wip: Campaign LA LA1 fix round — INCOMPLETE, stopped mid-task

Agent was stopped for token budget partway through the LA1 review fix
round. Landed here: F1 best-effort SessionStatusWriter, F2 App reader
tolerance (paths/mode), F5 argument-parsing hardening, plus new tests.
NOT DONE: F4 shared-fixture production shape (was the next step), F3
reconnect disconnected edge + recorded limitation, F6 exited
idempotency/reasons, F7 structural redaction test, F8 platform-guard
test + comment fix, optional RuntimeOptions PrintMembers redaction.

Build/test state UNVERIFIED at this commit. Next session: finish the
remaining findings, run the suites, then narrow re-review.

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

src/AcDream.App/Configuration/SessionConfiguration.cs

@@ -42,6 +42,26 @@ internal sealed class SessionConfiguration
 internal sealed class SessionProcessSettings
 {
     public SessionContentDescriptor? Content { get; init; }
+
+    /// <summary>Campaign LA slice LA1 review fix (F2): accepted so the SAME
+    /// document also satisfies the Headless loader's own
+    /// <c>process.paths</c> member (<c>HeadlessPathOverrides</c>) — parsed
+    /// and ignored here, exactly like <see cref="SessionDescriptor.Policy"/>
+    /// and <see cref="SessionDescriptor.CharacterOptions"/> below. App has
+    /// no config/data/cache directory override concept of its own (those
+    /// come from <c>ApplicationPathSet</c>/env vars on this host); only the
+    /// Headless host consumes overrides composed under this key.</summary>
+    public SessionProcessPathOverrides? Paths { get; init; }
+}
+
+/// <summary>Accepted-but-ignored mirror of Headless's
+/// <c>HeadlessPathOverrides</c> shape — see
+/// <see cref="SessionProcessSettings.Paths"/>.</summary>
+internal sealed class SessionProcessPathOverrides
+{
+    public string? ConfigDirectory { get; init; }
+    public string? DataDirectory { get; init; }
+    public string? CacheDirectory { get; init; }
 }
 
 internal sealed class SessionContentDescriptor
@@ -75,6 +95,19 @@ internal sealed record SessionDescriptor
     /// App has no bot-policy concept.</summary>
     public SessionPolicyDescriptor? Policy { get; init; }
 
+    /// <summary>Campaign LA slice LA1 review fix (F2): pinned-contract
+    /// mode discriminator. ABSENT means today's ONLY App behavior — an
+    /// ordinary play session — so every document written before this field
+    /// existed keeps parsing unchanged. <c>"probe"</c> (LA2's connect
+    /// ▸ characterList ▸ graceful-disconnect flow, no EnterWorld) is
+    /// HEADLESS-ONLY; the App loader rejects it with an explicit message
+    /// naming the field rather than the caller ever seeing a raw unmapped-
+    /// member <see cref="System.Text.Json.JsonException"/>. Any other value
+    /// is a configuration error — the pinned contract defines no other
+    /// mode literal, so a document is either silent about mode (play) or
+    /// says "probe" exactly.</summary>
+    public string? Mode { get; init; }
+
     [JsonRequired]
     public SessionCredentialDescriptor Credential { get; init; } = new();