package agenttask

import (
	"context"
	"fmt"
	"reflect"

	"iop/packages/go/agentguard"
	"iop/packages/go/agentpolicy"
)

func (m *Manager) runWork(
	ctx context.Context,
	projectID ProjectID,
	workID WorkUnitID,
) error {
	for {
		project, work, err := m.loadWork(ctx, projectID, workID)
		if err != nil {
			return err
		}
		switch work.State {
		case WorkStateReviewing:
			if work.Submission == nil {
				m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
					Code:    BlockerArtifactMismatch,
					Message: "reviewing work has no durable submission identity",
				})
				return nil
			}
			rework, reviewErr := m.reviewSubmission(ctx, project, work, *work.Submission)
			if reviewErr != nil || !rework {
				return reviewErr
			}
			continue
		case WorkStateReady:
		default:
			return nil
		}

		if err := m.changeWork(ctx, projectID, workID, func(work *WorkRecord) error {
			return transitionWork(work, WorkStatePreparing)
		}); err != nil {
			return err
		}
		project, work, err = m.loadWork(ctx, projectID, workID)
		if err != nil {
			return err
		}
		target, err := m.selectTarget(ctx, project, work)
		if err != nil {
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code: BlockerSelectionFailed, Message: err.Error(), Retryable: true,
			})
			return nil
		}
		if err := validateTarget(project, target); err != nil {
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code: BlockerInvalidIdentity, Message: err.Error(),
			})
			return nil
		}
		isolation, err := m.isolation.Prepare(ctx, IsolationRequest{
			Project: project, Work: work, Target: target,
			IdempotencyKey: dispatchKey(projectID, workID, work.Attempt) + "/isolation",
		})
		if err != nil {
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code: BlockerIsolationFailed, Message: err.Error(), Retryable: true,
			})
			return nil
		}
		admissionRequest, isolationIdentity, err := validatePreparedIsolation(project, work, target, isolation)
		if err != nil {
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code: BlockerIsolationFailed, Message: err.Error(),
			})
			return nil
		}
		admission := agentguard.Admit(admissionRequest)
		if !admission.Allowed() {
			detail := "workspace admission denied"
			if admission.Blocker != nil {
				detail = string(admission.Blocker.Code) + ": " + admission.Blocker.Message
			}
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code: BlockerAdmissionFailed, Message: detail,
			})
			return nil
		}
		lease, err := m.scheduler.Acquire(ctx, DispatchCandidate{
			ProjectID: projectID, WorkspaceID: project.WorkspaceID,
			WorkUnitID: workID, AttemptID: work.AttemptID, Target: target,
		})
		if err != nil {
			if ctx.Err() != nil {
				_ = m.changeWork(context.WithoutCancel(ctx), projectID, workID, func(work *WorkRecord) error {
					return transitionWork(work, WorkStateReady)
				})
				return ctx.Err()
			}
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code: BlockerProviderCapacity, Message: err.Error(), Retryable: true,
			})
			return nil
		}
		err = m.changeWork(ctx, projectID, workID, func(work *WorkRecord) error {
			if err := transitionWork(work, WorkStateDispatching); err != nil {
				return err
			}
			work.Target = &target
			work.Isolation = &isolationIdentity
			if work.Locators == nil {
				work.Locators = make(map[LocatorKind]LocatorRecord)
			}
			work.Locators[LocatorOverlay] = locatorForIsolation(project, *work, isolationIdentity)
			return nil
		})
		if err != nil {
			lease.Release()
			return err
		}
		project, work, err = m.loadWork(ctx, projectID, workID)
		if err != nil {
			lease.Release()
			return err
		}
		var cmdID CommandID
		var wfRev WorkflowRevision
		if project.Intent != nil {
			cmdID = project.Intent.CommandID
			wfRev = project.Intent.WorkflowRevision
		}
		m.emit(ctx, Event{
			Type: EventDispatchStarted, ProjectID: projectID, WorkspaceID: project.WorkspaceID,
			WorkUnitID: workID, CommandID: cmdID, WorkflowRevision: wfRev, AttemptID: work.AttemptID, Ordinal: work.DispatchOrdinal,
			State: work.State, ProviderID: target.ProviderID, ProfileID: target.ProfileID,
			WriteSetKind: work.Unit.WriteSetKind, IsolationMode: work.Unit.IsolationMode,
		})
		var invocation ProviderInvocation
		var launch ProviderLaunch
		confinementBinding := isolation.Confinement.Binding()
		dispatchRequest := DispatchRequest{
			Project: project, Work: work, Target: target, AdmissionRequest: admissionRequest,
			Permit: admission.Permit, Workspace: *admission.Workspace,
			Confinement:    isolation.Confinement,
			IdempotencyKey: dispatchKey(projectID, workID, work.Attempt),
		}
		validation, invokeErr := agentguard.Invoke(
			ctx,
			admission.Permit,
			admissionRequest,
			func(invokeCtx context.Context, workspace agentguard.CanonicalWorkspace) error {
				if workspace.ConfinementRevision != isolation.Confinement.Revision() {
					return fmt.Errorf(
						"agenttask: permit confinement revision does not match the executable proof",
					)
				}
				if err := isolation.Confinement.Validate(confinementBinding); err != nil {
					return fmt.Errorf(
						"agenttask: executable confinement proof became invalid before invocation: %w",
						err,
					)
				}
				dispatchRequest.Workspace = workspace
				prepared, err := m.invoker.Prepare(invokeCtx, dispatchRequest)
				if err != nil {
					return err
				}
				if prepared == nil {
					return fmt.Errorf("agenttask: provider returned a nil launch plan")
				}
				launch = prepared
				command := launch.Command()
				started, err := isolation.Confinement.Start(invokeCtx, command)
				if err != nil {
					return fmt.Errorf("agenttask: start provider through executable confinement: %w", err)
				}
				if err := validateStartedConfinement(started); err != nil {
					if started != nil {
						_ = started.Abort()
					}
					return err
				}
				invocation, err = launch.BindStarted(started)
				if err != nil {
					_ = started.Abort()
					return fmt.Errorf("agenttask: bind confined provider child: %w", err)
				}
				if invocation == nil {
					_ = started.Abort()
					return fmt.Errorf("agenttask: provider bound a nil invocation handle")
				}
				return nil
			},
		)
		if !validation.Allowed() {
			lease.Release()
			detail := "admission permit became invalid before invocation"
			if validation.Blocker != nil {
				detail = string(validation.Blocker.Code) + ": " + validation.Blocker.Message
			}
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code: BlockerAdmissionFailed, Message: detail,
			})
			return nil
		}
		if invokeErr != nil {
			lease.Release()
			if ctx.Err() != nil {
				return ctx.Err()
			}
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code: BlockerInvocationFailed, Message: "provider launch failed before a normalized invocation was available", Retryable: true,
			})
			return nil
		}
		if launch == nil || invocation == nil {
			lease.Release()
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code: BlockerInvocationFailed, Message: "provider launch did not bind an invocation handle",
			})
			return nil
		}
		invocationLocators := invocation.Locators()
		if err := validateInvocationLocators(project, work, invocationLocators); err != nil {
			_ = invocation.Cancel(context.WithoutCancel(ctx))
			lease.Release()
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code: BlockerStaleCheckpoint, Message: err.Error(),
			})
			return nil
		}
		if err := m.changeWork(ctx, projectID, workID, func(work *WorkRecord) error {
			for _, locator := range invocationLocators {
				work.Locators[locator.Kind] = locator
			}
			return nil
		}); err != nil {
			_ = invocation.Cancel(context.WithoutCancel(ctx))
			lease.Release()
			return err
		}
		submission, invokeErr := invocation.Wait(ctx)
		lease.Release()
		if invokeErr != nil {
			if ctx.Err() != nil {
				return ctx.Err()
			}
			handled, continueWork, continuationErr := m.continueAfterInvocationFailure(
				ctx, project, work, target, invocation,
			)
			if continuationErr != nil {
				return continuationErr
			}
			if handled {
				if continueWork {
					continue
				}
				return nil
			}
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code: BlockerInvocationFailed, Message: "provider invocation failed without a normalized failure observation", Retryable: true,
			})
			return nil
		}
		project, work, err = m.loadWork(ctx, projectID, workID)
		if err != nil {
			return err
		}
		if err := validateSubmission(project, work, submission); err != nil {
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code: BlockerArtifactMismatch, Message: err.Error(),
			})
			return nil
		}
		if !submission.Ready {
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, Blocker{
				Code:    BlockerSubmissionIncomplete,
				Message: "worker submission did not pass the provider-neutral completeness gate",
			})
			return nil
		}
		if blocker := m.gateSubmissionEvidence(ctx, project, work, submission); blocker != nil {
			m.blockWork(ctx, projectID, workID, WorkStateBlocked, *blocker)
			return nil
		}
		if err := m.changeWork(ctx, projectID, workID, func(work *WorkRecord) error {
			if err := transitionWork(work, WorkStateSubmitted); err != nil {
				return err
			}
			work.Submission = &submission
			for _, locator := range submission.Locators {
				work.Locators[locator.Kind] = locator
			}
			resetFailure(work, FailureStageDispatch)
			work.ContinuationTarget = nil
			return nil
		}); err != nil {
			return err
		}
		m.emit(ctx, Event{
			Type: EventSubmissionAccepted, ProjectID: projectID, WorkspaceID: project.WorkspaceID,
			WorkUnitID: workID, CommandID: cmdID, WorkflowRevision: wfRev, AttemptID: work.AttemptID, Ordinal: work.DispatchOrdinal,
			Detail: string(submission.ArtifactID),
		})
		if err := m.changeWork(ctx, projectID, workID, func(work *WorkRecord) error {
			return transitionWork(work, WorkStateReviewing)
		}); err != nil {
			return err
		}
		project, work, err = m.loadWork(ctx, projectID, workID)
		if err != nil {
			return err
		}
		rework, err := m.reviewSubmission(ctx, project, work, submission)
		if err != nil || !rework {
			return err
		}
	}
}

// selectTarget preserves a policy-authorized continuation target across a
// crash or pre-invocation retry. New work still goes through the ordinary
// selector; no continuation target is inferred from a previous failure.
func (m *Manager) selectTarget(
	ctx context.Context,
	project ProjectRecord,
	work WorkRecord,
) (ExecutionTarget, error) {
	if work.ContinuationTarget != nil {
		return *work.ContinuationTarget, nil
	}
	return m.selector.Select(ctx, SelectionRequest{Project: project, Work: work})
}

func (m *Manager) continueAfterInvocationFailure(
	ctx context.Context,
	project ProjectRecord,
	work WorkRecord,
	current ExecutionTarget,
	invocation ProviderInvocation,
) (handled bool, continueWork bool, err error) {
	observed, ok := invocation.(FailureObservedInvocation)
	if !ok {
		return false, false, nil
	}
	observation := agentpolicy.SanitizeAttemptObservation(
		observed.FailureObservation(),
		m.clock.Now(),
	)
	if !observationMatchesTarget(observation, current) {
		observation.Quota = agentpolicy.CorruptQuotaObservation()
	}
	source, ok := m.selector.(FailureContinuationPolicySource)
	if !ok {
		return m.persistContinuation(
			ctx,
			project,
			work,
			current,
			observation,
			agentpolicy.ContinuationBlock,
			nil,
			Blocker{
				Code:    BlockerFailurePolicyUnavailable,
				Message: "no declared failure continuation policy is available",
			},
		)
	}
	policy, policyErr := source.ContinuationPolicy(ctx, FailureContinuationPolicyRequest{
		Project:       project,
		Work:          work,
		CurrentTarget: current,
		Observation:   observation,
	})
	if policyErr != nil {
		return m.persistContinuation(
			ctx,
			project,
			work,
			current,
			observation,
			agentpolicy.ContinuationBlock,
			nil,
			Blocker{
				Code:    BlockerFailurePolicyDenied,
				Message: "failure continuation policy rejected the observation",
			},
		)
	}
	request, candidateTargets, buildErr := m.continuationRequest(
		project,
		work,
		current,
		observation,
		policy,
	)
	if buildErr != nil {
		return m.persistContinuation(
			ctx,
			project,
			work,
			current,
			observation,
			agentpolicy.ContinuationBlock,
			nil,
			Blocker{
				Code:    BlockerFailurePolicyDenied,
				Message: "failure continuation policy inputs are invalid",
			},
		)
	}
	decision, decisionErr := agentpolicy.DecideContinuation(request)
	if decisionErr != nil {
		return m.persistContinuation(
			ctx,
			project,
			work,
			current,
			observation,
			agentpolicy.ContinuationBlock,
			nil,
			Blocker{
				Code:    BlockerFailurePolicyDenied,
				Message: "common failure continuation policy rejected its inputs",
			},
		)
	}
	switch decision.Action {
	case agentpolicy.ContinuationBlock:
		if decision.Blocker == "" {
			return m.persistContinuation(
				ctx,
				project,
				work,
				current,
				observation,
				agentpolicy.ContinuationBlock,
				nil,
				Blocker{
					Code:    BlockerFailurePolicyDenied,
					Message: "failure continuation policy returned an invalid block decision",
				},
			)
		}
		return m.persistContinuation(
			ctx,
			project,
			work,
			current,
			observation,
			decision.Action,
			nil,
			blockerFromContinuation(decision.Blocker),
		)
	case agentpolicy.ContinuationRetry:
		if !targetMatchesIdentity(current, decision.Target) {
			return m.persistContinuation(
				ctx,
				project,
				work,
				current,
				observation,
				agentpolicy.ContinuationBlock,
				nil,
				Blocker{
					Code:    BlockerFailurePolicyDenied,
					Message: "failure continuation policy returned an invalid next target",
				},
			)
		}
		return m.persistContinuation(
			ctx,
			project,
			work,
			current,
			observation,
			decision.Action,
			&current,
			Blocker{},
		)
	case agentpolicy.ContinuationFailover:
		next, exists := candidateTargets[decision.Target]
		if !exists || sameExecutionTarget(next, current) {
			return m.persistContinuation(
				ctx,
				project,
				work,
				current,
				observation,
				agentpolicy.ContinuationBlock,
				nil,
				Blocker{
					Code:    BlockerFailurePolicyDenied,
					Message: "common failure policy selected an unknown failover target",
				},
			)
		}
		return m.persistContinuation(
			ctx,
			project,
			work,
			current,
			observation,
			decision.Action,
			&next,
			Blocker{},
		)
	default:
		return m.persistContinuation(
			ctx,
			project,
			work,
			current,
			observation,
			agentpolicy.ContinuationBlock,
			nil,
			Blocker{
				Code:    BlockerFailurePolicyDenied,
				Message: "failure continuation policy returned an unsupported action",
			},
		)
	}
}

func (m *Manager) continuationRequest(
	project ProjectRecord,
	work WorkRecord,
	current ExecutionTarget,
	observation agentpolicy.AttemptObservation,
	source FailureContinuationPolicy,
) (agentpolicy.ContinuationRequest, map[agentpolicy.TargetIdentity]ExecutionTarget, error) {
	currentIdentity := executionTargetIdentity(current)
	used := make([]agentpolicy.TargetIdentity, 0, len(work.AttemptObservations))
	seenUsed := make(map[agentpolicy.TargetIdentity]struct{}, len(work.AttemptObservations))
	for _, record := range work.AttemptObservations {
		identity := executionTargetIdentity(record.Target)
		if _, duplicate := seenUsed[identity]; duplicate {
			continue
		}
		seenUsed[identity] = struct{}{}
		used = append(used, identity)
	}

	candidates := make([]agentpolicy.ContinuationCandidate, 0, len(source.Candidates))
	candidateTargets := make(map[agentpolicy.TargetIdentity]ExecutionTarget, len(source.Candidates))
	for _, candidate := range source.Candidates {
		if err := validateTarget(project, candidate.Target); err != nil {
			return agentpolicy.ContinuationRequest{}, nil, err
		}
		identity := executionTargetIdentity(candidate.Target)
		if _, duplicate := candidateTargets[identity]; duplicate {
			return agentpolicy.ContinuationRequest{}, nil, fmt.Errorf(
				"agenttask: continuation policy repeats a candidate target",
			)
		}
		quota := agentpolicy.SanitizeQuotaObservation(candidate.Quota)
		if quota.Validity != agentpolicy.ObservationCorrupt &&
			(quota.Adapter != candidate.Target.ProviderID ||
				quota.Target != candidate.Target.ProfileID) {
			quota = agentpolicy.CorruptQuotaObservation()
		}
		candidateTargets[identity] = candidate.Target
		candidates = append(candidates, agentpolicy.ContinuationCandidate{
			Target:   identity,
			Eligible: candidate.Eligible,
			Quota:    quota,
		})
	}
	return agentpolicy.ContinuationRequest{
		Policy:      source.Policy,
		Current:     currentIdentity,
		Candidates:  candidates,
		Used:        used,
		Budget:      m.pendingFailureBudget(work),
		Observation: observation,
	}, candidateTargets, nil
}

func (m *Manager) persistContinuation(
	ctx context.Context,
	project ProjectRecord,
	failedWork WorkRecord,
	current ExecutionTarget,
	observation agentpolicy.AttemptObservation,
	action agentpolicy.ContinuationAction,
	next *ExecutionTarget,
	blocker Blocker,
) (handled bool, continueWork bool, err error) {
	var outcomeBlocker Blocker
	var nextAttempt AttemptID
	continued := false
	err = m.changeWork(ctx, project.ProjectID, failedWork.Unit.ID, func(work *WorkRecord) error {
		if work.AttemptID != failedWork.AttemptID || work.State != WorkStateDispatching {
			return fmt.Errorf("agenttask: failed work changed before continuation was persisted")
		}
		if err := appendAttemptObservation(work, current, observation); err != nil {
			return err
		}
		if action == agentpolicy.ContinuationBlock {
			outcomeBlocker = m.recordFailure(work, FailureStageDispatch, blocker)
			if err := transitionWork(work, WorkStateBlocked); err != nil {
				return err
			}
			work.Blocker = &outcomeBlocker
			return nil
		}
		outcomeBlocker = m.recordFailure(work, FailureStageDispatch, Blocker{
			Code:      BlockerInvocationFailed,
			Message:   "provider execution failed; continuation was policy-authorized",
			Retryable: true,
		})
		if outcomeBlocker.Code == BlockerFailureBudgetExhausted {
			if err := transitionWork(work, WorkStateBlocked); err != nil {
				return err
			}
			work.Blocker = &outcomeBlocker
			return nil
		}
		if next == nil {
			return fmt.Errorf("agenttask: continuation has no next target")
		}
		if err := transitionWork(work, WorkStateReady); err != nil {
			return err
		}
		work.Attempt++
		work.AttemptID = attemptID(work.Unit.ID, work.Attempt)
		target := *next
		work.Target = nil
		work.ContinuationTarget = &target
		work.Isolation = nil
		work.Submission = nil
		work.Review = nil
		work.ChangeSet = nil
		work.Integration = nil
		work.Locators = make(map[LocatorKind]LocatorRecord)
		work.Blocker = nil
		nextAttempt = work.AttemptID
		continued = true
		return nil
	})
	if err != nil {
		return true, false, err
	}
	if continued {
		var commandID CommandID
		var workflowRevision WorkflowRevision
		if project.Intent != nil {
			commandID = project.Intent.CommandID
			workflowRevision = project.Intent.WorkflowRevision
		}
		m.emit(ctx, Event{
			Type: EventFollowup, ProjectID: project.ProjectID, WorkspaceID: project.WorkspaceID,
			WorkUnitID: failedWork.Unit.ID, CommandID: commandID, WorkflowRevision: workflowRevision,
			AttemptID: nextAttempt, Ordinal: failedWork.DispatchOrdinal, Detail: string(action),
		})
		return true, true, nil
	}
	m.emit(ctx, Event{
		Type: EventBlocked, ProjectID: project.ProjectID, WorkspaceID: project.WorkspaceID,
		WorkUnitID: failedWork.Unit.ID, AttemptID: failedWork.AttemptID,
		Ordinal: failedWork.DispatchOrdinal, State: WorkStateBlocked, Detail: string(outcomeBlocker.Code),
	})
	return true, false, nil
}

func (m *Manager) pendingFailureBudget(work WorkRecord) agentpolicy.FailureBudget {
	budget := work.FailureBudgets[FailureStageDispatch]
	limit := budget.Limit
	if limit == 0 {
		limit = m.config.MaxFailureAttempts
	}
	used := budget.Consecutive
	if used < limit {
		used++
	}
	return agentpolicy.FailureBudget{Used: used, Limit: limit}
}

func appendAttemptObservation(
	work *WorkRecord,
	target ExecutionTarget,
	observation agentpolicy.AttemptObservation,
) error {
	record := AttemptObservationRecord{
		AttemptID:   work.AttemptID,
		Target:      target,
		Observation: observation.Clone(),
	}
	for _, existing := range work.AttemptObservations {
		if existing.AttemptID != record.AttemptID {
			continue
		}
		if reflect.DeepEqual(existing, record) {
			return nil
		}
		return fmt.Errorf("agenttask: a different failure observation already exists for this attempt")
	}
	work.AttemptObservations = append(work.AttemptObservations, record)
	return nil
}

func observationMatchesTarget(
	observation agentpolicy.AttemptObservation,
	target ExecutionTarget,
) bool {
	if observation.Quota.Validity == agentpolicy.ObservationCorrupt {
		return true
	}
	return observation.Quota.Adapter == target.ProviderID &&
		observation.Quota.Target == target.ProfileID
}

func targetMatchesIdentity(
	target ExecutionTarget,
	identity agentpolicy.TargetIdentity,
) bool {
	return target.ProviderID == identity.ProviderID &&
		target.ModelID == identity.ModelID &&
		target.ProfileID == identity.ProfileID &&
		target.ProfileRevision == identity.ProfileRevision
}

func executionTargetIdentity(target ExecutionTarget) agentpolicy.TargetIdentity {
	return agentpolicy.TargetIdentity{
		ProviderID:      target.ProviderID,
		ModelID:         target.ModelID,
		ProfileID:       target.ProfileID,
		ProfileRevision: target.ProfileRevision,
	}
}

func sameExecutionTarget(left, right ExecutionTarget) bool {
	return left.ProviderID == right.ProviderID &&
		left.ModelID == right.ModelID &&
		left.ProfileID == right.ProfileID &&
		left.ProfileRevision == right.ProfileRevision &&
		left.ConfigRevision == right.ConfigRevision &&
		left.Capacity == right.Capacity
}

func blockerFromContinuation(code agentpolicy.ContinuationBlockerCode) Blocker {
	switch code {
	case agentpolicy.ContinuationBlockerUnknownQuota:
		return Blocker{Code: BlockerFailureObservationUnknown, Message: "quota observation is unknown"}
	case agentpolicy.ContinuationBlockerStaleObservation:
		return Blocker{Code: BlockerFailureObservationStale, Message: "quota observation is stale"}
	case agentpolicy.ContinuationBlockerCorruptObservation:
		return Blocker{Code: BlockerFailureObservationCorrupt, Message: "quota observation is corrupt"}
	case agentpolicy.ContinuationBlockerUnknownFailure:
		return Blocker{Code: BlockerFailureUnknown, Message: "runtime failure is unknown"}
	case agentpolicy.ContinuationBlockerBudgetExhausted:
		return Blocker{Code: BlockerFailureBudgetExhausted, Message: "failure budget is exhausted"}
	case agentpolicy.ContinuationBlockerNoAlternate:
		return Blocker{Code: BlockerNoEligibleFailover, Message: "no eligible unused failover target remains"}
	default:
		return Blocker{Code: BlockerFailurePolicyDenied, Message: "failure is not declared by policy"}
	}
}

func validateStartedConfinement(started StartedConfinement) error {
	if started == nil {
		return fmt.Errorf("agenttask: executable confinement returned a nil started handle")
	}
	if started.Child() == nil {
		return fmt.Errorf("agenttask: executable confinement returned a started handle without a child")
	}
	if started.Stdin() == nil || started.Stdout() == nil || started.Stderr() == nil {
		return fmt.Errorf("agenttask: executable confinement returned incomplete child I/O")
	}
	return nil
}

func validateInvocationLocators(
	project ProjectRecord,
	work WorkRecord,
	locators []LocatorRecord,
) error {
	if len(locators) == 0 {
		return fmt.Errorf("agenttask: provider invocation returned no durable process or session locator")
	}
	seen := make(map[LocatorKind]struct{}, len(locators))
	for _, locator := range locators {
		if locator.Kind != LocatorProcess && locator.Kind != LocatorSession {
			return fmt.Errorf("agenttask: provider returned unsupported %q invocation locator", locator.Kind)
		}
		if _, duplicate := seen[locator.Kind]; duplicate {
			return fmt.Errorf("agenttask: provider returned duplicate %q invocation locator", locator.Kind)
		}
		seen[locator.Kind] = struct{}{}
		if err := validateLocator(project, work, locator); err != nil {
			return err
		}
		if existing, ok := work.Locators[locator.Kind]; ok &&
			!reflect.DeepEqual(existing, locator) {
			return fmt.Errorf("agenttask: provider replaced the durable %q locator", locator.Kind)
		}
	}
	return nil
}

func validateTarget(project ProjectRecord, target ExecutionTarget) error {
	for field, value := range map[string]string{
		"provider":         target.ProviderID,
		"model":            target.ModelID,
		"profile":          target.ProfileID,
		"profile_revision": target.ProfileRevision,
	} {
		if err := validateIdentity(field, value); err != nil {
			return err
		}
	}
	if project.Intent == nil || target.ConfigRevision != project.Intent.ConfigRevision {
		return fmt.Errorf("agenttask: selected target config revision does not match manual start")
	}
	if target.Capacity <= 0 {
		return fmt.Errorf("agenttask: selected target capacity must be positive")
	}
	return nil
}

func validatePreparedIsolation(
	project ProjectRecord,
	work WorkRecord,
	target ExecutionTarget,
	prepared PreparedIsolation,
) (agentguard.AdmissionRequest, IsolationIdentity, error) {
	if prepared.Grant == nil || prepared.Descriptor == nil ||
		prepared.Confinement == nil {
		return agentguard.AdmissionRequest{}, IsolationIdentity{},
			fmt.Errorf("agenttask: isolation backend returned incomplete strict ports")
	}
	if project.Intent == nil {
		return agentguard.AdmissionRequest{}, IsolationIdentity{},
			fmt.Errorf("agenttask: project has no manual start intent")
	}
	if prepared.Grant.ProjectID != string(project.ProjectID) ||
		prepared.Grant.WorkspaceID != string(project.WorkspaceID) ||
		prepared.Grant.Revision != string(project.Intent.GrantRevision) {
		return agentguard.AdmissionRequest{}, IsolationIdentity{},
			fmt.Errorf("agenttask: workspace grant identity or revision mismatch")
	}
	if prepared.Descriptor.Mode != work.Unit.IsolationMode {
		return agentguard.AdmissionRequest{}, IsolationIdentity{},
			fmt.Errorf("agenttask: isolation mode differs from the workflow request")
	}
	if prepared.Profile.ProviderID != target.ProviderID ||
		prepared.Profile.ModelID != target.ModelID ||
		prepared.Profile.ProfileID != target.ProfileID ||
		prepared.Profile.Revision != target.ProfileRevision {
		return agentguard.AdmissionRequest{}, IsolationIdentity{},
			fmt.Errorf("agenttask: admitted provider profile differs from selected target")
	}
	expectedConfinement := ConfinementBinding{
		Revision:           prepared.Descriptor.ConfinementRevision,
		IsolationID:        prepared.Descriptor.ID,
		IsolationRevision:  prepared.Descriptor.Revision,
		PinnedBaseRevision: prepared.Descriptor.PinnedBaseRevision,
		ConfigRevision:     string(project.Intent.ConfigRevision),
		GrantRevision:      prepared.Grant.Revision,
		ProfileRevision:    prepared.Profile.Revision,
		BaseRoot:           prepared.Descriptor.BaseRoot,
		TaskRoot:           prepared.Descriptor.TaskRoot,
		WorkingDir:         prepared.Descriptor.WorkingDir,
		WritableRoots:      append([]string(nil), prepared.Descriptor.WritableRoots...),
	}
	actualConfinement := prepared.Confinement.Binding()
	expectedConfinement.RuntimeRoot = actualConfinement.RuntimeRoot
	expectedConfinement.SnapshotRoot = actualConfinement.SnapshotRoot
	if prepared.Confinement.Revision() != expectedConfinement.Revision {
		return agentguard.AdmissionRequest{}, IsolationIdentity{},
			fmt.Errorf("agenttask: confinement proof revision differs from the isolation descriptor")
	}
	if err := prepared.Confinement.Validate(expectedConfinement); err != nil {
		return agentguard.AdmissionRequest{}, IsolationIdentity{},
			fmt.Errorf("agenttask: invalid executable confinement proof: %w", err)
	}
	identity := IsolationIdentity{
		ID: prepared.Descriptor.ID, Revision: prepared.Descriptor.Revision,
		Mode: prepared.Descriptor.Mode, PinnedBaseRevision: prepared.Descriptor.PinnedBaseRevision,
		TaskRoot: prepared.Descriptor.TaskRoot,
	}
	for field, value := range map[string]string{
		"isolation":            identity.ID,
		"isolation_revision":   identity.Revision,
		"pinned_base_revision": identity.PinnedBaseRevision,
	} {
		if err := validateIdentity(field, value); err != nil {
			return agentguard.AdmissionRequest{}, IsolationIdentity{}, err
		}
	}
	return agentguard.AdmissionRequest{
		Grant: prepared.Grant, Isolation: prepared.Descriptor, Profile: prepared.Profile,
	}, identity, nil
}

func validateSubmission(project ProjectRecord, work WorkRecord, submission Submission) error {
	if submission.ProjectID != project.ProjectID || submission.WorkUnitID != work.Unit.ID ||
		submission.AttemptID != work.AttemptID {
		return fmt.Errorf("agenttask: submission durable identity mismatch")
	}
	if err := validateIdentity("artifact", string(submission.ArtifactID)); err != nil {
		return err
	}
	seen := make(map[LocatorKind]struct{}, len(submission.Locators))
	for _, locator := range submission.Locators {
		if locator.Kind != LocatorProcess && locator.Kind != LocatorSession {
			return fmt.Errorf("agenttask: provider returned unsupported %q submission locator", locator.Kind)
		}
		if _, duplicate := seen[locator.Kind]; duplicate {
			return fmt.Errorf("agenttask: provider returned duplicate %q submission locator", locator.Kind)
		}
		seen[locator.Kind] = struct{}{}
		if err := validateLocator(project, work, locator); err != nil {
			return err
		}
		if existing, ok := work.Locators[locator.Kind]; ok &&
			!reflect.DeepEqual(existing, locator) {
			return fmt.Errorf("agenttask: submission replaced the durable %q locator", locator.Kind)
		}
	}
	return nil
}

func (m *Manager) loadWork(
	ctx context.Context,
	projectID ProjectID,
	workID WorkUnitID,
) (ProjectRecord, WorkRecord, error) {
	state, err := m.load(ctx)
	if err != nil {
		return ProjectRecord{}, WorkRecord{}, err
	}
	project, ok := state.Projects[projectID]
	if !ok {
		return ProjectRecord{}, WorkRecord{}, fmt.Errorf("agenttask: project %q disappeared", projectID)
	}
	work, ok := project.Works[workID]
	if !ok {
		return ProjectRecord{}, WorkRecord{}, fmt.Errorf("agenttask: work %q disappeared", workID)
	}
	return project, work, nil
}

func (m *Manager) changeWork(
	ctx context.Context,
	projectID ProjectID,
	workID WorkUnitID,
	change func(*WorkRecord) error,
) error {
	return m.mutate(ctx, func(state *ManagerState) error {
		project, ok := state.Projects[projectID]
		if !ok {
			return fmt.Errorf("agenttask: project %q disappeared", projectID)
		}
		work, ok := project.Works[workID]
		if !ok {
			return fmt.Errorf("agenttask: work %q disappeared", workID)
		}
		if err := change(&work); err != nil {
			return err
		}
		work.UpdatedAt = m.clock.Now()
		project.Works[workID] = work
		project.UpdatedAt = m.clock.Now()
		state.Projects[projectID] = project
		return nil
	})
}

func (m *Manager) blockWork(
	ctx context.Context,
	projectID ProjectID,
	workID WorkUnitID,
	state WorkState,
	blocker Blocker,
) {
	_ = m.changeWork(ctx, projectID, workID, func(work *WorkRecord) error {
		stage := failureStageForState(work.State)
		blocker = m.recordFailure(work, stage, blocker)
		if CanTransition(work.State, state) {
			work.State = state
		} else {
			work.State = WorkStateBlocked
		}
		work.Blocker = &blocker
		return nil
	})
	m.emit(ctx, Event{
		Type: EventBlocked, ProjectID: projectID, WorkUnitID: workID,
		State: state, Detail: string(blocker.Code),
	})
}