feat: carry push-back context into AI steps

[yottahmd]

Summary

• carry push-back iteration and feedback through AI step re-execution without DAG glue
• preserve previous stdout log paths for rewound harness steps and expose them via env/prompt context
• restore prior chat/agent conversation context for push-back re-execution, including rewind-to upstream AI steps

Validation

• go test ./internal/service/frontend/api/v1 -run TestApplyPushBackRewindToResetsNamedStepAndDependents
• go test ./internal/runtime -run 'TestSetupPushBackConversation|TestPushBackInputsExposeJSONHistoryEnv'
• go test ./internal/runtime/builtin/harness ./internal/runtime/builtin/chat ./internal/runtime/builtin/agentstep
• go test ./internal/runtime/transform ./internal/core/exec ./internal/proto/convert
• go test ./internal/service/coordinator ./internal/runtime/executor
• go test ./internal/intg -run 'TestApprovalPushBack|Test.*Approval'
• git diff --check

Summary by CodeRabbit

Release Notes

• New Features
  • Push-back iterations now preserve and expose previous step output logs for reviewer reference during step rewinding and resumption.
  • Enhanced reviewer feedback handling for chat and harness-based steps with improved iteration context tracking during push-back operations.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 4af9cabb-5ae1-410e-a423-9c0a2bd06323

📥 Commits

Reviewing files that changed from the base of the PR and between 129d2f0 and c19ea1d.

📒 Files selected for processing (15)

• internal/core/exec/env.go
• internal/core/exec/node.go
• internal/runtime/builtin/chat/executor.go
• internal/runtime/builtin/chat/executor_test.go
• internal/runtime/builtin/harness/harness.go
• internal/runtime/builtin/harness/harness_test.go
• internal/runtime/data.go
• internal/runtime/executor/executor.go
• internal/runtime/export_test.go
• internal/runtime/node.go
• internal/runtime/runner.go
• internal/runtime/runner_test.go
• internal/runtime/transform/node.go
• internal/service/frontend/api/v1/dagruns.go
• internal/service/frontend/api/v1/dagruns_internal_test.go

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📝 Walkthrough

Walkthrough

This PR adds support for capturing and propagating the previous stdout of rewound DAG nodes during push-back iterations. New environment variables, node fields, and executor interfaces enable chat and harness executors to access previous stdout when re-executing steps with reviewer feedback.

Changes

Push-Back Previous Stdout Propagation

Layer / File(s)	Summary
Data Shape internal/core/exec/env.go, internal/core/exec/node.go, internal/runtime/data.go	New constants EnvKeyDAGPushBackIteration and EnvKeyDAGPushBackPreviousStdoutFile added. Node struct gains PushBackPreviousStdout field to store stdout path. NodeState gains matching PushBackPreviousStdout field for runtime state.
Interfaces & Contracts internal/runtime/executor/executor.go	New public interface PushBackPreviousStdoutAware added with SetPushBackPreviousStdout(path string) method to allow executors to receive previous stdout context.
Chat Executor Push-Back internal/runtime/builtin/chat/executor.go	Executor gains pushBackInputs and pushBackIteration fields. Implements PushBackAware, SubRunProvider, and ToolDefinitionProvider. New SetPushBackContext API exposes push-back inputs and iteration. executionMessages path evaluates messages and optionally injects feedback as a system+user message. New systemMessages and formatPushBackFeedback helpers format reviewer feedback with approved keys.
Harness Executor Push-Back internal/runtime/builtin/harness/harness.go	Executor struct expanded with pushBackInputs, pushBackIteration, pushBackPreviousStdout. Implements PushBackAware and PushBackPreviousStdoutAware. New SetPushBackContext and SetPushBackPreviousStdout methods configure push-back state. effectivePrompt() augments the prompt with push-back context, sorted feedback keys, and optional previous stdout log path. Command invocation uses effective prompt instead of raw prompt.
Runtime Wiring internal/runtime/runner.go, internal/runtime/node.go	Runner injects DAG_PUSHBACK_ITERATION and DAG_PUSHBACK_PREVIOUS_STDOUT_FILE environment variables for AI-enabled steps. Node.Execute propagates previous stdout to executors implementing PushBackPreviousStdoutAware when approval iteration is active.
State Propagation internal/runtime/transform/node.go	Transform layer includes PushBackPreviousStdout in NodeState and exec.Node construction, enabling round-trip persistence and retrieval.
API Layer internal/service/frontend/api/v1/dagruns.go	setPushBackContext signature updated to accept previousStdout parameter. Push-back rewind logic captures node's previous stdout before resetting and stores it on the node state via new field.
Tests internal/runtime/builtin/chat/executor_test.go, internal/runtime/builtin/harness/harness_test.go, internal/runtime/runner_test.go, internal/runtime/export_test.go, internal/service/frontend/api/v1/dagruns_internal_test.go	New chat executor test validates push-back message flow with feedback. New harness test validates prompt augmentation with log path reference. Runner tests added for chat/agent step push-back and extended environment variable handling. Export test helper SetPushBackPreviousStdout added. DAG runs test updated with previous stdout assertions across node indices.

Sequence Diagram

sequenceDiagram
    participant DagAPI as DAG API<br/>(dagruns.go)
    participant Runner as Runner<br/>(runner.go)
    participant Node as Node<br/>(node.go)
    participant Executor as Executor<br/>(chat/harness)
    participant State as State<br/>(data.go)

    DagAPI->>DagAPI: Capture node.Stdout<br/>before reset
    DagAPI->>DagAPI: Call setPushBackContext<br/>with previousStdout
    DagAPI->>State: Store PushBackPreviousStdout<br/>in NodeState
    
    Runner->>Runner: setupNodeExecutionEnv
    Runner->>Runner: Inject env vars:<br/>DAG_PUSHBACK_ITERATION<br/>DAG_PUSHBACK_PREVIOUS_STDOUT_FILE
    
    Node->>Executor: Execute command
    Executor->>Executor: Check if implements<br/>PushBackPreviousStdoutAware
    
    Node->>Executor: SetPushBackPreviousStdout(path)<br/>if ApprovalIteration > 0
    
    Executor->>Executor: Use previous stdout<br/>in message/prompt<br/>construction
    Executor->>Executor: Format feedback<br/>with context
    Executor->>Executor: Augment prompt<br/>with log reference

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• dagucloud/dagu#2080: Modifies the same runner environment setup for push-back (internal/runtime/runner.go), injecting push-back-related env vars before precondition evaluation.
• dagucloud/dagu#2038: Extends push-back machinery at the code level across the same files (internal/core/exec/env.go, internal/core/exec/node.go, runtime runner/transform paths), managing push-back-related env vars and node state.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 16.67% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'feat: carry push-back context into AI steps' accurately summarizes the main change: enabling push-back iteration, feedback, and previous stdout context to be propagated through AI step re-execution.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/pushback-context

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