveraine policy and
action. A shadow copy is not a second truth. If it can drift from the owner, it
may be a cache with explicit invalidation, but it may not decide.

## Sixty percent agent, forty percent user

The agent owns device operation. If the system can perform an ordinary device
operation, there should be an agent-reachable verb for it. A missing verb is a
defect unless the operation crosses a user-only invariant.

The user uniquely owns being the user: credentials, fresh authentication,
step-up consent, and the decision to cross a boundary whose meaning cannot be
delegated. The user is not required to act as a remote control for mundane
operations merely because the agent's path was never built.

This is the 60/40 split. It is not a percentage implemented in code. It is a
design test for every capability surface.

## Requests are not acknowledgements

The authority distinguishes intent, attempted action, and observed fact.

`screenLocked` can express a request or policy state. `screenLockSecure` means
the compositor has actually established the secure lock. A request to lock is
not permission to blank as though the lock were already held. The dark-panel
path therefore requests lock, waits for acknowledgement within a fixed budget,
and records a security error if the acknowledgement never arrives before the
panel is blanked.

The same rule applies elsewhere:

- starting a systemd unit is not readiness;
- issuing a compositor command is not proof that a surface arrived;
- accepting a socket write is not proof that a state transition committed;
- a green package build is not proof that the device installed or exercised it.

The session start graph and its readiness boundary live in
[session start](../surface/02-session-start.md).

## Capability tiers

Tier is metadata on the verb being guarded, checked at the authority. It is not
a separate permissions subsystem in the shell.

| Tier | Requirement | Typical reach |
|---|---|---|
| `ambient` | no authentication | time, weather, timers, media transport, non-personal questions |
| `personal` | the session is genuinely unlocked | messages, memory, contacts, fleet and conversation state |
| `stepUp` | fresh authentication for the named family | send, delete, publish, payment, physical access, revealing personal content on lock |

Step-up does not unlock the session. It can grant a narrow action family or
reveal content in place on the lock surface. A future grant therefore needs an
action family, freshness, provenance, and expiry; "fingerprint succeeded" is
not itself a session-wide capability.

## Verbs, refusals, and inspection

Every operation exposed by sessiond should have one stable name and one
decision point. The same capability may be rendered as a shell button, a body
tool, or an agent request, but those are clients of the verb, not parallel
implementations.

An authority-grade verb carries enough structure to answer:

- what was requested and by whom;
- what current state and evidence it used;
- which tier and inhibitor applied;
- whether it accepted, refused, or failed;
- what observable acknowledgement completed it;
- what belongs in the forensic trail.

Refusal is data. Stable refusal codes let a face explain, a caller retry only
when retry is meaningful, and the trail distinguish policy from breakage.
`describe` is the inspection surface: clients should not copy a verb list and
guess which actions are live.

## Idle and inhibitors

Idleness is evidence from the compositor, not a timer duplicated in every
surface. Applications and system work can inhibit consequences, but an
inhibitor is scoped, named, and inspectable. It is not a permanent alternate
writer of panel or lock state.

The authority may decide to dim, lock, blank, doze, suspend, or stay awake.
The state machine records that decision and the executor performs the action.
No shell timer, hypridle listener, or device script gets an independent vote.

## The boundary that exists today

The current local session socket is mode `0600` and accepts same-user callers.
That is a useful local boundary, not the eventual attested capability system.
A process running as the user can still reach more than the doctrine intends.

Also not yet true:

- step-up metadata is not wired across send, delete, push, or physical-access
  verbs;
- fingerprint authentication and short-lived reveal grants are not live on
  blueline;
- callers do not present capability tokens or binary attestation;
- every device operation does not yet have a complete `describe`-derived
  control surface;
- refusal and acknowledgement shapes are not yet uniform across every family.

Those are security and control gaps. A polished button does not close them.

## Proof

Keep four claims separate:

1. **source** — the authority and verb exist in the tree;
2. **package** — CI built and signed the owning files and dependencies;
3. **installed** — the device owns those package files and no higher-priority
   local splint shadows them;
4. **exercised** — the real caller, authority, executor, and acknowledgement ran
   on the intended body.

The last is the only proof that a lock was secure, a panel moved, or an action
crossed the boundary it claims.
