feat(my-deepagent): v0.3 PR #1 — interactive session persistence + LangGraph saver wiring

v0.3의 토대. REPL/GUI 둘 다 장기 대화를 영속해서 `mydeepagent --session <id>`
또는 `GET /api/sessions/{id}`로 어디서든 이어 진행 가능. Claude Code의
`claude --resume` 등가 능력.

Data model
- `persistence/models.py`:
  - 신규 `MessageRow` 테이블 — (session_id, seq) UNIQUE, role/content/
    tool_calls/token_count/is_summary/archived/ts. LangGraph checkpoint =
    source of truth, 이 테이블은 GUI/CLI 빠른 조회 mirror. divergence
    rebuild 매커니즘 없음 (단순성 우선).
  - `InteractiveSessionRow` 컬럼 8개 추가:
      total_input_tokens, total_output_tokens (PR #2 tiktoken으로 정밀화 예정),
      model, project_key (sha256(realpath(repo_path))[:16]),
      title (첫 user msg 50자), plan_mode (PR #5), parent_session_id (PR #6),
      depth (PR #6 sub-agent depth ≤ 3).
- `alembic/versions/684e70f4536a_*.py` (신규):
  - `op.batch_alter_table` 사용 — SQLite ALTER constraint 미지원 우회. Postgres는
    native DDL.
  - 자동생성이 제안한 LangGraph 테이블 (`checkpoints` 등) drop 라인은 의도적으로
    제거 (langgraph-checkpoint-postgres가 자체 관리).
  - server_default 박아서 기존 row 안전.

CLI
- `cli/interactive.py`:
  - REPL 진입 시 `get_checkpointer_ctx(config.database_url)` 컨텍스트 열고
    REPL 전체 동안 유지. `build_agent(..., checkpointer=saver)`로 deepagents에
    LangGraph saver wire. v0.2 PR #10의 CostMiddleware / AuditToolMiddleware
    보존.
  - `_invoke_and_stream`이 ainvoke 전후 명시적 MessageRow insert
    (user → ainvoke → assistant). last_message_at + total_*_tokens 누적 +
    첫 user msg로 title 자동 setter.
  - `InteractiveSession.thread_suffix` 도입. /model / /agent / /clear 호출
    시 suffix bump → LangGraph thread_id = `{session_id}:{suffix}` 로 새
    deepagents 컨텍스트 시작 (compaction과 같은 패턴, PR #2 재사용).
  - 신규 `--session <id|prefix>` 옵션: 기존 row 로드 (ended이면 거부) 또는
    신규 row insert (AgentPersonaRow upsert + project_key 박음).
  - `/clear` 슬래시 갱신: messages.archived=True + 새 thread 시작. 세션 자체
    는 살아있음 — `sessions show <id> --all`로 조회 가능.
- `cli/sessions.py` (신규): `mydeepagent sessions list/show/resume/end`.
  show <id> [--all]이 archived 메시지까지. 6+ char prefix + 중복 시 명시
  에러.
- `cli/main.py`: --session 옵션 + sessions 서브명령 + interactive_command
  시그니처 확장.

HTTP API
- `api/models.py`: SessionSummary / MessageInfo / SessionDetail /
  CreateSessionRequest / PostMessageRequest / SessionAck DTO 신규 (모두
  extra="forbid").
- `api/routes/sessions.py` (신규):
    GET  /api/sessions?limit=&state=
    GET  /api/sessions/{id}?all=true     (마지막 200 메시지)
    POST /api/sessions                    (persona_name, model_override, repo_path)
    POST /api/sessions/{id}/messages      (사용자 메시지 append, 동기 persist;
                                            PR #7 GUI에서 background ainvoke 추가)
    GET  /api/sessions/{id}/stream        (SSE — 0.5s polling, last-event-id 헤더
                                            + ?last_seq 둘 다 지원)
    POST /api/sessions/{id}/end
- `api/app.py`: sessions 라우터 마운트.

Tests
- `tests/integration/test_session_persist.py` (5 시나리오):
    1. create + post → row + 메시지 + title + token 누적 영속
    2. list가 신규 3 세션 모두 포함
    3. prefix resolution + 404
    4. end 후 메시지 거부 (409)
    5. ?all=true가 archived 메시지 surfacing

Gates
- ruff check + ruff format + mypy --strict: PASS (124 source files)
- pytest non-E2E: 608 PASS (25.86 s) — v0.2 PR #3 후 603에서 +5 신규
- pytest E2E real OpenRouter on Postgres: PASS 82.07 s (베이스라인 60–122s
  범위 내; DR-3 +20% 임계점 통과)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

my-deepagent/src/my_deepagent/persistence/models.py

@@ -345,7 +345,17 @@ class ArtifactRow(Base):
 
 
 class InteractiveSessionRow(Base):
-    """Interactive (non-run) agent sessions."""
+    """Interactive (non-run) agent sessions.
+
+    v0.3 PR #1 adds 8 columns supporting long-lived conversation persistence:
+    - `total_input_tokens` / `total_output_tokens` — tiktoken-estimated, OpenRouter
+      `usage_metadata` is unreliable on some forwarded responses (v0.1 known limit).
+    - `model` — active model id, updated by `/model` slash.
+    - `project_key` — `sha256(realpath(repo_path))[:16]` for memory/skills lookup.
+    - `title` — first user message truncated, shown in sessions list.
+    - `plan_mode` — PR #5 will toggle.
+    - `parent_session_id` / `depth` — PR #6 sub-agent linkage.
+    """
 
     __tablename__ = "interactive_sessions"
 
@@ -362,10 +372,70 @@ class InteractiveSessionRow(Base):
     last_message_at: Mapped[str | None] = mapped_column(Text, nullable=True)
     state: Mapped[str] = mapped_column(Text, nullable=False)
 
+    # v0.3 PR #1 additions ----------------------------------------------------
+    total_input_tokens: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
+    total_output_tokens: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
+    model: Mapped[str | None] = mapped_column(Text, nullable=True)
+    project_key: Mapped[str | None] = mapped_column(Text, nullable=True)
+    title: Mapped[str | None] = mapped_column(Text, nullable=True)
+    plan_mode: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    # ondelete=CASCADE on self FK so sub-agent rows are wiped if parent is deleted.
+    # nullable: root sessions have no parent.
+    parent_session_id: Mapped[str | None] = mapped_column(
+        String(36),
+        ForeignKey("interactive_sessions.id", ondelete="CASCADE"),
+        nullable=True,
+    )
+    depth: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
+
     def __repr__(self) -> str:
         return f"<InteractiveSessionRow id={self.id!r} state={self.state!r}>"
 
 
+# ---------------------------------------------------------------------------
+# messages — per-session conversation history (mirror of LangGraph checkpoint,
+# source of truth = LangGraph; this table is for fast GUI/CLI listing).
+# ---------------------------------------------------------------------------
+
+
+class MessageRow(Base):
+    """One row per user/assistant/system/tool message in an interactive session.
+
+    LangGraph's `checkpoints` table is the source of truth for deepagents state;
+    this table is a view-friendly mirror for `mydeepagent sessions show` /
+    `GET /api/sessions/{id}` etc. Divergence is not assumed — every `ainvoke`
+    around explicit insert keeps them in sync without a rebuild mechanism.
+    """
+
+    __tablename__ = "messages"
+    __table_args__ = (
+        UniqueConstraint("session_id", "seq", name="uq_messages_session_seq"),
+        Index("messages_session_seq_idx", "session_id", "seq"),
+    )
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
+    session_id: Mapped[str] = mapped_column(
+        String(36),
+        ForeignKey("interactive_sessions.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    seq: Mapped[int] = mapped_column(Integer, nullable=False)
+    role: Mapped[str] = mapped_column(Text, nullable=False)  # user|assistant|system|tool
+    content: Mapped[str] = mapped_column(Text, nullable=False)
+    tool_calls: Mapped[dict[str, Any] | None] = mapped_column(JSON, nullable=True)
+    token_count: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
+    # PR #2 compaction flags. PR #1 introduces the columns; PR #2 starts using them.
+    is_summary: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    archived: Mapped[bool] = mapped_column(Boolean, nullable=False, default=False)
+    ts: Mapped[str] = mapped_column(Text, nullable=False)
+
+    def __repr__(self) -> str:
+        return (
+            f"<MessageRow id={self.id!r} session={self.session_id[:8]} "
+            f"seq={self.seq} role={self.role!r}>"
+        )
+
+
 # ---------------------------------------------------------------------------
 # tool_calls
 # ---------------------------------------------------------------------------