feat(domain,infra,app): rotation/rétention log.jsonl + lecture paginée (LS6)

Backend uniquement (UI React repoussée à LS7) :
- domain : port ConversationArchive + structs SegmentStats/PageCursor/PageDirection/
  TurnSlice/RotationDecision/RotationThresholds, fn pures rotation_plan/clamp_page_limit
  + consts ; re-exports lib.
- infrastructure : impl ConversationArchive pour FsConversationLog (stats/rotate/page
  + helpers), archive segmentée hors chemin chaud.
- application : ReadConversationPage + DTO + ConversationArchiveProvider (conversation/paginate),
  RotateConversationLog (conversation/rotate), exports mod/lib.
- app-tauri : AppConversationArchiveProvider + wiring (state), rotation détachée dans
  launch_agent + commande read_conversation_page (commands), DTOs (dto),
  commande enregistrée (generate_handler!).
- tests (QA, verts) : conversation_log, conversation_rotate_paginate (nouveau),
  dto (module test). Pivots INV-LS6 et cohérence fold-après-rotation verts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/app-tauri/src/commands.rs

@@ -17,12 +17,13 @@ use application::{
     GitInitInput, GitLogInput, GitStagePathInput, GitStatusInput, InspectConversationInput,
     LaunchAgentInput, ListAgentsInput, ListLayoutsInput, ListMemoriesInput,
     ListResumableAgentsInput, ListSkillsInput, LiveSessions, LoadLayoutInput, McpRuntime,
-    MutateLayoutInput, OpenProjectInput, ReadAgentContextInput, ReadMemoryIndexInput,
-    ReadProjectContextInput, RecallMemoryInput, ReconcileLayoutsInput, RenameLayoutInput,
-    ResolveAgentPermissionsInput, ResolveMemoryLinksInput, SetActiveLayoutInput,
-    SnapshotRunningAgentsInput, StopLiveAgentInput, SyncAgentWithTemplateInput,
-    UnassignSkillFromAgentInput, UpdateAgentContextInput, UpdateAgentPermissionsInput,
-    UpdateMemoryInput, UpdateProjectContextInput, UpdateProjectPermissionsInput, UpdateSkillInput,
+    MutateLayoutInput, OpenProjectInput, ReadAgentContextInput, ReadConversationPageInput,
+    ReadMemoryIndexInput, ReadProjectContextInput, RecallMemoryInput, ReconcileLayoutsInput,
+    RenameLayoutInput, ResolveAgentPermissionsInput, ResolveMemoryLinksInput,
+    RotateConversationLogInput, SetActiveLayoutInput, SnapshotRunningAgentsInput,
+    StopLiveAgentInput, SyncAgentWithTemplateInput, UnassignSkillFromAgentInput,
+    UpdateAgentContextInput, UpdateAgentPermissionsInput, UpdateMemoryInput,
+    UpdateProjectContextInput, UpdateProjectPermissionsInput, UpdateSkillInput,
 };
 use domain::ports::PtyHandle;
 
@@ -43,13 +44,14 @@ use crate::dto::{
     InterruptAgentRequestDto, LaunchAgentRequestDto, LayoutDto, LayoutOperationDto, ListLayoutsDto,
     LiveAgentListDto, MemoryDto, MemoryIndexDto, MemoryLinksDto, MemoryListDto,
     OpenTerminalRequestDto, ProfileDto, ProfileListDto, ProjectDto, ProjectListDto,
-    ProjectPermissionsDto, ProjectWorkStateDto, ReadAgentContextResponseDto, ReattachChatDto,
-    ReattachResultDto, RecallMemoryRequestDto, RenameLayoutRequestDto, ReplyChunk,
-    ResizeTerminalRequestDto, ResolveAgentPermissionsRequestDto, ResumableAgentListDto,
-    SaveEmbedderProfileRequestDto, SaveProfileRequestDto, SetActiveLayoutRequestDto, SkillDto,
-    SkillListDto, StopLiveAgentRequestDto, StopLiveAgentResponseDto,
-    SyncAgentWithTemplateRequestDto, SyncResultDto, TemplateDto, TemplateListDto,
-    TerminalClosedDto, TerminalSessionDto, UnassignSkillRequestDto, UpdateAgentContextRequestDto,
+    ProjectPermissionsDto, ProjectWorkStateDto, ReadAgentContextResponseDto,
+    ReadConversationPageRequestDto, ReattachChatDto, ReattachResultDto, RecallMemoryRequestDto,
+    RenameLayoutRequestDto, ReplyChunk, ResizeTerminalRequestDto,
+    ResolveAgentPermissionsRequestDto, ResumableAgentListDto, SaveEmbedderProfileRequestDto,
+    SaveProfileRequestDto, SetActiveLayoutRequestDto, SkillDto, SkillListDto,
+    StopLiveAgentRequestDto, StopLiveAgentResponseDto, SyncAgentWithTemplateRequestDto,
+    SyncResultDto, TemplateDto, TemplateListDto, TerminalClosedDto, TerminalSessionDto,
+    TurnPageDto, UnassignSkillRequestDto, UpdateAgentContextRequestDto,
     UpdateAgentPermissionsRequestDto, UpdateMemoryRequestDto, UpdateProjectContextRequestDto,
     UpdateProjectPermissionsRequestDto, UpdateSkillRequestDto, UpdateTemplateRequestDto,
     WriteTerminalRequestDto,
@@ -989,6 +991,39 @@ pub async fn get_project_work_state(
         .map_err(ErrorDto::from)
 }
 
+/// `read_conversation_page` — human, paginated read of a conversation's **full**
+/// transcript (lot LS6). Archive-aware (segments + active), text never truncated.
+///
+/// # Errors
+/// Returns an [`ErrorDto`] (`INVALID` for a malformed project/conversation id,
+/// `NOT_FOUND` if the project is unknown, `STORE` on log I/O failure).
+#[tauri::command]
+pub async fn read_conversation_page(
+    request: ReadConversationPageRequestDto,
+    state: State<'_, AppState>,
+) -> Result<TurnPageDto, ErrorDto> {
+    let project = resolve_project(&request.project_id, &state).await?;
+    let conversation = uuid::Uuid::parse_str(&request.conversation_id)
+        .map(domain::ConversationId::from_uuid)
+        .map_err(|_| ErrorDto {
+            code: "INVALID".to_owned(),
+            message: format!("invalid conversation id: {}", request.conversation_id),
+        })?;
+    let cursor = request.cursor();
+    let limit = request.limit.unwrap_or(0);
+    state
+        .read_conversation_page
+        .execute(ReadConversationPageInput {
+            project_root: project.root,
+            conversation,
+            cursor,
+            limit,
+        })
+        .await
+        .map(TurnPageDto::from)
+        .map_err(ErrorDto::from)
+}
+
 /// `list_live_agents` — list every agent that currently owns a live session
 /// (raw PTY **or** structured/chat) and the cell hosting each, so the UI can
 /// disable an agent already running in another cell (the "one live session per
@@ -1222,6 +1257,9 @@ pub async fn launch_agent(
     // agent so an auto-resume (which only carries agent/node/conversation) can recompose a
     // full `LaunchAgentInput`. Cloned here — `project` is moved into the launch below.
     let resume_project = project.clone();
+    // Lot LS6 — project root captured before `project` moves, for the off-hot-path log
+    // rotation triggered at thread (re)open below.
+    let rotation_root = project.root.clone();
 
     let output = state
         .launch_agent
@@ -1250,6 +1288,28 @@ pub async fn launch_agent(
         );
     }
 
+    // Lot LS6 — rotation **best-effort** du log, déclenchée à la (re)ouverture du fil et
+    // **hors chemin chaud** : détachée (`tokio::spawn`) pour n'ajouter aucune latence au
+    // launch, erreurs **avalées** (la rotation ne doit jamais casser une reprise). Un
+    // `append` ne déclenche JAMAIS la rotation. Skippée si la cellule ne porte pas une
+    // `conversation_id` UUID (rien à roter).
+    if let Some(conversation) = request
+        .conversation_id
+        .as_deref()
+        .and_then(|raw| uuid::Uuid::parse_str(raw).ok())
+        .map(domain::ConversationId::from_uuid)
+    {
+        let rotate = std::sync::Arc::clone(&state.rotate_conversation_log);
+        tokio::spawn(async move {
+            let _ = rotate
+                .execute(RotateConversationLogInput {
+                    project_root: rotation_root,
+                    conversation,
+                })
+                .await;
+        });
+    }
+
     let session_id = output.session.id;
     // Host cell of the freshly (re)launched session — the pivot the level-2 tap reports
     // to the service alongside the agent.