feat(workflow): orchestrate resumable dataflow handoffs

README.md

@@ -20,10 +20,13 @@ fields, connected nodes, and permitted loops for correction and retry paths.
 Dataflow uses the same graph contract with its own acyclic transformation
 library.
 
-The current slice deliberately stops before executing process instances.
-Instance state, resumable transitions, human activities, retries, and event
-subscriptions must build on the pinned definition and versioned module
-capabilities rather than bypassing them.
+The executable runtime persists revision-pinned instances, append-only
+transition evidence, resumable human handoffs, retries, cancellation, and
+stable external output references. Dataflow nodes enqueue work through
+Dataflow's lifecycle capability; Workflow never imports Dataflow internals.
+Core's periodic worker reconciles linked runs after re-resolving the stored
+automation principal, while the operator surface exposes progress, review
+actions, evidence references, and direct navigation to Dataflow results.
 
 Definitions can be complete flows or non-runnable templates at system,
 tenant, group, or user scope. Policy resolves whether a definition can be
@@ -33,9 +36,10 @@ and records its hash, node-library version, source scope, actor, Policy
 decision, and effective ancestor limits.
 
 The start-node library distinguishes explicit user, API, scheduled, event, and
-parent-workflow starts. These are definition contracts only until the
-resumable Workflow instance runtime is implemented; the UI reports that
-limitation rather than presenting automation as operational.
+parent-workflow starts. Manual starts and Dataflow/human handoffs are
+operational. The other trigger and generic capability nodes remain explicit
+definition contracts until their event/schedule dispatchers and versioned
+operation providers are implemented.
 
 See [docs/CONCEPT.md](docs/CONCEPT.md) for the complete module concept.
 

docs/CONCEPT.md

@@ -104,19 +104,23 @@ The first executable slice now provides:
 - trigger, activity, review, decision, wait, module-action, Dataflow, and outcome
   nodes
 - API discovery and validation endpoints
+- revision-pinned, idempotent Workflow instances
+- persisted steps and append-only transition evidence
+- durable Dataflow handoff, progress reconciliation, output references,
+  retries, cancellation, and warning/review paths
+- manual activity, review, and wait handoffs with comments and evidence
+- a worker capability with current-authorization rechecks
+- an operator dialog for starting, inspecting, and advancing instances
 
 The next execution slices should provide:
 
 - static workflow definition registration from configuration packages
-- create/read/list workflow instances
-- transition execution with permission checks
+- event, API, schedule, and parent-workflow start dispatchers
 - guard hooks implemented through capability calls
-- command execution records with retry/manual-resolution state
+- registry-driven generic module-action execution records
 - action/effect previews for transitions that call other modules
-- idempotency keys for command execution
 - explicit blocked, retryable, quarantined, manual-required, and
   compensation-required states
-- basic WebUI instance detail and definition viewer
 - dashboard summary provider
 - event emission and audit integration
 
@@ -149,12 +153,16 @@ details.
 
 ## Data Model Sketch
 
-Candidate tables:
+Current tables:
 
 - `workflow_definitions`
-- `workflow_definition_versions`
+- `workflow_definition_revisions`
 - `workflow_instances`
-- `workflow_transition_history`
+- `workflow_instance_steps`
+- `workflow_instance_events`
+
+Future generic action execution and timers may add:
+
 - `workflow_command_records`
 - `workflow_timers`
 
@@ -163,16 +171,14 @@ reference the exact version used at start.
 
 ## WebUI
 
-Initial route contributions:
+Current route contribution:
 
 - `/workflow`
-- `/workflow/instances/:instanceId`
-- `/workflow/definitions/:definitionId`
 
-The UI should show current state, available transitions, pending commands,
-failed handoffs, audit trace, and linked subject records. It should not import
-case/task/template components directly; panels are contributed through core UI
-extension points.
+The route combines the definition editor and a fixed run dialog showing current
+state, available transitions, failed handoffs, comments/evidence, immutable
+event history, and linked Dataflow results. It does not import Dataflow or other
+domain UI components.
 
 ## Tests
 

src/govoplan_workflow/backend/db/__init__.py

@@ -1,9 +1,15 @@
 from govoplan_workflow.backend.db.models import (
     WorkflowDefinition,
     WorkflowDefinitionRevision,
+    WorkflowInstance,
+    WorkflowInstanceEvent,
+    WorkflowInstanceStep,
 )
 
 __all__ = [
     "WorkflowDefinition",
     "WorkflowDefinitionRevision",
+    "WorkflowInstance",
+    "WorkflowInstanceEvent",
+    "WorkflowInstanceStep",
 ]

src/govoplan_workflow/backend/db/models.py

@@ -140,6 +140,11 @@ class WorkflowDefinition(Base, TimestampMixin):
         cascade="all, delete-orphan",
         order_by="WorkflowDefinitionRevision.revision",
     )
+    instances: Mapped[list["WorkflowInstance"]] = relationship(
+        back_populates="definition",
+        cascade="all, delete-orphan",
+        order_by="WorkflowInstance.created_at",
+    )
 
 
 class WorkflowDefinitionRevision(Base, TimestampMixin):
@@ -188,8 +193,244 @@ class WorkflowDefinitionRevision(Base, TimestampMixin):
     definition: Mapped[WorkflowDefinition] = relationship(back_populates="revisions")
 
 
+class WorkflowInstance(Base, TimestampMixin):
+    __tablename__ = "workflow_instances"
+    __table_args__ = (
+        UniqueConstraint(
+            "tenant_id",
+            "definition_id",
+            "idempotency_key",
+            name="uq_workflow_instance_idempotency",
+        ),
+        Index(
+            "ix_workflow_instances_tenant_status",
+            "tenant_id",
+            "status",
+        ),
+        Index(
+            "ix_workflow_instances_reconcile",
+            "status",
+            "updated_at",
+        ),
+    )
+
+    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
+    tenant_id: Mapped[str] = mapped_column(String(36), nullable=False, index=True)
+    definition_id: Mapped[str] = mapped_column(
+        ForeignKey("workflow_definitions.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    definition_revision_id: Mapped[str] = mapped_column(
+        ForeignKey("workflow_definition_revisions.id", ondelete="RESTRICT"),
+        nullable=False,
+        index=True,
+    )
+    status: Mapped[str] = mapped_column(
+        String(30),
+        default="running",
+        nullable=False,
+        index=True,
+    )
+    idempotency_key: Mapped[str] = mapped_column(
+        String(255),
+        nullable=False,
+        index=True,
+    )
+    correlation_id: Mapped[str | None] = mapped_column(
+        String(128),
+        nullable=True,
+        index=True,
+    )
+    current_step_id: Mapped[str | None] = mapped_column(
+        String(36),
+        nullable=True,
+        index=True,
+    )
+    input_: Mapped[dict[str, Any]] = mapped_column(
+        "input",
+        JSON,
+        default=dict,
+        nullable=False,
+    )
+    context_: Mapped[dict[str, Any]] = mapped_column(
+        "context",
+        JSON,
+        default=dict,
+        nullable=False,
+    )
+    output_: Mapped[dict[str, Any]] = mapped_column(
+        "output",
+        JSON,
+        default=dict,
+        nullable=False,
+    )
+    authorization_: Mapped[dict[str, Any]] = mapped_column(
+        "authorization",
+        JSON,
+        default=dict,
+        nullable=False,
+    )
+    started_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+    )
+    finished_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True),
+        nullable=True,
+    )
+    cancellation_requested_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True),
+        nullable=True,
+    )
+    error: Mapped[str | None] = mapped_column(Text, nullable=True)
+    created_by: Mapped[str | None] = mapped_column(
+        String(255),
+        nullable=True,
+        index=True,
+    )
+
+    definition: Mapped[WorkflowDefinition] = relationship(
+        back_populates="instances"
+    )
+    steps: Mapped[list["WorkflowInstanceStep"]] = relationship(
+        back_populates="instance",
+        cascade="all, delete-orphan",
+        order_by="WorkflowInstanceStep.sequence",
+    )
+    events: Mapped[list["WorkflowInstanceEvent"]] = relationship(
+        back_populates="instance",
+        cascade="all, delete-orphan",
+        order_by="WorkflowInstanceEvent.sequence",
+    )
+
+
+class WorkflowInstanceStep(Base, TimestampMixin):
+    __tablename__ = "workflow_instance_steps"
+    __table_args__ = (
+        UniqueConstraint(
+            "instance_id",
+            "sequence",
+            name="uq_workflow_instance_step_sequence",
+        ),
+        Index(
+            "ix_workflow_instance_steps_tenant_status",
+            "tenant_id",
+            "status",
+        ),
+    )
+
+    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
+    tenant_id: Mapped[str] = mapped_column(String(36), nullable=False, index=True)
+    instance_id: Mapped[str] = mapped_column(
+        ForeignKey("workflow_instances.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    sequence: Mapped[int] = mapped_column(Integer, nullable=False)
+    node_id: Mapped[str] = mapped_column(String(120), nullable=False, index=True)
+    node_type: Mapped[str] = mapped_column(String(120), nullable=False, index=True)
+    status: Mapped[str] = mapped_column(
+        String(30),
+        nullable=False,
+        index=True,
+    )
+    attempt: Mapped[int] = mapped_column(Integer, default=1, nullable=False)
+    idempotency_key: Mapped[str] = mapped_column(
+        String(255),
+        nullable=False,
+    )
+    input_: Mapped[dict[str, Any]] = mapped_column(
+        "input",
+        JSON,
+        default=dict,
+        nullable=False,
+    )
+    output_: Mapped[dict[str, Any]] = mapped_column(
+        "output",
+        JSON,
+        default=dict,
+        nullable=False,
+    )
+    handoff: Mapped[dict[str, Any]] = mapped_column(
+        JSON,
+        default=dict,
+        nullable=False,
+    )
+    external_ref: Mapped[str | None] = mapped_column(
+        String(500),
+        nullable=True,
+        index=True,
+    )
+    started_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True),
+        nullable=True,
+    )
+    finished_at: Mapped[datetime | None] = mapped_column(
+        DateTime(timezone=True),
+        nullable=True,
+    )
+    error: Mapped[str | None] = mapped_column(Text, nullable=True)
+    completed_by: Mapped[str | None] = mapped_column(
+        String(255),
+        nullable=True,
+    )
+
+    instance: Mapped[WorkflowInstance] = relationship(back_populates="steps")
+
+
+class WorkflowInstanceEvent(Base):
+    __tablename__ = "workflow_instance_events"
+    __table_args__ = (
+        UniqueConstraint(
+            "instance_id",
+            "sequence",
+            name="uq_workflow_instance_event_sequence",
+        ),
+        Index(
+            "ix_workflow_instance_events_tenant_created",
+            "tenant_id",
+            "created_at",
+        ),
+    )
+
+    id: Mapped[str] = mapped_column(String(36), primary_key=True, default=new_uuid)
+    tenant_id: Mapped[str] = mapped_column(String(36), nullable=False, index=True)
+    instance_id: Mapped[str] = mapped_column(
+        ForeignKey("workflow_instances.id", ondelete="CASCADE"),
+        nullable=False,
+        index=True,
+    )
+    step_id: Mapped[str | None] = mapped_column(
+        String(36),
+        nullable=True,
+        index=True,
+    )
+    sequence: Mapped[int] = mapped_column(Integer, nullable=False)
+    kind: Mapped[str] = mapped_column(String(120), nullable=False, index=True)
+    actor_id: Mapped[str | None] = mapped_column(
+        String(255),
+        nullable=True,
+        index=True,
+    )
+    payload: Mapped[dict[str, Any]] = mapped_column(
+        JSON,
+        default=dict,
+        nullable=False,
+    )
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        nullable=False,
+    )
+
+    instance: Mapped[WorkflowInstance] = relationship(back_populates="events")
+
+
 __all__ = [
     "WorkflowDefinition",
     "WorkflowDefinitionRevision",
+    "WorkflowInstance",
+    "WorkflowInstanceEvent",
+    "WorkflowInstanceStep",
     "new_uuid",
 ]

src/govoplan_workflow/backend/governance.py

@@ -12,6 +12,7 @@ from govoplan_core.core.policy import (
     PolicySourceStep,
     definition_governance_policy,
 )
+from govoplan_core.core.workflows import workflow_runtime_worker
 from govoplan_workflow.backend.db.models import WorkflowDefinition
 
 
@@ -127,6 +128,7 @@ def definition_governance_payload(
     principal: ApiPrincipal,
     registry: object | None,
 ) -> dict[str, object]:
+    runtime_available = workflow_runtime_worker(registry) is not None
     actions = {
         action: definition_decision(
             definition,
@@ -151,10 +153,11 @@ def definition_governance_payload(
         "derived_from_hash": definition.derived_from_hash,
         "derivation_provenance": dict(definition.derivation_provenance),
         "actions": actions,
-        "automation_runtime_available": False,
+        "automation_runtime_available": runtime_available,
         "automation_runtime_reason": (
-            "Workflow start definitions are persisted and governed, but "
-            "automatic instance dispatch requires the Workflow runtime."
+            None
+            if runtime_available
+            else "Automatic reconciliation requires the Workflow runtime worker."
         ),
     }
 

src/govoplan_workflow/backend/manifest.py

@@ -4,6 +4,7 @@ from pathlib import Path
 
 from govoplan_core.core.access import (
     CAPABILITY_ACCESS_DIRECTORY,
+    CAPABILITY_AUTH_AUTOMATION_PRINCIPAL_PROVIDER,
     CAPABILITY_AUTH_PERMISSION_EVALUATOR,
     CAPABILITY_AUTH_PRINCIPAL_RESOLVER,
 )
@@ -28,8 +29,14 @@ from govoplan_core.core.modules import (
 from govoplan_core.core.policy import (
     CAPABILITY_POLICY_DEFINITION_GOVERNANCE,
 )
+from govoplan_core.core.notifications import (
+    CAPABILITY_NOTIFICATIONS_DISPATCH,
+)
 from govoplan_core.core.references import CAPABILITY_ACCESS_REFERENCE_OPTIONS
 from govoplan_core.core.views import CAPABILITY_VIEWS_RESOLVER
+from govoplan_core.core.workflows import (
+    CAPABILITY_WORKFLOW_RUNTIME_WORKER,
+)
 from govoplan_core.db.base import Base
 from govoplan_workflow.backend.db import models as workflow_models
 
@@ -123,6 +130,14 @@ def _router(context: ModuleContext):
     return router
 
 
+def _runtime_worker(context: ModuleContext):
+    from govoplan_workflow.backend.instance_service import (
+        SqlWorkflowRuntimeWorker,
+    )
+
+    return SqlWorkflowRuntimeWorker(registry=context.registry)
+
+
 manifest = ModuleManifest(
     id=MODULE_ID,
     name=MODULE_NAME,
@@ -141,9 +156,11 @@ manifest = ModuleManifest(
     optional_capabilities=(
         CAPABILITY_ACCESS_DIRECTORY,
         CAPABILITY_ACCESS_REFERENCE_OPTIONS,
+        CAPABILITY_AUTH_AUTOMATION_PRINCIPAL_PROVIDER,
         CAPABILITY_AUTH_PRINCIPAL_RESOLVER,
         CAPABILITY_AUTH_PERMISSION_EVALUATOR,
         CAPABILITY_DATAFLOW_RUN_LIFECYCLE,
+        CAPABILITY_NOTIFICATIONS_DISPATCH,
         CAPABILITY_POLICY_DEFINITION_GOVERNANCE,
         CAPABILITY_VIEWS_RESOLVER,
     ),
@@ -151,6 +168,7 @@ manifest = ModuleManifest(
         ModuleInterfaceProvider(name="workflow.definition_graph", version="0.1.0"),
         ModuleInterfaceProvider(name="workflow.node_library", version="0.1.0"),
         ModuleInterfaceProvider(name="workflow.definition_catalogue", version="0.1.0"),
+        ModuleInterfaceProvider(name="workflow.runtime_worker", version=MODULE_VERSION),
     ),
     requires_interfaces=(
         ModuleInterfaceRequirement(
@@ -165,6 +183,18 @@ manifest = ModuleManifest(
             version_max_exclusive="1.0.0",
             optional=True,
         ),
+        ModuleInterfaceRequirement(
+            name="auth.automation_principal",
+            version_min="0.1.0",
+            version_max_exclusive="1.0.0",
+            optional=True,
+        ),
+        ModuleInterfaceRequirement(
+            name=CAPABILITY_NOTIFICATIONS_DISPATCH,
+            version_min="0.1.0",
+            version_max_exclusive="1.0.0",
+            optional=True,
+        ),
         ModuleInterfaceRequirement(
             name="policy.definition_governance",
             version_min="0.1.0",
@@ -211,12 +241,18 @@ manifest = ModuleManifest(
         ),
     ),
     route_factory=_router,
+    capability_factories={
+        CAPABILITY_WORKFLOW_RUNTIME_WORKER: _runtime_worker,
+    },
     migration_spec=MigrationSpec(
         module_id=MODULE_ID,
         metadata=Base.metadata,
         script_location=str(Path(__file__).with_name("migrations") / "versions"),
         retirement_supported=True,
         retirement_provider=drop_table_retirement_provider(
+            workflow_models.WorkflowInstanceEvent,
+            workflow_models.WorkflowInstanceStep,
+            workflow_models.WorkflowInstance,
             workflow_models.WorkflowDefinitionRevision,
             workflow_models.WorkflowDefinition,
             label="Workflow",
@@ -230,6 +266,9 @@ manifest = ModuleManifest(
         persistent_table_uninstall_guard(
             workflow_models.WorkflowDefinition,
             workflow_models.WorkflowDefinitionRevision,
+            workflow_models.WorkflowInstance,
+            workflow_models.WorkflowInstanceStep,
+            workflow_models.WorkflowInstanceEvent,
             label="Workflow",
         ),
     ),

src/govoplan_workflow/backend/migrations/versions/d8f2a5c7e1b4_v0114_workflow_runtime.py

@@ -0,0 +1,213 @@
+"""v0.1.14 Workflow instances and resumable handoffs
+
+Revision ID: d8f2a5c7e1b4
+Revises: c6d8f1a3e5b7
+Create Date: 2026-07-30 00:00:00.000000
+"""
+from __future__ import annotations
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "d8f2a5c7e1b4"
+down_revision = "c6d8f1a3e5b7"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.create_table(
+        "workflow_instances",
+        sa.Column("id", sa.String(length=36), nullable=False),
+        sa.Column("tenant_id", sa.String(length=36), nullable=False),
+        sa.Column("definition_id", sa.String(length=36), nullable=False),
+        sa.Column(
+            "definition_revision_id",
+            sa.String(length=36),
+            nullable=False,
+        ),
+        sa.Column("status", sa.String(length=30), nullable=False),
+        sa.Column("idempotency_key", sa.String(length=255), nullable=False),
+        sa.Column("correlation_id", sa.String(length=128), nullable=True),
+        sa.Column("current_step_id", sa.String(length=36), nullable=True),
+        sa.Column("input", sa.JSON(), nullable=False),
+        sa.Column("context", sa.JSON(), nullable=False),
+        sa.Column("output", sa.JSON(), nullable=False),
+        sa.Column("authorization", sa.JSON(), nullable=False),
+        sa.Column("started_at", sa.DateTime(timezone=True), nullable=False),
+        sa.Column("finished_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column(
+            "cancellation_requested_at",
+            sa.DateTime(timezone=True),
+            nullable=True,
+        ),
+        sa.Column("error", sa.Text(), nullable=True),
+        sa.Column("created_by", sa.String(length=255), nullable=True),
+        sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
+        sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
+        sa.ForeignKeyConstraint(
+            ["definition_id"],
+            ["workflow_definitions.id"],
+            ondelete="CASCADE",
+        ),
+        sa.ForeignKeyConstraint(
+            ["definition_revision_id"],
+            ["workflow_definition_revisions.id"],
+            ondelete="RESTRICT",
+        ),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint(
+            "tenant_id",
+            "definition_id",
+            "idempotency_key",
+            name="uq_workflow_instance_idempotency",
+        ),
+    )
+    for column in (
+        "tenant_id",
+        "definition_id",
+        "definition_revision_id",
+        "status",
+        "idempotency_key",
+        "correlation_id",
+        "current_step_id",
+        "created_by",
+    ):
+        op.create_index(
+            op.f(f"ix_workflow_instances_{column}"),
+            "workflow_instances",
+            [column],
+            unique=False,
+        )
+    op.create_index(
+        "ix_workflow_instances_tenant_status",
+        "workflow_instances",
+        ["tenant_id", "status"],
+        unique=False,
+    )
+    op.create_index(
+        "ix_workflow_instances_reconcile",
+        "workflow_instances",
+        ["status", "updated_at"],
+        unique=False,
+    )
+
+    op.create_table(
+        "workflow_instance_steps",
+        sa.Column("id", sa.String(length=36), nullable=False),
+        sa.Column("tenant_id", sa.String(length=36), nullable=False),
+        sa.Column("instance_id", sa.String(length=36), nullable=False),
+        sa.Column("sequence", sa.Integer(), nullable=False),
+        sa.Column("node_id", sa.String(length=120), nullable=False),
+        sa.Column("node_type", sa.String(length=120), nullable=False),
+        sa.Column("status", sa.String(length=30), nullable=False),
+        sa.Column("attempt", sa.Integer(), nullable=False),
+        sa.Column("idempotency_key", sa.String(length=255), nullable=False),
+        sa.Column("input", sa.JSON(), nullable=False),
+        sa.Column("output", sa.JSON(), nullable=False),
+        sa.Column("handoff", sa.JSON(), nullable=False),
+        sa.Column("external_ref", sa.String(length=500), nullable=True),
+        sa.Column("started_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("finished_at", sa.DateTime(timezone=True), nullable=True),
+        sa.Column("error", sa.Text(), nullable=True),
+        sa.Column("completed_by", sa.String(length=255), nullable=True),
+        sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
+        sa.Column("updated_at", sa.DateTime(timezone=True), nullable=False),
+        sa.ForeignKeyConstraint(
+            ["instance_id"],
+            ["workflow_instances.id"],
+            ondelete="CASCADE",
+        ),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint(
+            "instance_id",
+            "sequence",
+            name="uq_workflow_instance_step_sequence",
+        ),
+    )
+    for column in (
+        "tenant_id",
+        "instance_id",
+        "node_id",
+        "node_type",
+        "status",
+        "external_ref",
+    ):
+        op.create_index(
+            op.f(f"ix_workflow_instance_steps_{column}"),
+            "workflow_instance_steps",
+            [column],
+            unique=False,
+        )
+    op.create_index(
+        "ix_workflow_instance_steps_tenant_status",
+        "workflow_instance_steps",
+        ["tenant_id", "status"],
+        unique=False,
+    )
+
+    op.create_table(
+        "workflow_instance_events",
+        sa.Column("id", sa.String(length=36), nullable=False),
+        sa.Column("tenant_id", sa.String(length=36), nullable=False),
+        sa.Column("instance_id", sa.String(length=36), nullable=False),
+        sa.Column("step_id", sa.String(length=36), nullable=True),
+        sa.Column("sequence", sa.Integer(), nullable=False),
+        sa.Column("kind", sa.String(length=120), nullable=False),
+        sa.Column("actor_id", sa.String(length=255), nullable=True),
+        sa.Column("payload", sa.JSON(), nullable=False),
+        sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
+        sa.ForeignKeyConstraint(
+            ["instance_id"],
+            ["workflow_instances.id"],
+            ondelete="CASCADE",
+        ),
+        sa.PrimaryKeyConstraint("id"),
+        sa.UniqueConstraint(
+            "instance_id",
+            "sequence",
+            name="uq_workflow_instance_event_sequence",
+        ),
+    )
+    for column in (
+        "tenant_id",
+        "instance_id",
+        "step_id",
+        "kind",
+        "actor_id",
+    ):
+        op.create_index(
+            op.f(f"ix_workflow_instance_events_{column}"),
+            "workflow_instance_events",
+            [column],
+            unique=False,
+        )
+    op.create_index(
+        "ix_workflow_instance_events_tenant_created",
+        "workflow_instance_events",
+        ["tenant_id", "created_at"],
+        unique=False,
+    )
+
+
+def downgrade() -> None:
+    op.drop_index(
+        "ix_workflow_instance_events_tenant_created",
+        table_name="workflow_instance_events",
+    )
+    op.drop_table("workflow_instance_events")
+    op.drop_index(
+        "ix_workflow_instance_steps_tenant_status",
+        table_name="workflow_instance_steps",
+    )
+    op.drop_table("workflow_instance_steps")
+    op.drop_index(
+        "ix_workflow_instances_reconcile",
+        table_name="workflow_instances",
+    )
+    op.drop_index(
+        "ix_workflow_instances_tenant_status",
+        table_name="workflow_instances",
+    )
+    op.drop_table("workflow_instances")

src/govoplan_workflow/backend/node_library.py

@@ -243,6 +243,12 @@ WORKFLOW_NODE_TYPES = (
         input_ports=(DefinitionPort(id="input", label="Input"),),
         output_ports=(
             DefinitionPort(id="success", label="Success", required=False),
+            DefinitionPort(id="warning", label="Warning", required=False),
+            DefinitionPort(
+                id="review_required",
+                label="Review required",
+                required=False,
+            ),
             DefinitionPort(id="failure", label="Failure", required=False),
         ),
         config_fields=(
@@ -294,6 +300,12 @@ WORKFLOW_NODE_TYPES = (
         input_ports=(DefinitionPort(id="input", label="Input"),),
         output_ports=(
             DefinitionPort(id="success", label="Success", required=False),
+            DefinitionPort(id="warning", label="Warning", required=False),
+            DefinitionPort(
+                id="review_required",
+                label="Review required",
+                required=False,
+            ),
             DefinitionPort(id="failure", label="Failure", required=False),
         ),
         config_fields=(
@@ -303,9 +315,59 @@ WORKFLOW_NODE_TYPES = (
                 kind="dataflow",
                 required=True,
             ),
+            DefinitionConfigField(
+                id="revision",
+                label="Pinned revision",
+                kind="number",
+                required=True,
+            ),
+            DefinitionConfigField(
+                id="environment",
+                label="Environment",
+                kind="select",
+                required=True,
+                options=(
+                    ("development", "Development"),
+                    ("staging", "Staging"),
+                    ("production", "Production"),
+                ),
+            ),
+            DefinitionConfigField(
+                id="row_limit",
+                label="Output row limit",
+                kind="number",
+                required=True,
+            ),
+            DefinitionConfigField(
+                id="publication_target_ref",
+                label="Publication datasource",
+                kind="text",
+                description=(
+                    "Optional stable Datasource target for materialized "
+                    "output."
+                ),
+            ),
+            DefinitionConfigField(
+                id="warning_policy",
+                label="Warnings",
+                kind="select",
+                required=True,
+                options=(
+                    ("review", "Require review"),
+                    ("continue", "Continue"),
+                ),
+            ),
             DefinitionConfigField(id="input_mapping", label="Input mapping", kind="mapping"),
         ),
-        default_config={"pipeline_ref": "", "input_mapping": {}},
+        default_config={
+            "pipeline_ref": "",
+            "revision": 1,
+            "environment": "development",
+            "row_limit": 500,
+            "publication_target_ref": "",
+            "warning_policy": "review",
+            "input_mapping": {},
+        },
     ),
     DefinitionNodeType(
         type="workflow.end.completed",

src/govoplan_workflow/backend/router.py

@@ -24,6 +24,9 @@ from govoplan_workflow.backend.manifest import (
     ADMIN_SCOPE,
     DEFINITION_READ_SCOPE,
     DEFINITION_WRITE_SCOPE,
+    INSTANCE_READ_SCOPE,
+    INSTANCE_START_SCOPE,
+    INSTANCE_TRANSITION_SCOPE,
 )
 from govoplan_workflow.backend.node_library import WORKFLOW_GRAPH_LIBRARY
 from govoplan_workflow.backend.schemas import (
@@ -40,9 +43,22 @@ from govoplan_workflow.backend.schemas import (
     WorkflowDiagnosticResponse,
     WorkflowGraphValidationRequest,
     WorkflowGraphValidationResponse,
+    WorkflowInstanceListResponse,
+    WorkflowInstanceResponse,
+    WorkflowInstanceStartRequest,
     WorkflowNodeLibraryResponse,
     WorkflowNodeTypeResponse,
     WorkflowPortResponse,
+    WorkflowStepActionRequest,
+)
+from govoplan_workflow.backend.instance_service import (
+    cancel_instance,
+    get_instance,
+    instance_response,
+    list_instances,
+    reconcile_instance,
+    resolve_step,
+    start_instance,
 )
 from govoplan_workflow.backend.runtime import get_registry
 from govoplan_workflow.backend.service import (
@@ -159,6 +175,35 @@ def _audit(
     )
 
 
+def _audit_instance(
+    session: Session,
+    principal: ApiPrincipal,
+    *,
+    action: str,
+    instance_id: str,
+    details: dict[str, object],
+) -> None:
+    audit_event(
+        session,
+        tenant_id=principal.tenant_id,
+        user_id=getattr(principal.user, "id", None),
+        api_key_id=principal.api_key_id,
+        action=action,
+        object_type="workflow_instance",
+        object_id=instance_id,
+        details=details,
+    )
+
+
+def _require_instance_view(instance, principal: ApiPrincipal) -> None:
+    require_definition_action(
+        instance.definition,
+        principal=principal,
+        registry=get_registry(),
+        action="view",
+    )
+
+
 @router.get("/node-types", response_model=WorkflowNodeLibraryResponse)
 def api_node_types(
     principal: ApiPrincipal = Depends(get_api_principal),
@@ -324,6 +369,242 @@ def api_list_definitions(
     )
 
 
+@router.get("/instances", response_model=WorkflowInstanceListResponse)
+def api_list_instances(
+    definition_id: str | None = None,
+    limit: int = Query(default=100, ge=1, le=200),
+    session: Session = Depends(get_session),
+    principal: ApiPrincipal = Depends(get_api_principal),
+) -> WorkflowInstanceListResponse:
+    _require_any_scope(principal, INSTANCE_READ_SCOPE, ADMIN_SCOPE)
+    try:
+        instances = [
+            instance
+            for instance in list_instances(
+                session,
+                tenant_id=principal.tenant_id,
+                definition_id=definition_id,
+                limit=limit,
+            )
+            if definition_decision(
+                instance.definition,
+                principal=principal,
+                registry=get_registry(),
+                action="view",
+            ).allowed
+        ]
+        return WorkflowInstanceListResponse(
+            instances=[
+                instance_response(session, instance)
+                for instance in instances
+            ]
+        )
+    except WorkflowError as exc:
+        raise _http_error(exc) from exc
+
+
+@router.post(
+    "/definitions/{definition_id}/instances",
+    response_model=WorkflowInstanceResponse,
+    status_code=status.HTTP_201_CREATED,
+)
+def api_start_instance(
+    definition_id: str,
+    payload: WorkflowInstanceStartRequest,
+    session: Session = Depends(get_session),
+    principal: ApiPrincipal = Depends(get_api_principal),
+) -> WorkflowInstanceResponse:
+    _require_any_scope(principal, INSTANCE_START_SCOPE, ADMIN_SCOPE)
+    try:
+        instance, replayed = start_instance(
+            session,
+            tenant_id=principal.tenant_id,
+            definition_id=definition_id,
+            actor_id=_actor_id(principal),
+            principal=principal,
+            registry=get_registry(),
+            payload=payload,
+        )
+    except WorkflowError as exc:
+        raise _http_error(exc) from exc
+    _audit_instance(
+        session,
+        principal,
+        action=(
+            "workflow.instance.replayed"
+            if replayed
+            else "workflow.instance.started"
+        ),
+        instance_id=instance.id,
+        details={
+            "definition_id": instance.definition_id,
+            "definition_revision_id": instance.definition_revision_id,
+            "idempotency_key": instance.idempotency_key,
+        },
+    )
+    response = instance_response(session, instance, replayed=replayed)
+    session.commit()
+    return response
+
+
+@router.get(
+    "/instances/{instance_id}",
+    response_model=WorkflowInstanceResponse,
+)
+def api_get_instance(
+    instance_id: str,
+    session: Session = Depends(get_session),
+    principal: ApiPrincipal = Depends(get_api_principal),
+) -> WorkflowInstanceResponse:
+    _require_any_scope(principal, INSTANCE_READ_SCOPE, ADMIN_SCOPE)
+    try:
+        instance = get_instance(
+            session,
+            tenant_id=principal.tenant_id,
+            instance_id=instance_id,
+        )
+        _require_instance_view(instance, principal)
+        return instance_response(session, instance)
+    except PermissionError as exc:
+        raise _governance_http_error(exc) from exc
+    except WorkflowError as exc:
+        raise _http_error(exc) from exc
+
+
+@router.post(
+    "/instances/{instance_id}/reconcile",
+    response_model=WorkflowInstanceResponse,
+)
+def api_reconcile_instance(
+    instance_id: str,
+    session: Session = Depends(get_session),
+    principal: ApiPrincipal = Depends(get_api_principal),
+) -> WorkflowInstanceResponse:
+    _require_any_scope(principal, INSTANCE_TRANSITION_SCOPE, ADMIN_SCOPE)
+    try:
+        instance = get_instance(
+            session,
+            tenant_id=principal.tenant_id,
+            instance_id=instance_id,
+            for_update=True,
+        )
+        _require_instance_view(instance, principal)
+        changed = reconcile_instance(
+            session,
+            instance=instance,
+            principal=principal,
+            registry=get_registry(),
+            actor_id=_actor_id(principal),
+        )
+    except PermissionError as exc:
+        raise _governance_http_error(exc) from exc
+    except WorkflowError as exc:
+        raise _http_error(exc) from exc
+    if changed:
+        _audit_instance(
+            session,
+            principal,
+            action="workflow.instance.reconciled",
+            instance_id=instance.id,
+            details={
+                "status": instance.status,
+                "current_step_id": instance.current_step_id,
+            },
+        )
+    response = instance_response(session, instance)
+    session.commit()
+    return response
+
+
+@router.post(
+    "/instances/{instance_id}/steps/{step_id}/actions",
+    response_model=WorkflowInstanceResponse,
+)
+def api_resolve_instance_step(
+    instance_id: str,
+    step_id: str,
+    payload: WorkflowStepActionRequest,
+    session: Session = Depends(get_session),
+    principal: ApiPrincipal = Depends(get_api_principal),
+) -> WorkflowInstanceResponse:
+    _require_any_scope(principal, INSTANCE_TRANSITION_SCOPE, ADMIN_SCOPE)
+    try:
+        existing = get_instance(
+            session,
+            tenant_id=principal.tenant_id,
+            instance_id=instance_id,
+        )
+        _require_instance_view(existing, principal)
+        instance = resolve_step(
+            session,
+            tenant_id=principal.tenant_id,
+            instance_id=instance_id,
+            step_id=step_id,
+            actor_id=_actor_id(principal),
+            principal=principal,
+            registry=get_registry(),
+            payload=payload,
+        )
+    except PermissionError as exc:
+        raise _governance_http_error(exc) from exc
+    except WorkflowError as exc:
+        raise _http_error(exc) from exc
+    _audit_instance(
+        session,
+        principal,
+        action=f"workflow.instance.{payload.action}",
+        instance_id=instance.id,
+        details={
+            "step_id": step_id,
+            "status": instance.status,
+        },
+    )
+    response = instance_response(session, instance)
+    session.commit()
+    return response
+
+
+@router.post(
+    "/instances/{instance_id}/cancel",
+    response_model=WorkflowInstanceResponse,
+)
+def api_cancel_instance(
+    instance_id: str,
+    session: Session = Depends(get_session),
+    principal: ApiPrincipal = Depends(get_api_principal),
+) -> WorkflowInstanceResponse:
+    _require_any_scope(principal, INSTANCE_TRANSITION_SCOPE, ADMIN_SCOPE)
+    try:
+        instance = get_instance(
+            session,
+            tenant_id=principal.tenant_id,
+            instance_id=instance_id,
+        )
+        _require_instance_view(instance, principal)
+        instance = cancel_instance(
+            session,
+            tenant_id=principal.tenant_id,
+            instance_id=instance_id,
+            actor_id=_actor_id(principal),
+            principal=principal,
+            registry=get_registry(),
+        )
+    except PermissionError as exc:
+        raise _governance_http_error(exc) from exc
+    except WorkflowError as exc:
+        raise _http_error(exc) from exc
+    _audit_instance(
+        session,
+        principal,
+        action="workflow.instance.cancelled",
+        instance_id=instance.id,
+        details={"status": instance.status},
+    )
+    response = instance_response(session, instance)
+    session.commit()
+    return response
+
+
 @router.post(
     "/definitions",
     response_model=WorkflowDefinitionResponse,

src/govoplan_workflow/backend/schemas.py

@@ -225,3 +225,99 @@ class WorkflowDefinitionActivateRequest(BaseModel):
 class WorkflowDefinitionDeleteResponse(BaseModel):
     deleted: bool
     definition_id: str
+
+
+WorkflowInstanceStatus = Literal[
+    "running",
+    "waiting",
+    "completed",
+    "failed",
+    "cancelled",
+]
+WorkflowStepStatus = Literal[
+    "running",
+    "waiting",
+    "completed",
+    "failed",
+    "cancelled",
+    "superseded",
+]
+
+
+class WorkflowInstanceStartRequest(BaseModel):
+    idempotency_key: str = Field(min_length=1, max_length=255)
+    input: dict[str, Any] = Field(default_factory=dict)
+    correlation_id: str | None = Field(default=None, max_length=128)
+
+
+class WorkflowStepActionRequest(BaseModel):
+    action: Literal[
+        "complete",
+        "approve",
+        "changes",
+        "reject",
+        "resume",
+        "retry",
+        "cancel",
+    ]
+    output: dict[str, Any] = Field(default_factory=dict)
+    evidence: list[str] = Field(default_factory=list, max_length=100)
+    comment: str | None = Field(default=None, max_length=4_000)
+
+
+class WorkflowInstanceStepResponse(BaseModel):
+    id: str
+    sequence: int
+    node_id: str
+    node_type: str
+    status: WorkflowStepStatus
+    attempt: int
+    input: dict[str, Any]
+    output: dict[str, Any]
+    handoff: dict[str, Any]
+    external_ref: str | None
+    started_at: datetime | None
+    finished_at: datetime | None
+    error: str | None
+    completed_by: str | None
+    created_at: datetime
+    updated_at: datetime
+
+
+class WorkflowInstanceEventResponse(BaseModel):
+    id: str
+    sequence: int
+    step_id: str | None
+    kind: str
+    actor_id: str | None
+    payload: dict[str, Any]
+    created_at: datetime
+
+
+class WorkflowInstanceResponse(BaseModel):
+    id: str
+    definition_id: str
+    definition_name: str
+    definition_revision: int
+    definition_hash: str
+    status: WorkflowInstanceStatus
+    idempotency_key: str
+    correlation_id: str | None
+    current_step_id: str | None
+    input: dict[str, Any]
+    context: dict[str, Any]
+    output: dict[str, Any]
+    started_at: datetime
+    finished_at: datetime | None
+    cancellation_requested_at: datetime | None
+    error: str | None
+    created_by: str | None
+    created_at: datetime
+    updated_at: datetime
+    steps: list[WorkflowInstanceStepResponse]
+    events: list[WorkflowInstanceEventResponse]
+    replayed: bool = False
+
+
+class WorkflowInstanceListResponse(BaseModel):
+    instances: list[WorkflowInstanceResponse]

tests/test_instance_service.py

@@ -0,0 +1,482 @@
+from __future__ import annotations
+
+from dataclasses import replace
+import unittest
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import Session, sessionmaker
+
+from govoplan_core.auth import ApiPrincipal
+from govoplan_core.core.access import (
+    CAPABILITY_AUTH_AUTOMATION_PRINCIPAL_PROVIDER,
+    PrincipalRef,
+)
+from govoplan_core.core.automation import AutomationPrincipalResolution
+from govoplan_core.core.dataflows import (
+    CAPABILITY_DATAFLOW_RUN_LIFECYCLE,
+    DataflowRunDescriptor,
+)
+from govoplan_core.db.base import Base
+from govoplan_workflow.backend.db.models import (
+    WorkflowDefinition,
+    WorkflowDefinitionRevision,
+    WorkflowInstance,
+    WorkflowInstanceEvent,
+    WorkflowInstanceStep,
+)
+from govoplan_workflow.backend.instance_service import (
+    SqlWorkflowRuntimeWorker,
+    cancel_instance,
+    instance_response,
+    reconcile_instance,
+    resolve_step,
+    start_instance,
+)
+from govoplan_workflow.backend.schemas import (
+    WorkflowDefinitionCreateRequest,
+    WorkflowEdge,
+    WorkflowGraph,
+    WorkflowInstanceStartRequest,
+    WorkflowNode,
+    WorkflowStepActionRequest,
+)
+from govoplan_workflow.backend.service import (
+    WorkflowConflictError,
+    activate_definition,
+    create_definition,
+)
+
+
+def principal() -> ApiPrincipal:
+    return ApiPrincipal(
+        principal=PrincipalRef(
+            account_id="account-1",
+            membership_id="membership-1",
+            tenant_id="tenant-1",
+            scopes=frozenset(
+                {
+                    "workflow:definition:read",
+                    "workflow:instance:read",
+                    "workflow:instance:start",
+                    "workflow:instance:transition",
+                    "dataflow:pipeline:run",
+                }
+            ),
+        ),
+        account=object(),
+        user=object(),
+    )
+
+
+def runtime_graph() -> WorkflowGraph:
+    return WorkflowGraph(
+        nodes=[
+            WorkflowNode(
+                id="start",
+                type="workflow.start.manual",
+                label="Start",
+                config={"input_schema_ref": ""},
+            ),
+            WorkflowNode(
+                id="flow",
+                type="workflow.dataflow",
+                label="Prepare evidence",
+                config={
+                    "pipeline_ref": "pipeline:pipeline-1",
+                    "revision": 3,
+                    "environment": "development",
+                    "row_limit": 250,
+                    "publication_target_ref": "",
+                    "warning_policy": "review",
+                    "input_mapping": {},
+                },
+            ),
+            WorkflowNode(
+                id="complete",
+                type="workflow.end.completed",
+                label="Complete",
+                config={"output_mapping": {}},
+            ),
+            WorkflowNode(
+                id="cancelled",
+                type="workflow.end.cancelled",
+                label="Rejected",
+                config={"reason": "Rejected during review"},
+            ),
+        ],
+        edges=[
+            WorkflowEdge(
+                id="start-flow",
+                source="start",
+                target="flow",
+            ),
+            WorkflowEdge(
+                id="flow-complete",
+                source="flow",
+                source_port="success",
+                target="complete",
+            ),
+            WorkflowEdge(
+                id="flow-warning",
+                source="flow",
+                source_port="warning",
+                target="complete",
+            ),
+            WorkflowEdge(
+                id="flow-review",
+                source="flow",
+                source_port="review_required",
+                target="complete",
+            ),
+            WorkflowEdge(
+                id="flow-failure",
+                source="flow",
+                source_port="failure",
+                target="cancelled",
+            ),
+        ],
+    )
+
+
+class FakeDataflowLifecycle:
+    def __init__(self) -> None:
+        self.runs: dict[str, DataflowRunDescriptor] = {}
+        self.requests = []
+        self.cancelled: list[str] = []
+
+    def start_run(self, _session, _principal, *, request):
+        self.requests.append(request)
+        run_ref = f"run:{len(self.requests)}"
+        descriptor = DataflowRunDescriptor(
+            ref=run_ref,
+            pipeline_ref=request.pipeline_ref,
+            revision=request.revision,
+            status="queued",
+            definition_hash="definition-hash",
+            executor_version="test",
+            metadata={"progress_percent": 0, "progress_phase": "queued"},
+        )
+        self.runs[run_ref] = descriptor
+        return descriptor
+
+    def get_run(self, _session, _principal, *, run_ref):
+        return self.runs.get(run_ref)
+
+    def cancel_run(self, _session, _principal, *, run_ref):
+        descriptor = self.runs[run_ref]
+        descriptor = replace(descriptor, status="cancelled")
+        self.runs[run_ref] = descriptor
+        self.cancelled.append(run_ref)
+        return descriptor
+
+    def finish(
+        self,
+        run_ref: str,
+        *,
+        diagnostics: list[dict[str, object]] | None = None,
+    ) -> None:
+        self.runs[run_ref] = replace(
+            self.runs[run_ref],
+            status="succeeded",
+            output_publication_ref="publication:1",
+            output_datasource_ref="datasource:1",
+            output_materialization_ref="materialization:1",
+            input_row_count=12,
+            output_row_count=10,
+            metadata={"diagnostics": diagnostics or []},
+        )
+
+    def fail(self, run_ref: str) -> None:
+        self.runs[run_ref] = replace(
+            self.runs[run_ref],
+            status="failed",
+            error="Data quality gate failed.",
+        )
+
+
+class FakeAutomationProvider:
+    def __init__(self) -> None:
+        self.requests = []
+
+    def resolve_automation_principal(self, _session, *, request):
+        self.requests.append(request)
+        return AutomationPrincipalResolution(
+            allowed=True,
+            principal=principal(),
+            granted_scopes=request.grant_scopes,
+            provenance={"status": "rechecked"},
+        )
+
+
+class Registry:
+    def __init__(
+        self,
+        dataflow: FakeDataflowLifecycle,
+        automation: FakeAutomationProvider | None = None,
+    ) -> None:
+        self.dataflow = dataflow
+        self.automation = automation
+
+    def has_capability(self, name: str) -> bool:
+        return name == CAPABILITY_DATAFLOW_RUN_LIFECYCLE or (
+            name == CAPABILITY_AUTH_AUTOMATION_PRINCIPAL_PROVIDER
+            and self.automation is not None
+        )
+
+    def capability(self, name: str):
+        if name == CAPABILITY_DATAFLOW_RUN_LIFECYCLE:
+            return self.dataflow
+        if (
+            name == CAPABILITY_AUTH_AUTOMATION_PRINCIPAL_PROVIDER
+            and self.automation is not None
+        ):
+            return self.automation
+        raise KeyError(name)
+
+
+class WorkflowInstanceServiceTests(unittest.TestCase):
+    def setUp(self) -> None:
+        self.engine = create_engine("sqlite:///:memory:")
+        Base.metadata.create_all(
+            self.engine,
+            tables=[
+                WorkflowDefinition.__table__,
+                WorkflowDefinitionRevision.__table__,
+                WorkflowInstance.__table__,
+                WorkflowInstanceStep.__table__,
+                WorkflowInstanceEvent.__table__,
+            ],
+        )
+        self.Session = sessionmaker(bind=self.engine)
+        self.session: Session = self.Session()
+        self.dataflow = FakeDataflowLifecycle()
+        self.registry = Registry(self.dataflow)
+        self.definition = create_definition(
+            self.session,
+            tenant_id="tenant-1",
+            actor_id="account-1",
+            payload=WorkflowDefinitionCreateRequest(
+                name="Monthly governed processing",
+                graph=runtime_graph(),
+            ),
+        )
+        activate_definition(
+            self.session,
+            tenant_id="tenant-1",
+            definition_id=self.definition.id,
+            actor_id="account-1",
+            revision=1,
+        )
+        self.session.commit()
+
+    def tearDown(self) -> None:
+        self.session.close()
+        Base.metadata.drop_all(
+            self.engine,
+            tables=[
+                WorkflowInstanceEvent.__table__,
+                WorkflowInstanceStep.__table__,
+                WorkflowInstance.__table__,
+                WorkflowDefinitionRevision.__table__,
+                WorkflowDefinition.__table__,
+            ],
+        )
+        self.engine.dispose()
+
+    def _start(self, key: str = "request-1") -> WorkflowInstance:
+        instance, replayed = start_instance(
+            self.session,
+            tenant_id="tenant-1",
+            definition_id=self.definition.id,
+            actor_id="account-1",
+            principal=principal(),
+            registry=self.registry,
+            payload=WorkflowInstanceStartRequest(
+                idempotency_key=key,
+                input={"case_id": "case-1"},
+                correlation_id="correlation-1",
+            ),
+        )
+        self.assertFalse(replayed)
+        return instance
+
+    def test_start_pins_revision_and_replays_idempotently(self) -> None:
+        instance = self._start()
+        replayed, was_replayed = start_instance(
+            self.session,
+            tenant_id="tenant-1",
+            definition_id=self.definition.id,
+            actor_id="account-1",
+            principal=principal(),
+            registry=self.registry,
+            payload=WorkflowInstanceStartRequest(
+                idempotency_key="request-1",
+                input={"case_id": "case-1"},
+                correlation_id="correlation-1",
+            ),
+        )
+
+        self.assertTrue(was_replayed)
+        self.assertEqual(instance.id, replayed.id)
+        self.assertEqual("waiting", instance.status)
+        self.assertEqual(1, len(self.dataflow.requests))
+        response = instance_response(self.session, instance)
+        self.assertEqual([1, 2], [step.sequence for step in response.steps])
+        self.assertEqual("run:1", response.steps[-1].external_ref)
+        self.assertGreaterEqual(len(response.events), 4)
+
+        with self.assertRaises(WorkflowConflictError):
+            start_instance(
+                self.session,
+                tenant_id="tenant-1",
+                definition_id=self.definition.id,
+                actor_id="account-1",
+                principal=principal(),
+                registry=self.registry,
+                payload=WorkflowInstanceStartRequest(
+                    idempotency_key="request-1",
+                    input={"case_id": "another-case"},
+                    correlation_id="correlation-1",
+                ),
+            )
+
+    def test_reconcile_completes_with_stable_dataflow_output_refs(self) -> None:
+        instance = self._start()
+        self.dataflow.finish("run:1")
+
+        changed = reconcile_instance(
+            self.session,
+            instance=instance,
+            principal=principal(),
+            registry=self.registry,
+            actor_id="account-1",
+        )
+        response = instance_response(self.session, instance)
+
+        self.assertTrue(changed)
+        self.assertEqual("completed", response.status)
+        flow_output = response.context["steps"]["flow"]
+        self.assertEqual("publication:1", flow_output["output_publication_ref"])
+        self.assertEqual("datasource:1", flow_output["output_datasource_ref"])
+        self.assertEqual(
+            "materialization:1",
+            flow_output["output_materialization_ref"],
+        )
+        self.assertEqual("workflow.instance.completed", response.events[-1].kind)
+
+    def test_warning_requires_review_and_approve_resumes(self) -> None:
+        instance = self._start()
+        self.dataflow.finish(
+            "run:1",
+            diagnostics=[
+                {
+                    "severity": "warning",
+                    "code": "review.required",
+                    "message": "Verify unmatched records.",
+                }
+            ],
+        )
+        reconcile_instance(
+            self.session,
+            instance=instance,
+            principal=principal(),
+            registry=self.registry,
+        )
+        step_id = str(instance.current_step_id)
+
+        self.assertEqual(
+            "review_required",
+            instance_response(self.session, instance).steps[-1].handoff["state"],
+        )
+        resolved = resolve_step(
+            self.session,
+            tenant_id="tenant-1",
+            instance_id=instance.id,
+            step_id=step_id,
+            actor_id="account-1",
+            principal=principal(),
+            registry=self.registry,
+            payload=WorkflowStepActionRequest(
+                action="approve",
+                comment="Evidence verified.",
+                evidence=["publication:1"],
+            ),
+        )
+
+        self.assertEqual("completed", resolved.status)
+
+    def test_failure_can_retry_and_reject_invalid_actions(self) -> None:
+        instance = self._start()
+        self.dataflow.fail("run:1")
+        reconcile_instance(
+            self.session,
+            instance=instance,
+            principal=principal(),
+            registry=self.registry,
+        )
+        step_id = str(instance.current_step_id)
+
+        with self.assertRaises(WorkflowConflictError):
+            resolve_step(
+                self.session,
+                tenant_id="tenant-1",
+                instance_id=instance.id,
+                step_id=step_id,
+                actor_id="account-1",
+                principal=principal(),
+                registry=self.registry,
+                payload=WorkflowStepActionRequest(action="approve"),
+            )
+        retried = resolve_step(
+            self.session,
+            tenant_id="tenant-1",
+            instance_id=instance.id,
+            step_id=step_id,
+            actor_id="account-1",
+            principal=principal(),
+            registry=self.registry,
+            payload=WorkflowStepActionRequest(action="retry"),
+        )
+
+        self.assertEqual("waiting", retried.status)
+        self.assertEqual(2, len(self.dataflow.requests))
+        self.assertEqual("run:2", retried.steps[-1].external_ref)
+        self.assertEqual("superseded", retried.steps[-2].status)
+
+    def test_cancel_propagates_to_linked_dataflow(self) -> None:
+        instance = self._start()
+
+        cancelled = cancel_instance(
+            self.session,
+            tenant_id="tenant-1",
+            instance_id=instance.id,
+            actor_id="account-1",
+            principal=principal(),
+            registry=self.registry,
+        )
+
+        self.assertEqual("cancelled", cancelled.status)
+        self.assertEqual(["run:1"], self.dataflow.cancelled)
+
+    def test_worker_rechecks_authorization_before_reconciling(self) -> None:
+        instance = self._start()
+        self.session.commit()
+        self.dataflow.finish("run:1")
+        automation = FakeAutomationProvider()
+        worker = SqlWorkflowRuntimeWorker(
+            registry=Registry(self.dataflow, automation),
+        )
+
+        summary = worker.reconcile_pending(self.session)
+
+        self.assertEqual(1, summary["advanced"])
+        self.assertEqual("completed", instance.status)
+        self.assertEqual(1, len(automation.requests))
+        self.assertEqual(
+            "rechecked",
+            instance.authorization_["last_resolution"]["status"],
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_manifest.py

@@ -5,8 +5,12 @@ import unittest
 from govoplan_workflow.backend.manifest import (
     DEFINITION_READ_SCOPE,
     DEFINITION_WRITE_SCOPE,
+    INSTANCE_START_SCOPE,
     get_manifest,
 )
+from govoplan_core.core.workflows import (
+    CAPABILITY_WORKFLOW_RUNTIME_WORKER,
+)
 
 
 class WorkflowManifestTests(unittest.TestCase):
@@ -26,6 +30,18 @@ class WorkflowManifestTests(unittest.TestCase):
             DEFINITION_WRITE_SCOPE,
             {item.scope for item in manifest.permissions},
         )
+        self.assertIn(
+            INSTANCE_START_SCOPE,
+            {item.scope for item in manifest.permissions},
+        )
+        self.assertIn(
+            "workflow.runtime_worker",
+            {item.name for item in manifest.provides_interfaces},
+        )
+        self.assertIn(
+            CAPABILITY_WORKFLOW_RUNTIME_WORKER,
+            manifest.capability_factories,
+        )
         self.assertEqual(
             "@govoplan/workflow-webui",
             manifest.frontend.package_name if manifest.frontend else None,

tests/test_migrations.py

@@ -26,13 +26,16 @@ class WorkflowMigrationTests(unittest.TestCase):
             try:
                 with engine.connect() as connection:
                     self.assertIn(
-                        "c6d8f1a3e5b7",
+                        "d8f2a5c7e1b4",
                         set(MigrationContext.configure(connection).get_current_heads()),
                     )
                     self.assertEqual(
                         {
                             "workflow_definition_revisions",
                             "workflow_definitions",
+                            "workflow_instance_events",
+                            "workflow_instance_steps",
+                            "workflow_instances",
                         },
                         {
                             name

webui/src/api/workflow.ts

@@ -84,6 +84,75 @@ export type WorkflowGovernance = {
   automation_runtime_reason?: string | null;
 };
 
+export type WorkflowInstanceStatus =
+  | "running"
+  | "waiting"
+  | "completed"
+  | "failed"
+  | "cancelled";
+
+export type WorkflowStepStatus =
+  | "running"
+  | "waiting"
+  | "completed"
+  | "failed"
+  | "cancelled"
+  | "superseded";
+
+export type WorkflowInstanceStep = {
+  id: string;
+  sequence: number;
+  node_id: string;
+  node_type: string;
+  status: WorkflowStepStatus;
+  attempt: number;
+  input: Record<string, unknown>;
+  output: Record<string, unknown>;
+  handoff: Record<string, unknown>;
+  external_ref?: string | null;
+  started_at?: string | null;
+  finished_at?: string | null;
+  error?: string | null;
+  completed_by?: string | null;
+  created_at: string;
+  updated_at: string;
+};
+
+export type WorkflowInstanceEvent = {
+  id: string;
+  sequence: number;
+  step_id?: string | null;
+  kind: string;
+  actor_id?: string | null;
+  payload: Record<string, unknown>;
+  created_at: string;
+};
+
+export type WorkflowInstance = {
+  id: string;
+  definition_id: string;
+  definition_name: string;
+  definition_revision: number;
+  definition_hash: string;
+  status: WorkflowInstanceStatus;
+  idempotency_key: string;
+  correlation_id?: string | null;
+  current_step_id?: string | null;
+  input: Record<string, unknown>;
+  context: Record<string, unknown>;
+  output: Record<string, unknown>;
+  started_at: string;
+  finished_at?: string | null;
+  cancellation_requested_at?: string | null;
+  error?: string | null;
+  created_by?: string | null;
+  created_at: string;
+  updated_at: string;
+  steps: WorkflowInstanceStep[];
+  events: WorkflowInstanceEvent[];
+  replayed: boolean;
+};
+
 export type WorkflowDefinitionPayload = {
   name: string;
   description?: string | null;
@@ -232,3 +301,89 @@ export function workflowScopeReferenceProvider(
     { scope_type: scopeType }
   );
 }
+
+export async function listWorkflowInstances(
+  settings: ApiSettings,
+  definitionId?: string | null
+): Promise<WorkflowInstance[]> {
+  const params = new URLSearchParams();
+  if (definitionId) params.set("definition_id", definitionId);
+  const query = params.size ? `?${params.toString()}` : "";
+  const response = await apiFetch<{ instances: WorkflowInstance[] }>(
+    settings,
+    `/api/v1/workflow/instances${query}`
+  );
+  return response.instances;
+}
+
+export function startWorkflowInstance(
+  settings: ApiSettings,
+  definitionId: string,
+  payload: {
+    idempotency_key: string;
+    input?: Record<string, unknown>;
+    correlation_id?: string | null;
+  }
+): Promise<WorkflowInstance> {
+  return apiFetch(
+    settings,
+    `/api/v1/workflow/definitions/${encodeURIComponent(definitionId)}/instances`,
+    {
+      method: "POST",
+      body: JSON.stringify(payload)
+    }
+  );
+}
+
+export function getWorkflowInstance(
+  settings: ApiSettings,
+  instanceId: string
+): Promise<WorkflowInstance> {
+  return apiFetch(
+    settings,
+    `/api/v1/workflow/instances/${encodeURIComponent(instanceId)}`
+  );
+}
+
+export function reconcileWorkflowInstance(
+  settings: ApiSettings,
+  instanceId: string
+): Promise<WorkflowInstance> {
+  return apiFetch(
+    settings,
+    `/api/v1/workflow/instances/${encodeURIComponent(instanceId)}/reconcile`,
+    { method: "POST" }
+  );
+}
+
+export function resolveWorkflowStep(
+  settings: ApiSettings,
+  instanceId: string,
+  stepId: string,
+  payload: {
+    action: "complete" | "approve" | "changes" | "reject" | "resume" | "retry" | "cancel";
+    output?: Record<string, unknown>;
+    evidence?: string[];
+    comment?: string | null;
+  }
+): Promise<WorkflowInstance> {
+  return apiFetch(
+    settings,
+    `/api/v1/workflow/instances/${encodeURIComponent(instanceId)}/steps/${encodeURIComponent(stepId)}/actions`,
+    {
+      method: "POST",
+      body: JSON.stringify(payload)
+    }
+  );
+}
+
+export function cancelWorkflowInstance(
+  settings: ApiSettings,
+  instanceId: string
+): Promise<WorkflowInstance> {
+  return apiFetch(
+    settings,
+    `/api/v1/workflow/instances/${encodeURIComponent(instanceId)}/cancel`,
+    { method: "POST" }
+  );
+}

webui/src/features/workflow/WorkflowPage.tsx

@@ -10,6 +10,7 @@ import {
   CheckCircle2,
   CopyPlus,
   GitFork,
+  ListChecks,
   Plus,
   RefreshCw,
   RotateCcw,
@@ -57,6 +58,7 @@ import WorkflowCanvas, {
   updateWorkflowGraphNode
 } from "./WorkflowCanvas";
 import WorkflowInspector from "./WorkflowInspector";
+import WorkflowRunsDialog from "./WorkflowRunsDialog";
 import {
   FALLBACK_WORKFLOW_LIBRARY,
   draftFromDefinition,
@@ -103,6 +105,7 @@ export default function WorkflowPage({
   const [deleteOpen, setDeleteOpen] = useState(false);
   const [definitionSettingsOpen, setDefinitionSettingsOpen] = useState(false);
   const [deriveOpen, setDeriveOpen] = useState(false);
+  const [runsOpen, setRunsOpen] = useState(false);
 
   const canWrite = hasScope(auth, "workflow:definition:write")
     || hasScope(auth, "workflow:instance:admin");
@@ -114,6 +117,18 @@ export default function WorkflowPage({
     && canWrite
     && draft.governance?.actions.derive?.allowed
   );
+  const canStart = Boolean(
+    draft?.id
+    && (hasScope(auth, "workflow:instance:start")
+      || hasScope(auth, "workflow:instance:admin"))
+    && draft.governance?.actions.start?.allowed !== false
+  );
+  const canTransition = hasScope(auth, "workflow:instance:transition")
+    || hasScope(auth, "workflow:instance:admin");
+  const selectedDefinition = useMemo(
+    () => definitions.find((item) => item.id === draft?.id) ?? null,
+    [definitions, draft?.id]
+  );
   const dirty = Boolean(draft)
     && workflowFingerprint(draft) !== workflowFingerprint(savedDraft);
   const displayedGraph = historicalRevision?.graph ?? draft?.graph ?? null;
@@ -531,6 +546,14 @@ export default function WorkflowPage({
                   <Button onClick={() => void validate()} disabled={working}>
                     <CheckCircle2 size={16} /> Validate
                   </Button>
+                  {draft.id ? (
+                    <Button
+                      onClick={() => setRunsOpen(true)}
+                      disabled={dirty || historicalRevision !== null}
+                    >
+                      <ListChecks size={16} /> Runs
+                    </Button>
+                  ) : null}
                   <IconButton
                     label="Definition settings"
                     icon={<Settings2 size={16} />}
@@ -748,6 +771,14 @@ export default function WorkflowPage({
           setSuccess("Created a pinned scoped copy.");
         }}
       />
+      <WorkflowRunsDialog
+        open={runsOpen}
+        settings={settings}
+        definition={selectedDefinition}
+        canStart={canStart}
+        canTransition={canTransition}
+        onClose={() => setRunsOpen(false)}
+      />
     </main>
   );
 }

webui/src/features/workflow/WorkflowRunsDialog.tsx

@@ -0,0 +1,516 @@
+import {
+  useCallback,
+  useEffect,
+  useMemo,
+  useState
+} from "react";
+import {
+  ExternalLink,
+  Play,
+  RefreshCw,
+  RotateCcw,
+  XCircle
+} from "lucide-react";
+import {
+  Button,
+  ConfirmDialog,
+  Dialog,
+  DismissibleAlert,
+  FormField,
+  IconButton,
+  LoadingFrame,
+  StatusBadge,
+  type ApiSettings
+} from "@govoplan/core-webui";
+import {
+  cancelWorkflowInstance,
+  listWorkflowInstances,
+  reconcileWorkflowInstance,
+  resolveWorkflowStep,
+  startWorkflowInstance,
+  type WorkflowDefinition,
+  type WorkflowInstance,
+  type WorkflowInstanceStep
+} from "../../api/workflow";
+
+type WorkflowAction =
+  | "complete"
+  | "approve"
+  | "changes"
+  | "reject"
+  | "resume"
+  | "retry"
+  | "cancel";
+
+export default function WorkflowRunsDialog({
+  open,
+  settings,
+  definition,
+  canStart,
+  canTransition,
+  onClose
+}: {
+  open: boolean;
+  settings: ApiSettings;
+  definition: WorkflowDefinition | null;
+  canStart: boolean;
+  canTransition: boolean;
+  onClose: () => void;
+}) {
+  const [instances, setInstances] = useState<WorkflowInstance[]>([]);
+  const [selectedId, setSelectedId] = useState<string | null>(null);
+  const [loading, setLoading] = useState(false);
+  const [working, setWorking] = useState(false);
+  const [error, setError] = useState("");
+  const [comment, setComment] = useState("");
+  const [evidence, setEvidence] = useState("");
+  const [cancelOpen, setCancelOpen] = useState(false);
+
+  const selected = useMemo(
+    () => instances.find((item) => item.id === selectedId) ?? instances[0] ?? null,
+    [instances, selectedId]
+  );
+  const currentStep = useMemo(
+    () => currentInstanceStep(selected),
+    [selected]
+  );
+  const allowedActions = useMemo(
+    () => handoffActions(currentStep),
+    [currentStep]
+  );
+
+  const mergeInstance = useCallback((instance: WorkflowInstance) => {
+    setInstances((current) => [
+      instance,
+      ...current.filter((item) => item.id !== instance.id)
+    ]);
+    setSelectedId(instance.id);
+  }, []);
+
+  const load = useCallback(async () => {
+    if (!open || !definition?.id) return;
+    setLoading(true);
+    setError("");
+    try {
+      const items = await listWorkflowInstances(settings, definition.id);
+      setInstances(items);
+      setSelectedId((current) => (
+        items.some((item) => item.id === current)
+          ? current
+          : items[0]?.id ?? null
+      ));
+    } catch (loadError) {
+      setError(errorMessage(loadError));
+    } finally {
+      setLoading(false);
+    }
+  }, [definition?.id, open, settings]);
+
+  useEffect(() => {
+    if (!open) return;
+    setComment("");
+    setEvidence("");
+    void load();
+  }, [load, open]);
+
+  useEffect(() => {
+    if (
+      !open
+      || !canTransition
+      || !selected
+      || !currentStep
+      || currentStep.node_type !== "workflow.dataflow"
+      || !["queued", "retrying", "running"].includes(
+        String(currentStep.handoff.state ?? "")
+      )
+    ) {
+      return;
+    }
+    let stopped = false;
+    const poll = window.setInterval(() => {
+      void reconcileWorkflowInstance(settings, selected.id)
+        .then((instance) => {
+          if (!stopped) mergeInstance(instance);
+        })
+        .catch((pollError) => {
+          if (!stopped) setError(errorMessage(pollError));
+        });
+    }, 2500);
+    return () => {
+      stopped = true;
+      window.clearInterval(poll);
+    };
+  }, [
+    canTransition,
+    currentStep,
+    mergeInstance,
+    open,
+    selected,
+    settings
+  ]);
+
+  const start = async () => {
+    if (!definition?.id) return;
+    setWorking(true);
+    setError("");
+    try {
+      const instance = await startWorkflowInstance(settings, definition.id, {
+        idempotency_key: crypto.randomUUID(),
+        input: {}
+      });
+      mergeInstance(instance);
+    } catch (startError) {
+      setError(errorMessage(startError));
+    } finally {
+      setWorking(false);
+    }
+  };
+
+  const refreshSelected = async () => {
+    if (!selected) {
+      await load();
+      return;
+    }
+    setWorking(true);
+    setError("");
+    try {
+      const instance = canTransition
+        ? await reconcileWorkflowInstance(settings, selected.id)
+        : (await listWorkflowInstances(settings, definition?.id))
+          .find((item) => item.id === selected.id);
+      if (instance) mergeInstance(instance);
+      else await load();
+    } catch (refreshError) {
+      setError(errorMessage(refreshError));
+    } finally {
+      setWorking(false);
+    }
+  };
+
+  const performAction = async (action: WorkflowAction) => {
+    if (!selected || !currentStep) return;
+    setWorking(true);
+    setError("");
+    try {
+      const instance = await resolveWorkflowStep(
+        settings,
+        selected.id,
+        currentStep.id,
+        {
+          action,
+          comment: comment.trim() || null,
+          evidence: evidence
+            .split("\n")
+            .map((item) => item.trim())
+            .filter(Boolean)
+        }
+      );
+      mergeInstance(instance);
+      setComment("");
+      setEvidence("");
+    } catch (actionError) {
+      setError(errorMessage(actionError));
+    } finally {
+      setWorking(false);
+    }
+  };
+
+  const cancel = async () => {
+    if (!selected) return;
+    setWorking(true);
+    setError("");
+    try {
+      mergeInstance(await cancelWorkflowInstance(settings, selected.id));
+      setCancelOpen(false);
+    } catch (cancelError) {
+      setError(errorMessage(cancelError));
+    } finally {
+      setWorking(false);
+    }
+  };
+
+  const actionUrl = typeof currentStep?.handoff.action_url === "string"
+    ? currentStep.handoff.action_url
+    : "";
+
+  return (
+    <>
+      <Dialog
+        open={open}
+        title={`Runs${definition ? ` · ${definition.name}` : ""}`}
+        className="workflow-runs-dialog"
+        bodyClassName="workflow-runs-dialog-body"
+        onClose={onClose}
+        footer={<Button onClick={onClose}>Close</Button>}
+      >
+        <div className="workflow-runs-toolbar">
+          <span>
+            <strong>Workflow instances</strong>
+            <small>Revision-pinned runs and human handoffs</small>
+          </span>
+          <span>
+            <IconButton
+              label="Refresh runs"
+              icon={<RefreshCw size={16} />}
+              variant="ghost"
+              onClick={() => void refreshSelected()}
+              disabled={loading || working}
+            />
+            <Button
+              variant="primary"
+              onClick={() => void start()}
+              disabled={!canStart || working || definition?.status !== "active"}
+              disabledReason={
+                definition?.status !== "active"
+                  ? "Activate a definition revision before starting it."
+                  : undefined
+              }
+            >
+              <Play size={16} /> Start
+            </Button>
+          </span>
+        </div>
+        {error ? (
+          <DismissibleAlert tone="danger" resetKey={error}>
+            {error}
+          </DismissibleAlert>
+        ) : null}
+        <LoadingFrame loading={loading} className="workflow-runs-frame">
+          <div className="workflow-runs-layout">
+            <div className="workflow-run-list">
+              {instances.map((instance) => (
+                <button
+                  key={instance.id}
+                  type="button"
+                  className={instance.id === selected?.id ? "is-selected" : ""}
+                  onClick={() => {
+                    setSelectedId(instance.id);
+                    setComment("");
+                    setEvidence("");
+                  }}
+                >
+                  <span>
+                    <strong>{formatDateTime(instance.started_at)}</strong>
+                    <small>
+                      Revision {instance.definition_revision} · {instance.steps.length} steps
+                    </small>
+                  </span>
+                  <StatusBadge
+                    status={instance.status}
+                    label={instance.status}
+                  />
+                </button>
+              ))}
+              {!instances.length ? (
+                <div className="workflow-run-empty">No runs yet</div>
+              ) : null}
+            </div>
+            <div className="workflow-run-detail">
+              {selected ? (
+                <>
+                  <header>
+                    <span>
+                      <strong>{selected.definition_name}</strong>
+                      <small>
+                        Revision {selected.definition_revision} · {selected.definition_hash.slice(0, 12)}
+                      </small>
+                    </span>
+                    <span>
+                      <StatusBadge status={selected.status} label={selected.status} />
+                      {["running", "waiting"].includes(selected.status) ? (
+                        <IconButton
+                          label="Cancel workflow run"
+                          icon={<XCircle size={16} />}
+                          variant="danger"
+                          onClick={() => setCancelOpen(true)}
+                          disabled={!canTransition || working}
+                        />
+                      ) : null}
+                    </span>
+                  </header>
+                  {selected.error ? (
+                    <DismissibleAlert tone="danger" resetKey={selected.error}>
+                      {selected.error}
+                    </DismissibleAlert>
+                  ) : null}
+                  {currentStep ? (
+                    <section className="workflow-run-handoff">
+                      <div>
+                        <span>
+                          <strong>
+                            {String(
+                              currentStep.handoff.title
+                              ?? currentStep.handoff.kind
+                              ?? currentStep.node_type
+                            )}
+                          </strong>
+                          <small>
+                            Step {currentStep.sequence} · attempt {currentStep.attempt}
+                          </small>
+                        </span>
+                        <StatusBadge
+                          status={String(currentStep.handoff.state ?? currentStep.status)}
+                          label={String(currentStep.handoff.state ?? currentStep.status)}
+                        />
+                      </div>
+                      {typeof currentStep.handoff.message === "string" ? (
+                        <p>{currentStep.handoff.message}</p>
+                      ) : null}
+                      {typeof currentStep.handoff.instructions === "string"
+                        && currentStep.handoff.instructions ? (
+                          <p>{currentStep.handoff.instructions}</p>
+                        ) : null}
+                      {actionUrl ? (
+                        <a href={actionUrl}>
+                          Open linked Dataflow result <ExternalLink size={14} />
+                        </a>
+                      ) : null}
+                      {allowedActions.some((action) => action !== "cancel") ? (
+                        <div className="workflow-run-action-form">
+                          <FormField label="Comment">
+                            <textarea
+                              value={comment}
+                              onChange={(event) => setComment(event.target.value)}
+                              rows={2}
+                              disabled={!canTransition || working}
+                            />
+                          </FormField>
+                          <FormField
+                            label="Evidence references"
+                            help="Enter one durable evidence reference per line."
+                          >
+                            <textarea
+                              value={evidence}
+                              onChange={(event) => setEvidence(event.target.value)}
+                              rows={2}
+                              disabled={!canTransition || working}
+                            />
+                          </FormField>
+                          <div className="workflow-run-actions">
+                            {allowedActions
+                              .filter((action) => action !== "cancel")
+                              .map((action) => (
+                                <Button
+                                  key={action}
+                                  variant={
+                                    action === "reject"
+                                      ? "danger"
+                                      : action === "approve"
+                                        || action === "complete"
+                                        || action === "resume"
+                                        ? "primary"
+                                        : undefined
+                                  }
+                                  onClick={() => void performAction(action)}
+                                  disabled={!canTransition || working}
+                                >
+                                  {action === "retry" ? <RotateCcw size={15} /> : null}
+                                  {actionLabel(action)}
+                                </Button>
+                              ))}
+                          </div>
+                        </div>
+                      ) : null}
+                    </section>
+                  ) : null}
+                  <section className="workflow-run-history">
+                    <h3>Progress</h3>
+                    <div>
+                      {selected.steps.map((step) => (
+                        <span key={step.id}>
+                          <strong>{step.node_id}</strong>
+                          <small>
+                            {step.node_type} · attempt {step.attempt}
+                          </small>
+                          <StatusBadge status={step.status} label={step.status} />
+                        </span>
+                      ))}
+                    </div>
+                  </section>
+                  <section className="workflow-run-events">
+                    <h3>Evidence trail</h3>
+                    <div>
+                      {[...selected.events].reverse().map((event) => (
+                        <span key={event.id}>
+                          <strong>{event.kind}</strong>
+                          <small>
+                            {formatDateTime(event.created_at)}
+                            {event.actor_id ? ` · ${event.actor_id}` : ""}
+                          </small>
+                        </span>
+                      ))}
+                    </div>
+                  </section>
+                </>
+              ) : (
+                <div className="workflow-run-empty">
+                  Start a run to track its progress here.
+                </div>
+              )}
+            </div>
+          </div>
+        </LoadingFrame>
+      </Dialog>
+      <ConfirmDialog
+        open={cancelOpen}
+        title="Cancel workflow run"
+        message="Cancel this workflow instance and its active Dataflow run?"
+        confirmLabel="Cancel run"
+        tone="danger"
+        busy={working}
+        onCancel={() => setCancelOpen(false)}
+        onConfirm={() => void cancel()}
+      />
+    </>
+  );
+}
+
+function currentInstanceStep(
+  instance: WorkflowInstance | null
+): WorkflowInstanceStep | null {
+  if (!instance?.current_step_id) return null;
+  return instance.steps.find(
+    (step) => step.id === instance.current_step_id
+  ) ?? null;
+}
+
+function handoffActions(step: WorkflowInstanceStep | null): WorkflowAction[] {
+  const actions = step?.handoff.allowed_actions;
+  if (!Array.isArray(actions)) return [];
+  return actions.filter((action): action is WorkflowAction => (
+    typeof action === "string"
+    && [
+      "complete",
+      "approve",
+      "changes",
+      "reject",
+      "resume",
+      "retry",
+      "cancel"
+    ].includes(action)
+  ));
+}
+
+function actionLabel(action: WorkflowAction): string {
+  return {
+    complete: "Complete",
+    approve: "Approve",
+    changes: "Request changes",
+    reject: "Reject",
+    resume: "Resume",
+    retry: "Retry",
+    cancel: "Cancel"
+  }[action];
+}
+
+function formatDateTime(value: string): string {
+  return new Intl.DateTimeFormat(undefined, {
+    dateStyle: "medium",
+    timeStyle: "short"
+  }).format(new Date(value));
+}
+
+function errorMessage(error: unknown): string {
+  if (error instanceof Error) return error.message;
+  return "The Workflow request failed.";
+}

webui/src/styles/workflow.css

@@ -656,6 +656,255 @@
   padding: 7px 10px;
 }
 
+.workflow-runs-dialog {
+  width: min(1120px, calc(100vw - 32px));
+  height: min(760px, calc(100vh - 32px));
+}
+
+.workflow-runs-dialog-body {
+  display: flex;
+  min-height: 0;
+  flex-direction: column;
+  gap: 10px;
+  overflow: hidden;
+  padding: 0;
+}
+
+.workflow-runs-toolbar {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 12px;
+  flex: 0 0 auto;
+  min-height: 56px;
+  border-bottom: var(--border-line);
+  padding: 9px 12px;
+}
+
+.workflow-runs-toolbar > span {
+  display: flex;
+  align-items: center;
+  gap: 7px;
+}
+
+.workflow-runs-toolbar > span:first-child {
+  display: grid;
+  gap: 2px;
+}
+
+.workflow-runs-toolbar small {
+  color: var(--muted);
+  font-size: 11px;
+}
+
+.workflow-runs-frame,
+.workflow-runs-layout,
+.workflow-run-list,
+.workflow-run-detail {
+  min-width: 0;
+  min-height: 0;
+}
+
+.workflow-runs-frame {
+  flex: 1 1 auto;
+  overflow: hidden;
+}
+
+.workflow-runs-layout {
+  display: grid;
+  grid-template-columns: minmax(240px, 300px) minmax(0, 1fr);
+  height: 100%;
+  overflow: hidden;
+}
+
+.workflow-run-list {
+  overflow: auto;
+  border-right: var(--border-line);
+  background: var(--panel-soft);
+  padding: 6px;
+}
+
+.workflow-run-list > button {
+  display: grid;
+  grid-template-columns: minmax(0, 1fr) auto;
+  align-items: center;
+  gap: 8px;
+  width: 100%;
+  min-height: 54px;
+  border: 0;
+  border-radius: var(--radius-sm);
+  background: transparent;
+  color: var(--text);
+  cursor: pointer;
+  padding: 8px 9px;
+  text-align: left;
+}
+
+.workflow-run-list > button:hover,
+.workflow-run-list > button:focus-visible {
+  background: var(--primary-soft);
+  outline: none;
+}
+
+.workflow-run-list > button.is-selected {
+  background: var(--primary-soft-strong);
+  box-shadow: inset 3px 0 0 var(--accent);
+}
+
+.workflow-run-list strong,
+.workflow-run-list small {
+  display: block;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.workflow-run-list strong {
+  color: var(--text-strong);
+  font-size: 12px;
+}
+
+.workflow-run-list small {
+  margin-top: 4px;
+  color: var(--muted);
+  font-size: 10px;
+}
+
+.workflow-run-detail {
+  display: flex;
+  flex-direction: column;
+  overflow: auto;
+}
+
+.workflow-run-detail > header,
+.workflow-run-handoff > div:first-child {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 10px;
+}
+
+.workflow-run-detail > header {
+  position: sticky;
+  z-index: 2;
+  top: 0;
+  min-height: 56px;
+  border-bottom: var(--border-line);
+  background: var(--panel);
+  padding: 9px 12px;
+}
+
+.workflow-run-detail > header > span {
+  display: flex;
+  align-items: center;
+  gap: 7px;
+}
+
+.workflow-run-detail > header > span:first-child {
+  display: grid;
+  min-width: 0;
+  gap: 2px;
+}
+
+.workflow-run-detail > header strong,
+.workflow-run-detail > header small {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.workflow-run-detail > header small {
+  color: var(--muted);
+  font-size: 10px;
+}
+
+.workflow-run-handoff,
+.workflow-run-history,
+.workflow-run-events {
+  display: grid;
+  gap: 10px;
+  border-bottom: var(--border-line);
+  padding: 12px;
+}
+
+.workflow-run-handoff p {
+  margin: 0;
+  color: var(--muted);
+  font-size: 12px;
+  line-height: 1.45;
+}
+
+.workflow-run-handoff a {
+  display: inline-flex;
+  align-items: center;
+  gap: 5px;
+  width: fit-content;
+  color: var(--accent);
+  font-size: 12px;
+}
+
+.workflow-run-action-form {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 10px;
+}
+
+.workflow-run-action-form textarea {
+  width: 100%;
+  resize: vertical;
+}
+
+.workflow-run-actions {
+  display: flex;
+  grid-column: 1 / -1;
+  flex-wrap: wrap;
+  gap: 7px;
+}
+
+.workflow-run-actions .btn {
+  display: inline-flex;
+  align-items: center;
+  gap: 5px;
+}
+
+.workflow-run-history h3,
+.workflow-run-events h3 {
+  margin: 0;
+  color: var(--text-strong);
+  font-size: 12px;
+}
+
+.workflow-run-history > div,
+.workflow-run-events > div {
+  display: grid;
+}
+
+.workflow-run-history > div > span,
+.workflow-run-events > div > span {
+  display: grid;
+  grid-template-columns: minmax(0, 1fr) minmax(160px, auto) auto;
+  align-items: center;
+  gap: 9px;
+  min-height: 38px;
+  border-top: var(--border-line);
+  padding: 6px 2px;
+}
+
+.workflow-run-history small,
+.workflow-run-events small {
+  color: var(--muted);
+  font-size: 10px;
+}
+
+.workflow-run-empty {
+  display: grid;
+  min-height: 120px;
+  place-items: center;
+  color: var(--muted);
+  font-size: 12px;
+  text-align: center;
+}
+
 @media (max-width: 1180px) {
   .workflow-shell {
     grid-template-columns: 240px minmax(0, 1fr);
@@ -749,4 +998,28 @@
   .workflow-palette-items button {
     min-width: 128px;
   }
+
+  .workflow-runs-layout {
+    grid-template-columns: 1fr;
+    grid-template-rows: minmax(120px, 28%) minmax(0, 1fr);
+  }
+
+  .workflow-run-list {
+    border-right: 0;
+    border-bottom: var(--border-line);
+  }
+
+  .workflow-run-action-form {
+    grid-template-columns: 1fr;
+  }
+
+  .workflow-run-history > div > span,
+  .workflow-run-events > div > span {
+    grid-template-columns: minmax(0, 1fr) auto;
+  }
+
+  .workflow-run-history > div > span small,
+  .workflow-run-events > div > span small {
+    grid-column: 1 / -1;
+  }
 }