lazaret/docs/specification.md

# Lazaret Specification

This document is the normative product specification for Lazaret.

### Document authority

| Document | Authoritative for |
| :--- | :--- |
| This specification | Product north star, trust model, stable vocabulary and identifiers, below-abstraction architecture, and product requirements |
| [TLA+ application protocol model](protocol/Lazaret.tla) and [TLC config](protocol/Lazaret.cfg) | Protocol lifecycle, communication semantics, publication, registration, escalation, recovery, and checked invariants |
| Development journal | Implementation strategy, experiments, and historical rationale (local checkout: [journal index](journal/00_INDEX.md), [implementation plan](journal/implementation-plan.md)) |

This specification does **not** restate the protocol state machine. If a product
requirement needs a protocol rule the model does not yet express, either extend
the model or state that the requirement is outside the current model abstraction.

## 1. Problem Statement

AI coding agents need broad local capabilities: they run arbitrary tools, modify a
project, use Git, install dependencies, and access selected network services. Code
produced or invoked by an agent is not trusted to run directly on the developer's
host. A conventional container reduces risk, but poor terminal behavior, transient
tool state, restricted Git access, and manual setup can make the safe path too
inconvenient for routine work.

Lazaret's north star is:

> Make isolated agent execution the easiest way to work, while ensuring that every
> transition from the sandbox to host authority is explicit, attributable, and
> controlled by the developer.

Lazaret therefore provides a rootless gVisor sandbox with a bidirectionally shared
workspace, persistent sandbox-local tooling, controlled network egress, and a
human-in-the-loop host escalation path.

### 1.1 Trust Model

The following components are trusted:

- The developer and host operating system.
- The Lazaret CLI and the domain's Session Coordinator (Host Coordinator, Runtime
  Supervisor, and attached runsc client).
- Host configuration selected by the developer.
- Domain network-policy installation and connectivity helpers under Runtime
  Supervisor ownership, and the policy Lazaret installs for the Domain.

The following components are untrusted:

- The agent and every process it launches.
- Code, tools, and package installation scripts executed inside the Agent Sandbox.
- Data received from the network by sandboxed processes.

All Client Sessions in the same Domain intentionally share an Agent Sandbox and
are one sandbox trust domain. Session identity distinguishes ownership and routes
terminal interactions; it is not an isolation boundary between processes in that
sandbox.

The Agent Workspace is intentionally writable. Lazaret protects the host outside
the explicitly mounted workspace and volumes. Tracked and ordinary untracked
workspace paths remain writable, while Git-ignored paths are isolated into
Domain-scoped sandbox state by default. The developer may explicitly disable that
isolation in trusted host configuration.

Host configuration is read only by host Lazaret processes. A configuration file
must not be mounted into, or located beneath a host path mounted into, the Agent
Sandbox.

## 2. Glossary

These terms and identifiers are stable across the specification, protocol model,
implementation plan, logs, and user interfaces.

| Term | Definition |
| :--- | :--- |
| **Agent Profile** | A developer-selected host configuration describing an agent image and its granted storage, network, environment, and escalation capabilities. |
| **Agent Workspace** | The canonical host project directory mounted read-write at `/workspace` in the Agent Sandbox. |
| **Agent Sandbox** | The rootless gVisor container in which an agent and its child processes execute. One sandbox is shared by all Client Sessions in a Domain. gVisor sentry, gofer, and guest processes are the sandbox, not the Session Coordinator. |
| **Agent Sandbox ID** | A runtime-unique identifier assigned to one Agent Sandbox instance and bound to its Domain protocol identity. |
| **Client CLI ID** | A runtime-unique identifier assigned to one host Lazaret CLI process. It is authenticated as a protocol identity and bound to one Client Session. |
| **Client Session** | One active host Lazaret CLI process and the interactive or non-interactive command it attaches to the Agent Sandbox. |
| **Session ID** | A cryptographically random identifier unique to one Client Session. |
| **Session Anchor** | Ephemeral session credentials that bind protocol messages to a registered Session ID and route them to the owning host CLI. |
| **Session Coordinator** | The logical Domain role that exclusively owns and coordinates a Domain generation's runtime resources and Client Sessions. It is realized by exactly three constitutive processes: Host Coordinator, Runtime Supervisor, and attached runsc client. |
| **Session Coordinator ID** | A runtime-unique identifier for the logical Session Coordinator as a protocol peer, authenticated on the Host Coordinator face. Generation scoping and stale-credential refuse follow the protocol model. |
| **Host Coordinator** | The constitutive Session Coordinator process that runs in the host user and mount namespaces. It is the protocol face: Domain lock, durable state store, Session PTY masters, escalation mailbox and routing, publication and session admission, and lifetime authority over the Runtime Supervisor. |
| **Runtime Supervisor** | The constitutive Session Coordinator process that runs in the Domain generation's user, mount, and network namespaces under a Host Coordinator lifetime lease. It owns supervised filesystem and network resources for the generation, arms the parent-death edge to attached runsc, and launches the attached runsc client. |
| **Attached runsc** | The constitutive Session Coordinator process that is the non-detached `runsc` client child of the Runtime Supervisor. It supplies the causal coupling edge to the complete Agent Sandbox. |
| **Domain** | The shared runtime and persistent-state scope for one `(Agent Profile, canonical Agent Workspace)` pair. |
| **Domain ID** | A deterministic identifier derived from the Agent Profile name and canonical Agent Workspace path. It namespaces Domain resources but is not an authentication credential. |
| **Domain generation** | One attempt to prepare, publish, operate, and tear down or recover a Domain's transient runtime resources under a single Session Coordinator instance and durable generation identity. |
| **Domain Root** | The host-only directory containing persistent state and metadata for one Domain. |
| **Network Sidecar** | The logical Domain network-policy role for one Domain generation: derived-policy application, enforcement network-namespace preparation, connectivity-helper supervision, and network readiness attestation. Under the selected architecture this role is realized on the Runtime Supervisor-owned install path (with a supervised connectivity helper). It is not a constitutive Session Coordinator process and need not be a separate OS process. The Agent Sandbox never holds network-administration capability. |
| **Network Sidecar ID** | Protocol component identifier for the Domain generation's Network Sidecar role instance (not a Runtime Supervisor or connectivity-helper process id, and not a filesystem path). Generation scoping follows the protocol model. |
| **Connectivity helper** | The supervised process that provides user-space connectivity for the Domain enforcement network namespace. Production uses `slirp4netns`. Ownership and lease coupling follow the protocol model; process identity is product recovery material, not the Network Sidecar ID. |
| **Derived network policy** | The generation-bound policy document Lazaret derives from trusted host configuration (default and profile allow/deny prefixes, DNS reachability, address-family disposition). Only derived policy is installed; the Agent Sandbox never supplies policy. |
| **Network readiness fingerprint** | Product encoding of protocol network readiness: a cryptographic digest over Domain ID, generation, configuration fingerprint, Network Sidecar ID, derived-policy digest, and enforcement network-namespace identity material. |
| **Prepared lower** | A Lazaret-owned immutable root filesystem tree materialised from the selected base image. Content is identified by a prepared-artifact identity. |
| **Prepared-artifact ID** | A Lazaret-assigned identity for one immutable prepared-lower tree (content-addressed or otherwise unique among prepared lowers under the Storage Root). |
| **Prepared-lower lease** | Product binding of a Domain generation to a prepared-artifact ID for State Anchor use (not a container-engine mount refcount). Lease lifecycle follows the protocol model. |
| **Durable intent** | Protocol durable intent that Lazaret intends to create or has created a named external resource for a Domain generation (see protocol model). |
| **Publication** | Protocol publication of a Domain generation for Client Session registration and service (see protocol model). |
| **Git Sentry** | The protective mount layout that preserves bidirectional workspace and Git access while preventing writes to the host's default Git hooks and repository configuration. |
| **Ignored Workspace State** | Domain-scoped sandbox-local storage presented at Git-ignored Agent Workspace paths instead of exposing the corresponding host content. |
| **State Anchor** | The Domain-scoped persistent writable filesystem layer merged over selected paths from the sandbox base image prepared lower. |
| **Trust Anchor** | The ephemeral Domain-scoped certificate authority used to authenticate role-bound Lazaret protocol identities. |
| **Protocol Identity** | An authenticated binding of a component role, Agent Profile, Domain ID, and runtime component ID. Identifiers name components but do not authenticate them by themselves. |
| **Escalation Client** | The Lazaret-provided executable through which a sandboxed process requests a host action. |
| **Escalation Mailbox** | Host-private, Domain-scoped regular-file message paths mounted into the Agent Sandbox for signed escalation requests and correlated results. |
| **Escalation Request ID** | A cryptographically random identifier used to correlate one host escalation request and response. |
| **Escalation Result** | The terminal response to an accepted Host Escalation, correlated by Escalation Request ID and carrying its outcome plus command exit status and output when execution occurred. |
| **Host Escalation** | A request by a sandboxed process for Lazaret to execute a developer-approved or auto-approved action with host authority. |
| **Configuration Fingerprint** | A cryptographic digest of the validated host configuration that created or joined a running Domain. |
| **Storage Root** | The trusted host directory beneath which Lazaret stores Domain Roots and profile-scoped state. |

## 3. Architecture

### 3.1 System Boundaries

```mermaid
flowchart TB
    subgraph Host[Trusted host]
        CLI[Client CLI]
        Config[Host configuration]
        HostWorkspace[Agent Workspace]
        HC[Host Coordinator]
        RS[Runtime Supervisor]
        Runsc[Attached runsc]
        State[State Anchor / FUSE]
        Net[Network policy + connectivity helper]
        Mailbox[Escalation Mailbox]
        HostExec[Approved host process]
    end

    subgraph Sandbox[Untrusted Agent Sandbox - rootless gVisor]
        Agent[Agent and child processes]
        Workspace[/workspace mount]
        Escalate[Escalation Client]
    end

    Config --> CLI
    HostWorkspace <--> Workspace
    CLI <--> HC
    HC --> RS
    RS --> Runsc
    Runsc --> Sandbox
    RS --> State
    RS --> Net
    HC <--> Mailbox
    Agent <--> Workspace
    Agent --> Escalate
    Escalate <--> Mailbox
    HC --> HostExec
    Agent --> Net
    Net --> Network[Permitted destinations]
```

The logical Session Coordinator for a Domain generation is the composition of the
Host Coordinator, Runtime Supervisor, and attached runsc client. The Host
Coordinator is the sole protocol and session face for Client CLIs. The Runtime
Supervisor owns generation-bound runtime namespaces and supervised resources. The
attached runsc client is the non-detached causal edge to the Agent Sandbox.

The Agent Sandbox uses gVisor's application-kernel isolation under rootless
operation. Lazaret owns sandbox lifetime through the Session Coordinator process
chain; an external container engine does not own the Domain's Agent Sandbox.
Rootless operation limits the host authority of runtime helpers, while gVisor
interposes a separate userspace kernel between untrusted processes and the host
kernel. Network policy installation and connectivity helpers are trusted and are
not part of the untrusted agent environment.

Lazaret is daemonless: it does not require a persistent global Unix service or
cross-Domain runtime authority that survives independently of Domain generations.
Active Domains have per-generation and per-session processes whose authority is
scoped by Domain ID, generation, configuration fingerprint, role identity, and
exact physical ownership. Bootstrap recovery for a Domain is initiated by a host
Lazaret CLI invocation for that Domain, not by a resident scheduler.

### 3.2 Domain and Session Lifecycle

One logical Session Coordinator exclusively owns a Domain generation's Agent
Sandbox, Network Sidecar resources, State Anchor mounts, host-only sockets,
Escalation Mailbox, durable generation state, and active-session registry.
Concurrent CLI processes for the same Domain join the published Host Coordinator
and attach separate Client Sessions to the shared sandbox. Different Domains never
share these resources.

An exclusive non-blocking Domain lock elects at most one Host Coordinator startup
or recovery leader for a Domain. Losers fail closed. Client CLIs start, join, or
recover a Domain through that lock and publication rather than a global control
plane.

Protocol lifecycle—startup, registration, cancellation, recovery, teardown,
publication, escalation, generation-scoped identities, durable intent, network
readiness, prepared-lower lease, and connectivity-helper ownership—is defined by
the [TLA+ application protocol model](protocol/Lazaret.tla). Product
implementation refines that model with physical resources (prepared-lower trees,
mounts, `slirp4netns`, PTYs, runsc clients, durable store encoding, exact
ownership records) and must not assume those resources disappeared with an owner
process.

Session control and escalation use the Session Coordinator ID on the Host
Coordinator face, not Runtime Supervisor, attached runsc, or connectivity-helper
process identifiers. Network attachment uses the Network Sidecar ID as the
generation's network-policy role identity, not a helper or Runtime Supervisor
process id.

### 3.3 Session Terminals

The Host Coordinator owns one host PTY master per interactive Client Session. The
PTY slave is attached to non-detached `runsc exec` standard streams with a guest
TTY. The root attached `runsc run` client remains terminal-neutral and is not the
Session PTY attachment path. Production must not depend on `runsc exec
-console-socket`.

Session terminal ownership is the Host Coordinator; a Client CLI never inherits
the sandbox Session PTY. For each Client Session the coordinator maintains the
session identity needed for routing and cleanup, including Session ID, PTY master,
`runsc exec` client process identity, and guest process or process-group identity.

Interactive terminal control requires:

- Window resize applied to the host PTY master and guest `SIGWINCH` delivered to
  the exact session process or process group through runsc.
- Client control events (for example interrupt) translated into runsc signal
  operations for that exact session process or process group; raw host PTY
  control characters alone are not a sufficient contract.
- Per-session exit status collected from the non-detached `runsc exec` client as
  the primary source.
- On session close, PTY master loss, or exec-client loss: deregister the session
  before further terminal or escalation traffic for that session, stop the guest
  session process or process group with generation-exact runsc operations, reap
  the exec client, and close the PTY.

Disconnected Client Sessions close rather than reattach to an unbounded scrollback
owned by the coordinator.

### 3.4 Filesystem and Git Model

The Agent Workspace is mounted read-write. Tracked paths and untracked paths that
are not ignored propagate in both directions. The Git index, `HEAD`, references,
and objects are shared with the host in real time. Lazaret does not create a
separate worktree or branch and does not promise that the host working tree
remains unchanged.

By default, paths matched by the repository's effective Git ignore rules are
redirected to Ignored Workspace State. Existing host content at those paths is not
exposed to the Agent Sandbox, and sandbox writes remain Domain-scoped and persist
across restarts. This prevents agent-modified dependency trees, virtual
environments, generated executables, caches, and other ignored artifacts from
later being executed by host tools. Trusted host configuration may disable this
behavior when fully bidirectional ignored paths are required.

Ignored-path isolation is defense in depth and does not replace the mandatory Git
Sentry protections below.

Lazaret applies narrow protective mounts over host integration files that must not
be modified by the agent:

- The host repository's `.git/config` is exposed read-only.
- The host repository's `.git/hooks` is hidden behind sandbox-local transient
  storage.
- Supported host editor configuration directories may be hidden behind
  sandbox-local transient storage.

These protections do not make the workspace immutable. Their purpose is to stop
the sandbox from writing the protected host Git configuration and default hook
directory while preserving normal Git operations and bidirectional source edits.

### 3.5 Persistent Sandbox State

The State Anchor preserves developer tooling and selected sandbox system paths for
one Domain. It combines a Lazaret-owned prepared lower from the selected base
image with a Domain-scoped writable upper directory.

#### Prepared lower

Preparation resolves the selected base image, applies layers with a supported
OCI-aware preparer, and materialises an immutable Lazaret-owned root filesystem
tree under the Storage Root. The tree carries a prepared-artifact ID and a source
image identity. Live container-engine image mounts are not a production State
Anchor lower. Archive export alone is not a complete preparation boundary;
container tooling may participate only as transport into Lazaret-owned
preparation. Ad hoc unsupported tar extractors are not a production preparer.

Prepared-artifact identity is independent of its storage pathname. Before State
Anchor mount, Host Coordinator durable state binds the Domain generation to the
prepared-artifact ID with a prepared-lower lease. Distinct generations sharing
an artifact hold separate leases; an engine mount refcount is not a lease.

Concurrent preparation of the same source may reuse a completed artifact or
publish a new prepared-artifact ID. An incomplete preparation is never a State
Anchor lower. Preparation, lease acquisition, and reclaim serialize so GC acts
only after the final lease is released. Recovery may reclaim an abandoned
preparation only from matching exact-owned durable intent; foreign or mismatched
trees remain untouched.

The prepared rootfs preserves OCI modes and is exposed only as a read-only State
Anchor lower. Lazaret enforces immutability through artifact ownership and
lifecycle rather than by rewriting image permission bits.

#### Durable generation document

Durable Domain state is an embedded store opened exclusively by the Host
Coordinator process that holds the Domain's exclusive lifecycle lock for write.
No other process opens the store for read or write: Client CLIs, the Runtime
Supervisor, recovery observers, and status tools obtain state only through Host
Coordinator IPC or by becoming the lock-holding Host Coordinator. Domain flock
serializes which process may be that exclusive opener. Store mutations use
atomic transactions; an interrupted write leaves the last successfully committed
document, never a half-applied generation decision.

Protocol durable decision vocabulary, multi-role intent, and mismatch refuse are
defined by the protocol model. The product store encodes that generation document
in typed tables under a schema/db version (unknown newer versions fail closed
until an explicit Host Coordinator migration), including generation identity,
minted runtime component IDs, and participant ownership material (for example
prepared-artifact ID, pid/start, mount identity, network readiness fingerprint).
Participant roles include at least those the model tracks, plus product modules
such as `git_routing`, `sessions`, and `publication` as they land. Deterministic
paths are lookup hints for physical recovery, not ownership proofs.

Files not represented in the upper layer follow the selected base image. Files,
directories, and whiteouts recorded in the upper layer remain authoritative when
the lower image changes. This permits installed tools to survive restarts while
allowing unmodified base-image content to follow the selected image.

Persistent state is sandbox state, not host configuration. It must not contain or
override Lazaret's host control plane.

### 3.6 Network Isolation

The Network Sidecar role is realized on the Runtime Supervisor-owned install
path: the Runtime Supervisor (or a packaging-equivalent installer still bound to
the same Network Sidecar ID) holds network-administration capability only for
install and attestation in the Domain enforcement network namespace. The Agent
Sandbox does not receive that capability and may join only that prepared
enforcement namespace, not the host network namespace. Production connectivity uses
`slirp4netns`. Installing policy by driving nftables through runsc into the guest
is not a production path. Protocol helper ownership, network readiness, and
publication gates follow the protocol model.

#### Derived policy and readiness encoding

The Host Coordinator derives the generation's derived network policy from trusted
host configuration. The Runtime Supervisor installs only that derived policy and
attests readiness by observing installed routes and helper readiness in the
enforcement namespace—not by process exit status alone. The product records a
network readiness fingerprint as the durable encoding of protocol network
readiness. Before publication, Lazaret verifies from the Agent Sandbox network
view (or an equivalent generation-bound probe on the same enforcement namespace)
that default-denied private destinations are unreachable and that required
permitted reachability, including selected DNS resolvers, works.

#### Default policy and deny representation

IPv4 destinations are permitted by default except for the RFC 1918 private
address ranges (`10.0.0.0/8`, `172.16.0.0/12`, `192.168.0.0/16`), which are denied
by default. Explicit, more-specific allow rules may grant access within those
ranges. Lazaret also installs the reachability needed for the Domain's selected
DNS resolvers. Other permitted and denied destination prefixes come from trusted
host configuration.

Default and configured deny prefixes are enforced with **loopback-unicast deny
routes** in the Domain enforcement network namespace (routes that direct matching
destinations to a loopback unicast address so packets are not forwarded). Linux
`blackhole` routes are not the production deny representation for this path.
Equal-prefix allow/deny conflicts must be rejected or resolved in favor of denial.

Normal Linux longest-prefix routing determines the most specific matching route.
IPv4 and IPv6 must either receive equivalent policy or an address family must be
disabled.

The topology and policy-installation sequence must ensure that all external Agent
Sandbox traffic traverses the configured enforcement path. Dynamic policy changes
are not a requirement unless the implementation can apply them without weakening
that property.

### 3.7 Host Escalation

The Escalation Client exchanges request and result records through the
Escalation Mailbox: regular files written by atomic rename beneath host-private,
Domain-scoped paths. Request and result paths may use different mount modes. The
mailbox is not an authentication boundary. The Host Coordinator owns the mailbox
for the published generation. Host-only CLI/coordinator control may use
host-private Unix sockets that are never mounted into the Agent Sandbox.

Auto-approved host commands are launched as an argument vector without a shell.
Trailing arguments require an explicit grant on the matched rule.

Escalation authentication, correlation, approval, execution, cancellation, result
delivery, and terminal routing are defined by the
[TLA+ application protocol model](protocol/Lazaret.tla).

### 3.8 State Inspection and Reset

The host CLI provides read-only discovery, inspection, structural verification,
and explicit reset operations for Domain State Anchors. These operations resolve
a Domain through trusted host metadata and never accept an arbitrary host
filesystem path as an upper-layer target.

Inspection reports metadata and overlay changes without printing file contents by
default. Structural verification requires an inactive Domain and exclusive
lifecycle ownership so its result is not invalidated by concurrent writes. A
reset may target one configured persistent container path or all State Anchors in
the Domain. It discards the selected upper-layer state so the next launch follows
the current prepared lower; it does not modify the prepared lower artifact, Agent
Workspace, Ignored Workspace State, or unselected State Anchors.

Reset is permitted only after Lazaret holds the Domain's exclusive lifecycle lock
and has established that no Client Session, Session Coordinator constitutive
process, sandbox, network helper, host process, or overlay mount is using the
selected state. Confirmation flags may suppress the human prompt but may not
bypass these safety conditions. Reset must be crash-consistent and must never
follow a symlink outside the Domain Root.

## 4. Requirements

### 4.1 Security Requirements

| ID | Requirement |
| :--- | :--- |
| **SR-1** | Agent processes shall execute in a rootless gVisor sandbox and shall not receive host root authority. |
| **SR-2** | Host configuration shall never be mounted into the Agent Sandbox or located beneath a host path mounted into it. |
| **SR-3** | Host paths outside the Agent Workspace, developer-configured volumes, and Lazaret-owned fixed control mounts shall not be accessible to the Agent Sandbox. |
| **SR-4** | The sandbox shall be unable to modify the host repository's `.git/config` or default `.git/hooks` directory through the workspace mount. |
| **SR-5** | Domain network policy shall be established before the Agent Sandbox starts. Network-administration capability for policy install shall be held only on the Runtime Supervisor-owned Network Sidecar install path; the Agent Sandbox shall not receive network-administration capability. |
| **SR-6** | Network policy shall cover every enabled address family and shall deny equal-specificity policy conflicts. Default and configured deny prefixes shall be enforced with loopback-unicast deny routes in the Domain enforcement network namespace; Linux blackhole routes shall not be the production deny representation. |
| **SR-7** | Host actions shall execute only under protocol-model approval (developer or auto-rule). |
| **SR-8** | Auto-approved host commands shall execute without a shell and shall permit trailing arguments only when the matched rule explicitly grants them. |
| **SR-9** | Protocol peer authentication and authorization shall follow the protocol model (role, Agent Profile, Domain ID, and runtime component ID binding). |
| **SR-10** | Domain sockets, mailboxes, and coordination files shall reside in a host-private directory owned by the developer. |
| **SR-11** | Runtime and persistent resources belonging to different Domain IDs shall remain isolated. |
| **SR-12** | The Agent Sandbox shall not join host user, PID, IPC, UTS, cgroup, or network namespaces; the only shared network namespace permitted is the Domain's Network Sidecar enforcement namespace prepared for that generation. |
| **SR-13** | Git-ignored Agent Workspace paths shall use Ignored Workspace State by default, preventing the sandbox from reading or modifying corresponding host content; only trusted host configuration may disable this behavior. |
| **SR-14** | State Anchor maintenance shall remain confined to the resolved Domain Root. Destructive maintenance shall require exclusive lifecycle ownership and an inactive, unmounted target. |
| **SR-15** | Lazaret shall not use a live container-engine image mount as the production State Anchor lower; the lower shall be a Lazaret-owned prepared lower bound by a prepared-lower lease. Archive export alone shall not be treated as a complete preparation boundary. |
| **SR-16** | Session control, registration, and Host Escalation shall authenticate the Session Coordinator ID on the Host Coordinator protocol face and shall not treat Runtime Supervisor or attached runsc process identifiers as substitute protocol peer identities. |
| **SR-17** | Network Sidecar ID in attachment authorization shall name the Network Sidecar role instance, not a connectivity-helper or Runtime Supervisor process identifier. |

### 4.2 Functional Requirements

| ID | Requirement |
| :--- | :--- |
| **FR-1** | Lazaret shall derive a stable Domain ID from the selected Agent Profile and canonical Agent Workspace. |
| **FR-2** | Concurrent Client Sessions in one Domain shall share one logical Session Coordinator, Agent Sandbox, Network Sidecar, and State Anchor for the published generation. |
| **FR-3** | Tracked and non-ignored workspace edits and supported Git operations shall propagate bidirectionally between host and sandbox. |
| **FR-4** | Selected sandbox paths and Ignored Workspace State shall persist across Domain restarts without copying Lazaret host configuration into the sandbox. |
| **FR-5** | Escalation prompt routing and Escalation Result delivery shall follow the protocol model on the Host Coordinator face. |
| **FR-6** | Teardown when no Client Sessions remain shall follow the protocol model; product teardown shall release the generation's physical resources. |
| **FR-7** | Product recovery shall not assume external runtime resources disappeared with their owner process and shall apply protocol intent/mismatch refuse rules to physical leftovers (exact-owned cleanup only). |
| **FR-8** | Lazaret shall support interactive terminal sessions without degrading supported host terminal capabilities. |
| **FR-9** | Trusted host configuration shall allow the developer to disable Git-ignored path isolation for an Agent Profile. |
| **FR-10** | Session registration and escalation identity binding shall follow the protocol model. |
| **FR-11** | The host CLI shall list, inspect, structurally verify, and reset all or selected State Anchors without requiring direct manipulation of Lazaret's storage layout. |
| **FR-12** | The logical Session Coordinator for a Domain generation shall be realized by exactly the Host Coordinator, Runtime Supervisor, and attached runsc client as constitutive processes. |
| **FR-13** | The Host Coordinator, Runtime Supervisor, and attached runsc process chain shall realize Session Coordinator presence and sandbox coupling for the protocol model, with product recovery limited to exact-owned physical leftovers. |
| **FR-14** | The Host Coordinator shall own one host PTY master per interactive Client Session; the PTY slave shall attach through non-detached `runsc exec` standard streams. The root attached `runsc run` client shall remain terminal-neutral. Production Session PTYs shall not depend on `runsc exec -console-socket`. |
| **FR-15** | For each interactive Client Session, Lazaret shall apply window resize to the host PTY master and deliver guest `SIGWINCH` to the exact session process or process group through runsc; translate Client control events into runsc signal operations for that process or process group; collect exit status primarily from the non-detached `runsc exec` client; and on session end deregister before further terminal or escalation traffic for that session, stop the guest session process or process group with generation-exact runsc operations, reap the exec client, and close the PTY. |
| **FR-16** | Domain network connectivity shall use `slirp4netns` as the production connectivity helper, with exact-owned process identity for recovery under the protocol helper ownership rules. |
| **FR-17** | The Domain durable store shall be opened for read or write only by the Host Coordinator process that holds the Domain exclusive lifecycle lock; no other process shall open the store file. Mutations shall apply as whole store transactions. Protocol durable intent is encoded in that store. |
| **FR-18** | Product network readiness encoding shall include a network readiness fingerprint and the pre-publication reachability verification described under network isolation; protocol publication and readiness gates follow the protocol model. |
| **FR-19** | The Host Coordinator shall derive generation-bound network policy from trusted host configuration; the Runtime Supervisor shall install only that derived policy and attest readiness by observed namespace state. Durable network participant state shall record the network readiness fingerprint. |
| **FR-20** | Before publication, Lazaret shall verify from the Agent Sandbox network view, or an equivalent generation-bound probe using the same enforcement namespace, that default-denied private destinations are unreachable and that required permitted reachability including selected DNS resolvers works. |
| **FR-21** | The durable generation document encoding shall include schema/db version, generation identity, minted runtime component IDs, model-governed durable decision and participant intent, and ownership material for product recovery. Unknown newer schema versions shall fail closed until an explicit Host Coordinator migration runs. |
| **FR-22** | Preparation shall use a supported OCI-aware preparer that materialises a Lazaret-owned immutable rootfs with source identity and prepared-artifact ID. A durable generation-bound prepared-lower lease shall exist before State Anchor mount. |

### 4.3 Developer-Experience Requirements

| ID | Requirement |
| :--- | :--- |
| **DX-1** | A developer shall be able to launch an Agent Profile in the current workspace with one command. |
| **DX-2** | Tools installed in configured persistent sandbox paths and dependencies stored in Ignored Workspace State shall remain available on later launches of the same Domain. |
| **DX-3** | Normal source editing, `git status`, staging, committing, and reference updates shall work from inside the Agent Sandbox. |
| **DX-4** | Escalation prompts shall identify the requesting profile, session, command, and justification without mixing terminal input or output between sessions. |
| **DX-5** | Failures shall report actionable diagnostics and shall not leave the developer's terminal in a corrupted mode. |
| **DX-6** | State inspection shall provide human-readable and machine-readable output without exposing persisted file contents by default, and reset shall show its resolved Domain and exact scope before confirmation. |

### 4.4 Operational Requirements

| ID | Requirement |
| :--- | :--- |
| **OR-1** | The Session Coordinator shall maintain exclusive runtime ownership of Domain generation resources. An exclusive Domain lock shall elect at most one Host Coordinator leader for cold start or recovery of a Domain; concurrent losers shall fail closed. |
| **OR-2** | Accepted protocol requests shall resolve per the protocol model. |
| **OR-3** | Cancellation and process termination shall follow the protocol model (no stranded host command, no permanent block of another Client Session). |
| **OR-4** | Security-sensitive behavior shall be covered by integration tests on supported runsc, filesystem, and network configurations. Test evidence belongs in the journal. |
| **OR-5** | An interrupted State Anchor reset shall recover to either the prior generation or a new empty generation; it shall not leave a partially reset active upper layer. |
| **OR-6** | Lazaret shall not require a persistent global daemon or multi-Domain resident process that holds mutable runtime authority across Domains. Per-Domain authority shall be scoped by Domain ID, generation, configuration fingerprint, role identity, and exact physical ownership. |
| **OR-7** | Product GC shall provide policy-controlled reclamation for prepared artifacts after all protocol leases for the prepared-artifact ID are released. Shared-artifact reclaim shall wait until no lease remains for that artifact. In-progress prepare trees and foreign trees shall not be deleted; exact-owned abandoned prepare trees may be reclaimed only through fail-closed recovery backed by durable prepare intent. |