feat: durable background execution + HITL suspend/resume schema

.agents/skills/frontend-testing/SKILL.md

@@ -33,7 +33,7 @@ Activate this skill when:
 - **Path alias**: `@/` maps to `<rootDir>/src/`
 - **Test match patterns**: `src/**/__tests__/**/*.{test,spec}.{ts,tsx}` and `src/**/*.{test,spec}.{ts,tsx}`
 - **Transform**: Custom `transform-import-meta.js` handles `import.meta` for Jest compatibility
-- **Global mocks** (in `jest.setup.js`): `@radix-ui/react-form`, `react-markdown`, `lucide-react/dynamicIconImports`, `@/components/common/genericIconComponent`, `@/icons/BotMessageSquare`, `@/stores/darkStore`, `localStorage`, `sessionStorage`, `crypto`
+- **Global mocks** (in `jest.setup.js`): `@radix-ui/react-form`, `react-markdown`, `remark-gfm`, `remark-math`, `rehype-mathjax/browser`, `lucide-react/dynamicIconImports`, `@/components/common/genericIconComponent`, `@/icons/BotMessageSquare`, `@/stores/darkStore`, `localStorage`, `sessionStorage`, `crypto`
 
 ## Key Commands
 

.agents/skills/frontend-testing/references/mocking.md

@@ -21,6 +21,7 @@ These modules are already mocked in `jest.setup.js`. Do NOT re-mock them unless
 
 - `@radix-ui/react-form` (all exports render children)
 - `react-markdown` (renders null)
+- `remark-gfm`, `remark-math`, `rehype-mathjax/browser` (no-op plugins; pure ESM that fails to parse under jest)
 - `lucide-react/dynamicIconImports` (empty object)
 - `@/components/common/genericIconComponent` (renders null)
 - `@/icons/BotMessageSquare` (renders null)

docs/docs/Components/run-flow.mdx

@@ -14,6 +14,10 @@ When used with an agent, the `name` and `description` metadata that the agent us
 
 When you select a flow for the **Run Flow** component, it uses the target flow's graph structure to dynamically generate input and output fields on the **Run Flow** component.
 
+:::warning
+The target flow cannot use Human-in-the-Loop: a flow containing a connected **Human Input** node, or an agent tool that requires approval, is rejected with an error because a nested run cannot pause for a decision. Place the approval step in the parent flow instead.
+:::
+
 ## Run Flow parameters
 
 <PartialParams />

src/backend/base/langflow/alembic/versions/5e6d61582763_merge_message_user_id_and_hitl_heads.py

@@ -0,0 +1,25 @@
+"""merge message user id and hitl heads
+
+Revision ID: 5e6d61582763
+Revises: 47aca8c17d23, 9cbe2f682e12
+Create Date: 2026-07-13 17:00:00.000000
+
+Phase: EXPAND
+
+"""
+
+from collections.abc import Sequence
+
+# revision identifiers, used by Alembic.
+revision: str = "5e6d61582763"  # pragma: allowlist secret
+down_revision: str | None = ("47aca8c17d23", "9cbe2f682e12")  # pragma: allowlist secret
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    pass
+
+
+def downgrade() -> None:
+    pass

src/backend/base/langflow/alembic/versions/9cbe2f682e12_merge_hitl_checkpoints_and_release_heads.py

@@ -0,0 +1,25 @@
+"""merge hitl checkpoints and release heads
+
+Phase: EXPAND (no DDL - merge point only)
+
+Revision ID: 9cbe2f682e12
+Revises: 9d5e24d777bf, a1f4c9d27b30
+Create Date: 2026-07-13 10:43:02.800991
+
+"""
+
+from collections.abc import Sequence
+
+# revision identifiers, used by Alembic.
+revision: str = "9cbe2f682e12"
+down_revision: str | None = ("9d5e24d777bf", "a1f4c9d27b30")
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    pass
+
+
+def downgrade() -> None:
+    pass

src/backend/base/langflow/alembic/versions/a1f4c9d27b30_add_job_checkpoints_table.py

@@ -0,0 +1,52 @@
+"""add job_checkpoints table for durable suspend/resume checkpoints.
+
+Stores one opaque, already-serialized checkpoint blob per (job_id, kind): the
+graph producer writes JSON, the agent saver (LE-1447) writes base64(msgpack).
+UNIQUE(job_id, kind) keeps a single live checkpoint per kind.
+
+Revision ID: a1f4c9d27b30
+Revises: c7412b389256
+Create Date: 2026-06-15 09:00:00.000000
+
+Phase: EXPAND
+"""
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "a1f4c9d27b30"  # pragma: allowlist secret
+down_revision: str | None = "c7412b389256"  # pragma: allowlist secret
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    from langflow.utils import migration
+
+    conn = op.get_bind()
+    if not migration.table_exists("job_checkpoints", conn):
+        op.create_table(
+            "job_checkpoints",
+            sa.Column("id", sa.Uuid(), nullable=False),
+            sa.Column("job_id", sa.Uuid(), nullable=False),
+            sa.Column("kind", sa.String(), nullable=False),
+            sa.Column("blob", sa.Text(), nullable=False),
+            sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
+            sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
+            sa.PrimaryKeyConstraint("id"),
+            sa.UniqueConstraint("job_id", "kind", name="uq_job_checkpoints_job_id_kind"),
+        )
+        with op.batch_alter_table("job_checkpoints", schema=None) as batch_op:
+            # No index on ``id``: the PRIMARY KEY already provides a unique index, so a separate
+            # ix_job_checkpoints_id would be dead duplicate DDL.
+            batch_op.create_index(batch_op.f("ix_job_checkpoints_job_id"), ["job_id"], unique=False)
+
+
+def downgrade() -> None:
+    from langflow.utils import migration
+
+    conn = op.get_bind()
+    if migration.table_exists("job_checkpoints", conn):
+        op.drop_table("job_checkpoints")

src/backend/base/langflow/alembic/versions/c7412b389256_hitl_suspended_status_and_pause_resume_.py

@@ -0,0 +1,50 @@
+"""hitl suspended status and pause resume signals.
+
+Adds JobStatus.SUSPENDED to job_status_enum and SignalType.PAUSE/RESUME to
+execution_signal_type_enum so a run can suspend for human input and resume.
+
+Revision ID: c7412b389256
+Revises: 8ce44e4858c6
+Create Date: 2026-06-09 16:19:43.372632
+
+Phase: EXPAND
+"""
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "c7412b389256"  # pragma: allowlist secret
+down_revision: str | None = "8ce44e4858c6"  # pragma: allowlist secret
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+_OLD_SIGNAL_ENUM = sa.Enum("stop", name="execution_signal_type_enum")
+_NEW_SIGNAL_ENUM = sa.Enum("stop", "pause", "resume", name="execution_signal_type_enum")
+
+
+def upgrade() -> None:
+    bind = op.get_bind()
+    if bind.dialect.name == "postgresql":
+        # ALTER TYPE ... ADD VALUE cannot run inside the migration env's transaction.
+        with op.get_context().autocommit_block():
+            op.execute("ALTER TYPE job_status_enum ADD VALUE IF NOT EXISTS 'suspended'")
+            op.execute("ALTER TYPE execution_signal_type_enum ADD VALUE IF NOT EXISTS 'pause'")
+            op.execute("ALTER TYPE execution_signal_type_enum ADD VALUE IF NOT EXISTS 'resume'")
+    else:
+        # SQLite rebuilds the column so its reflected VARCHAR length matches the model's widened
+        # Enum(stop, pause, resume); without it the model/migration consistency check (autogenerate)
+        # reports a phantom VARCHAR(4) -> Enum diff. job_status_enum needs no rebuild here.
+        with op.batch_alter_table("execution_signals", recreate="always") as batch_op:
+            batch_op.alter_column(
+                "signal_type",
+                existing_type=_OLD_SIGNAL_ENUM,
+                type_=_NEW_SIGNAL_ENUM,
+                existing_nullable=False,
+            )
+
+
+def downgrade() -> None:
+    # EXPAND: enum ADD VALUE is irreversible without rebuilding the type, so a no-op.
+    pass