kandev/docs/plans/workflow-empty-prompt-dedup/task-01-deduplicate-empty-workflow-prompts.md

id, title, status, wave, depends_on, plan, requirements, acceptance_criteria, system_design

id	title	status	wave	depends_on	plan	requirements	acceptance_criteria	system_design
01-deduplicate-empty-workflow-prompts	Deduplicate empty workflow prompts	done	1		plan.md	REQ-TASKS-WORKFLOW-STEP-AGENT-START-OWNERSHIP-003	AC-TASKS-WORKFLOW-STEP-AGENT-START-OWNERSHIP-003.1 AC-TASKS-WORKFLOW-STEP-AGENT-START-OWNERSHIP-003.2 AC-TASKS-WORKFLOW-STEP-AGENT-START-OWNERSHIP-003.3 AC-TASKS-WORKFLOW-STEP-AGENT-START-OWNERSHIP-003.4 AC-TASKS-WORKFLOW-STEP-AGENT-START-OWNERSHIP-003.5 AC-TASKS-WORKFLOW-STEP-AGENT-START-OWNERSHIP-003.6 AC-TASKS-WORKFLOW-STEP-AGENT-START-OWNERSHIP-003.7	../../specs/tasks/system-design/workflow-step-agent-start-ownership.md

Task 01: Deduplicate Empty Workflow Prompts

Summary

Add a durable prompt-history counter and atomic first-prompt claim for workflow prompt composition. Only an empty step prompt can use the task description as the one-time fallback.

In scope

• Add a bounded prompt-history query to the task repository.
• Apply the query in both workflow-step prompt paths.
• Keep ACP and passthrough behavior aligned.
• Preserve non-empty step prompts and ACP handoffs.
• Add deterministic repository and orchestrator tests.

Out of scope

• Plan-mode step placement.
• Start-step resolution.
• New persisted fields.
• Frontend tool-name text.

Acceptance

• An empty automatic-start step does not repeat a task description for a prompted session.
• An unprompted session still receives the task description once.
• A non-empty step prompt still dispatches, and an empty result creates no turn or message.
• Attachment-only handoffs are persisted and dispatched with their attachment metadata.
• Concurrent direct and automatic first-prompt admissions allow at most one initial fallback.

Verification

(cd apps/backend && go test -race -tags fts5 ./internal/task/repository/sqlite ./internal/orchestrator -run '^(TestHasUserPromptHistory|TestClaimInitialPromptFallbackSerializesPromptAdmission|TestDeleteTaskSessionRemovesPromptHistoryClaim|TestWorkflowAutoStartEmptyPrompt|TestWorkflowAutoStartNonEmptyPrompt|TestStartSessionForWorkflowStepEmptyPrompt|TestWorkflowAutoStartPlanModeOnlyPrompt|TestWorkflowAutoStartPlanModeOnlyPromptForCreatedSession|TestStartSessionForWorkflowStepPlanModeOnlyPrompt|TestWorkflowAutoStartAttachmentOnlyHandoffIsRecorded|TestWorkflowAutoStartPassthroughDrainsSuppressedHandoff)' -count=1)
make -C apps/backend test
make -C apps/backend lint
(cd apps/backend && golangci-lint run ./... --new-from-rev="$(git merge-base HEAD origin/main)" --timeout=5m)

Files likely touched

• apps/backend/internal/task/repository/interface.go
• apps/backend/internal/task/repository/sqlite/message_prompt_index.go
• apps/backend/internal/task/repository/sqlite/prompt_history_test.go
• apps/backend/internal/orchestrator/service.go
• apps/backend/internal/orchestrator/task_operations.go
• apps/backend/internal/orchestrator/event_handlers_workflow.go
• apps/backend/internal/orchestrator/event_handlers_initial_prompt_dedup_test.go
• apps/backend/internal/task/handlers/process_handlers_test.go

Dependencies

None.

Risks

• Repository interface changes can require test-double updates.
• The no-content branch can bypass a queued handoff if it runs too early.
• Prompt-history errors can leave the session waiting until a user retries.

Parallelism

sequential

Inputs

• REQ-TASKS-WORKFLOW-STEP-AGENT-START-OWNERSHIP-003
• Prompt fallback ownership and workflow-entry prompt flow in the system design.
• Existing prompt-counter allocation in message_prompt_index.go.
• Existing auto-start recovery tests in event_handlers_duplicate_autostart_test.go.

Results

• Added the durable HasUserPromptHistory query plus the atomic ClaimInitialPromptFallback admission boundary and applied one entry-prompt decision to automatic and explicit workflow-step launches.
• Added coverage for prompted and unprompted empty steps, non-empty step prompts, passthrough suppression, prompt-history errors, plan-mode-only instructions, attachment-only handoffs, prompt-admission races, session-ID reuse cleanup, and the no-turn/no-message empty result.
• The focused race suite passed with 18 tests, including both prompt-admission orderings, concurrent fallback claims, plan-only prompts, attachment-only handoffs, passthrough draining, and session-ID reuse cleanup.
• env KANDEV_INTERNAL_CONFIG_FILE= KANDEV_INTERNAL_CONFIG_HOME_FILE= make -C apps/backend test passed for every backend package. The unmodified make -C apps/backend test form was also attempted, but this task session's injected launcher config caused unrelated home-config discovery failures.
• make -C apps/backend lint passed with 0 issues.
• golangci-lint run ./... --new-from-rev=0064b9fb5a903feeb6cffc2ce6b7db1c16218e6e --timeout=5m passed with no issues.