Refresh daemon docs and mark web UI experimental

internal/daemon/doc.go and ARCHITECTURE.md were written before the
subpackage extractions and still referenced old structure (in-progress
phrasing, missing opstate/dmsnap/fcproc/imagemgr/session/workspace,
mentions of opRegistry by its old name). Both now describe the current
shape: composition root + six leaf subpackages, lock ordering rooted
at vmLocks[id], and the one intra-package dependency (workspace →
session for ShellQuote + FormatStepError).

README.md and AGENTS.md mark the local web UI as experimental. It is
still enabled by default at 127.0.0.1:7777, but the docs now state
plainly that its surface is not stable or hardened and not intended for
anything beyond single-user localhost use. AGENTS.md also points at
ARCHITECTURE.md for the subpackage layout.

No code changes; tests still green.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/daemon/doc.go

@@ -1,61 +1,87 @@
 // Package daemon hosts the Banger daemon process.
 //
 // The daemon exposes a JSON-RPC endpoint over a Unix socket and, optionally,
-// a local web UI. It owns VM lifecycle, image management, guest sessions,
-// host networking bootstrap, and state persistence via internal/store.
+// an experimental local web UI. It owns VM lifecycle, image management,
+// guest sessions, host networking bootstrap, and state persistence via
+// internal/store.
 //
-// The package is organised into cohesive groups. A phased refactor is
-// splitting each group into a subpackage; file names below reflect the
-// current (in-progress) grouping.
+// The package is organised into cohesive groups. Pure stateless helpers for
+// each group have been lifted into subpackages; orchestrator methods
+// (Daemon receivers) stay here and compose them.
 //
-// VM lifecycle:
+// Subpackages:
+//
+//	internal/daemon/opstate    Generic Registry[T AsyncOp] for async
+//	                           operations (VM create, image build).
+//	internal/daemon/dmsnap     Device-mapper COW snapshot lifecycle.
+//	internal/daemon/fcproc     Firecracker process helpers: bridge/tap,
+//	                           binary resolution, PID lookup, wait/kill.
+//	internal/daemon/imagemgr   Image subsystem helpers: path validation,
+//	                           artifact staging, guest provisioning script
+//	                           generator, metadata.
+//	internal/daemon/session    Guest-session helpers: state paths, runner
+//	                           / inspect / signal scripts, state snapshot
+//	                           parsing, launch helpers, ShellQuote,
+//	                           FormatStepError.
+//	internal/daemon/workspace  Workspace helpers: git repo inspection,
+//	                           shallow copy prep, guest-side import,
+//	                           finalize script generation.
+//
+// VM lifecycle (in this package):
 //
 //	vm_create.go      CreateVM and create-time disk provisioning
 //	vm_lifecycle.go   Start/Stop/Restart/Kill/Delete
 //	vm_set.go         SetVM mutation
 //	vm_stats.go       stats, health, ping, stale reaper
 //	vm_disk.go        system overlay, work disk provisioning
-//	vm_authsync.go    per-VM authorized_key, git identity, and auth file sync
-//	vm_create_ops.go  async begin/status/cancel registry for create
+//	vm_authsync.go    per-VM authorized_key, git identity, auth file sync
+//	vm_create_ops.go  async begin/status/cancel (uses opstate.Registry)
+//	vm_locks.go       vmLockSet: per-VM mutex set
+//	vm.go             fcproc forwarders, DNS helpers, small utilities
 //	capabilities.go   pluggable capability hooks executed at VM start
 //	preflight.go      prereq validation for VM start
-//	snapshot.go       device-mapper COW snapshot helpers
+//	snapshot.go       dmsnap forwarders + dmSnapshotHandles type alias
 //	ports.go          port forwarding inspection
 //
-// Image management:
+// Image management (in this package):
 //
 //	images.go             register, promote, delete, find, list
-//	imagebuild.go         build via firecracker build VM
-//	image_build_ops.go    async begin/status/cancel registry for build
-//	image_seed.go         managed work-seed fingerprint refresh
+//	imagebuild.go         orchestrates the transient firecracker build VM
+//	image_build_ops.go    async begin/status/cancel (uses opstate.Registry)
+//	image_seed.go         managed work-seed SSH fingerprint refresh
 //
-// Guest interaction:
+// Guest interaction (in this package):
 //
-//	guest_sessions.go    long-lived guest commands, attach, logs
-//	ssh_client_config.go daemon-managed SSH client key material
-//	workspace.go         materialising host repos into guest
-//	opencode.go          opencode host-side helpers
+//	guest_sessions.go      dialGuest, waitForGuestSSH, refresh/inspect
+//	session_lifecycle.go   Start/Stop/Kill/Get/List/signal orchestrators
+//	session_attach.go      BeginGuestSessionAttach + bridge/forward/watch
+//	session_stream.go      GuestSessionLogs, SendToGuestSession
+//	session_controller.go  guestSessionController, sessionRegistry
+//	ssh_client_config.go   daemon-managed SSH client key material
+//	workspace.go           ExportVMWorkspace, PrepareVMWorkspace
+//	opencode.go            opencode host-side helpers
 //
-// Host bootstrap:
+// Host bootstrap (in this package):
 //
 //	nat.go           NAT prereq registration
 //	dns_routing.go   systemd-resolved per-interface routing
-//	tap_pool.go      TAP interface pool
+//	tap_pool.go      TAP interface pool (state in tapPool type)
 //
-// Core:
+// Core (in this package):
 //
 //	daemon.go         Daemon struct, Open/Close/Serve, dispatch
 //	dashboard.go      dashboard metrics aggregation
 //	doctor.go         host diagnostics
 //	logger.go         slog configuration
 //	runtime_assets.go paths to bundled companion binaries
-//	web.go            embedded web UI server
+//	web.go            experimental local web UI server
 //
 // Lock ordering:
 //
 //	vmLocks[id]  →  {createVMMu, imageOpsMu}  →  subsystem-local locks
 //
-// Subsystem-local locks live on the owning type (tapPool.mu,
-// sessionRegistry.mu, opRegistry.mu, guestSessionController.attachMu/writeMu)
-// and do not contend with each other. See ARCHITECTURE.md for details.
+// Subsystem-local locks live on their owning type (tapPool.mu,
+// sessionRegistry.mu, opstate.Registry mu, guestSessionController.attachMu /
+// writeMu) and do not contend with each other. See ARCHITECTURE.md for
+// details.
 package daemon