docs: Campaign LA — pinned launch-contract schema COMMITTED into plan LA1

The LA3 Opus review process note was right: the contract both sides
implement lived only in orchestrator prompts, which is exactly the drift
mode the pin exists to prevent (and it produced the paths-key CRITICAL).
The schema, field rules, probe-mode discriminator, and status vocabulary
are now a binding plan section; amendments change this text first,
implementations second. Ledger: LA3 fix round dispatched.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/AcDream.Headless/Hosting/HeadlessSessionHost.cs

@@ -113,6 +113,19 @@ internal sealed class HeadlessSessionHost : IDisposable
     private readonly HeadlessCredentialSecret _credential;
     private readonly HeadlessDiagnosticWriter _diagnostics;
     /// <summary>
+    /// Campaign LA slice LA1: a SEPARATE per-session sink from
+    /// <see cref="_diagnostics"/> — a no-op instance when
+    /// <see cref="HeadlessSessionDescriptor.StatusFile"/> was not configured.
+    /// See <see cref="SessionStatusWriter"/>'s own doc for why this is not a
+    /// rework of the shared-stdout diagnostics writer.
+    /// </summary>
+    private readonly SessionStatusWriter _statusWriter;
+    /// <summary>Guards <see cref="Stop"/>'s <c>disconnected</c> status event
+    /// so a Stop() on a session that never actually reached Connected (e.g.
+    /// disposing a fresh, never-started host) does not report a spurious
+    /// disconnect.</summary>
+    private bool _hasConnected;
+    /// <summary>
     /// Campaign OP slice OP7 (2026-08-11), D8: the parsed
     /// <c>characterOptions</c> block — empty when the config omitted it.
     /// Parsed once at construction; <see cref="HeadlessConfigurationLoader"/>
@@ -271,6 +284,10 @@ internal sealed class HeadlessSessionHost : IDisposable
             var commands = new DirectGameRuntimeCommandAdapter(
                 runtime,
                 bridge);
+            // Campaign LA slice LA1: no-op instance when
+            // descriptor.StatusFile is unset — every call site below stays
+            // unconditional.
+            var statusWriter = new SessionStatusWriter(descriptor.StatusFile);
             var liveSession = new LiveSessionHost(
                 runtime.Session,
                 new LiveSessionHostBindings(
@@ -318,14 +335,25 @@ internal sealed class HeadlessSessionHost : IDisposable
                             descriptor.Id,
                             $"connecting:{host}:{port}:{user}",
                             runtime.Generation.Value),
-                    () => diagnostics.Message(
+                    () =>
+                    {
+                        diagnostics.Message(
+                            descriptor.Id,
+                            "connected",
+                            runtime.Generation.Value);
+                        statusWriter.Connected(descriptor.Id);
+                        _hasConnected = true;
+                    },
+                    roster => statusWriter.CharacterList(descriptor.Id, roster),
+                    selection => statusWriter.EnteredWorld(
                         descriptor.Id,
-                        "connected",
-                        runtime.Generation.Value)));
+                        selection.CharacterId,
+                        selection.CharacterName)));
 
             Runtime = runtime;
             Commands = commands;
             _liveSession = liveSession;
+            _statusWriter = statusWriter;
             _localPlayerFrame =
                 runtime.CreateLocalPlayerFrameController(
                     new HeadlessLocalPlayerFrameHost(
@@ -421,8 +449,13 @@ internal sealed class HeadlessSessionHost : IDisposable
         _pendingConfirmation = null;
     }
 
-    internal RuntimeSessionStartResult Start() =>
-        Commands.Session.Start(Runtime.Generation);
+    internal RuntimeSessionStartResult Start()
+    {
+        // Campaign LA slice LA1: "started" = session host start — the
+        // earliest point this session actually attempts to connect.
+        _statusWriter.Started(_descriptor.Id);
+        return Commands.Session.Start(Runtime.Generation);
+    }
 
     internal RuntimeSessionStartResult Reconnect() =>
         Commands.Session.Reconnect(Runtime.Generation);
@@ -470,6 +503,15 @@ internal sealed class HeadlessSessionHost : IDisposable
         // (possibly disposed) WorldSession in the window between this Stop
         // and the next CreateEventRoute call.
         _currentSession = null;
+        // Campaign LA slice LA1: only report a disconnect for a session that
+        // actually reached Connected — a Stop() on a never-started or
+        // never-connected host (e.g. immediate Dispose()) is not a real
+        // disconnect.
+        if (_hasConnected)
+        {
+            _hasConnected = false;
+            _statusWriter.Disconnected(_descriptor.Id, "stopped");
+        }
         return result;
     }
 
@@ -592,6 +634,13 @@ internal sealed class HeadlessSessionHost : IDisposable
                         _descriptor.Id,
                         "disposed",
                         _stoppedGeneration);
+                    // Campaign LA slice LA1: "exited" = terminal — the sole
+                    // point every disposal path (graceful and post-
+                    // quarantine) converges on.
+                    _statusWriter.Exited(
+                        _descriptor.Id,
+                        _faulted ? 1 : 0,
+                        _faulted ? "fault" : "disposed");
                     _disposeStage++;
                     _disposed = true;
                     break;