feat(blocks): add ConcatenateListsBlock for list concatenation

[majiayu000]

Summary

Implements a new block that concatenates two or more lists into a single list.

• Two required inputs (list1, list2) for basic use
• Three optional advanced inputs (list3, list4, list5) for more complex scenarios
• Preserves element order during concatenation
• Outputs both the concatenated result and total element count

Test plan

• Block includes built-in test_input and test_output for automated testing
• Code passes format and lint checks

Fixes #11139

[coderabbitai]

Walkthrough

The PR adds a new ConcatenateListsBlock to the basic blocks module that merges up to five input lists into a single concatenated list, outputting both the combined result and its total length.

Changes

Cohort / File(s)	Summary
List Concatenation Block autogpt_platform/backend/backend/blocks/basic.py	Added ConcatenateListsBlock class with nested Input and Output classes. Accepts five lists (two required: list1, list2; three optional: list3–list5) and uses itertools.chain to concatenate them into a single list. Outputs the concatenated list and its total length. Includes metadata, input/output schemas, and test fixtures.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 A furry block of magic brew,
Five lists now merged into one new,
With chain and care, we hop along,
Concatenate our data song! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% 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
Title check	✅ Passed	The title clearly and concisely describes the main change: adding a new ConcatenateListsBlock for concatenating lists, which is the primary purpose of this pull request.
Description check	✅ Passed	The description is directly related to the changeset, providing details about the block's functionality, input/output specifications, and testing approach.
Linked Issues check	✅ Passed	The pull request fully implements the requirement from issue #11139 by providing a block that concatenates two or more lists into one with proper input/output handling.
Out of Scope Changes check	✅ Passed	All changes are directly related to implementing the ConcatenateListsBlock as specified in the linked issue; no out-of-scope modifications detected.

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✨ Finishing touches

• 📝 Generate docstrings

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📜 Recent review details

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📥 Commits

Reviewing files that changed from the base of the PR and between 290d0d9 and d36cbe9.

📒 Files selected for processing (1)

• autogpt_platform/backend/backend/blocks/basic.py

🧰 Additional context used

📓 Path-based instructions (4)

autogpt_platform/backend/**/*.py

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

autogpt_platform/backend/**/*.py: Always run backend setup commands in order: poetry install, poetry run prisma migrate dev, poetry run prisma generate before backend development
Always run poetry run format (Black + isort) before poetry run lint (ruff) for backend code
Use Python 3.10-3.13 with Python 3.11 required for development (managed by Poetry via pyproject.toml)

Run linting and formatting: use poetry run format (Black + isort) to auto-fix, and poetry run lint (ruff) to check remaining errors

Files:

• autogpt_platform/backend/backend/blocks/basic.py

autogpt_platform/backend/backend/blocks/**/*.py

📄 CodeRabbit inference engine (.github/copilot-instructions.md)

Agent blocks in backend/blocks/ must include: block definition with input/output schemas, execution logic with proper error handling, and tests validating functionality. Blocks inherit from Block base class with input/output schemas, implement run method, use uuid.uuid4() for block UUID, and be registered in block registry

Files:

• autogpt_platform/backend/backend/blocks/basic.py

autogpt_platform/{backend,autogpt_libs}/**/*.py

📄 CodeRabbit inference engine (AGENTS.md)

Format Python code with poetry run format

Files:

• autogpt_platform/backend/backend/blocks/basic.py

autogpt_platform/backend/**

📄 CodeRabbit inference engine (autogpt_platform/CLAUDE.md)

autogpt_platform/backend/**: Install dependencies for backend using poetry install
Run database migrations using poetry run prisma migrate dev

Files:

• autogpt_platform/backend/backend/blocks/basic.py

🧠 Learnings (4)

📚 Learning: 2025-11-25T08:48:33.246Z

Learnt from: CR
Repo: Significant-Gravitas/AutoGPT PR: 0
File: .github/copilot-instructions.md:0-0
Timestamp: 2025-11-25T08:48:33.246Z
Learning: Applies to autogpt_platform/backend/backend/blocks/**/*.py : Agent blocks in backend/blocks/ must include: block definition with input/output schemas, execution logic with proper error handling, and tests validating functionality. Blocks inherit from Block base class with input/output schemas, implement run method, use uuid.uuid4() for block UUID, and be registered in block registry

Applied to files:

• autogpt_platform/backend/backend/blocks/basic.py

📚 Learning: 2025-11-25T08:49:03.583Z

Learnt from: CR
Repo: Significant-Gravitas/AutoGPT PR: 0
File: autogpt_platform/CLAUDE.md:0-0
Timestamp: 2025-11-25T08:49:03.583Z
Learning: Applies to autogpt_platform/backend/blocks/**/*.py : Implement async `run` method in block classes for backend

Applied to files:

• autogpt_platform/backend/backend/blocks/basic.py

📚 Learning: 2025-11-25T08:49:03.583Z

Learnt from: CR
Repo: Significant-Gravitas/AutoGPT PR: 0
File: autogpt_platform/CLAUDE.md:0-0
Timestamp: 2025-11-25T08:49:03.583Z
Learning: Applies to autogpt_platform/backend/blocks/**/*.py : Inherit from `Block` base class and define input/output schemas using `BlockSchema` for backend blocks

Applied to files:

• autogpt_platform/backend/backend/blocks/basic.py

📚 Learning: 2025-11-25T08:49:03.583Z

Learnt from: CR
Repo: Significant-Gravitas/AutoGPT PR: 0
File: autogpt_platform/CLAUDE.md:0-0
Timestamp: 2025-11-25T08:49:03.583Z
Learning: Applies to autogpt_platform/backend/blocks/**/*.py : Generate unique block ID using `uuid.uuid4()` for each new block

Applied to files:

• autogpt_platform/backend/backend/blocks/basic.py

🧬 Code graph analysis (1)

autogpt_platform/backend/backend/blocks/basic.py (2)

autogpt_platform/backend/backend/data/block.py (3)

• BlockSchemaInput (339-345)
• BlockSchemaOutput (348-356)
• BlockCategory (77-101)

autogpt_platform/backend/backend/data/model.py (1)

• SchemaField (257-309)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (6)

• GitHub Check: types
• GitHub Check: Seer Code Review
• GitHub Check: test (3.11)
• GitHub Check: test (3.13)
• GitHub Check: test (3.12)
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🔇 Additional comments (2)

autogpt_platform/backend/backend/blocks/basic.py (2)

1-2: LGTM!

The itertools import is appropriate for the efficient list concatenation implementation.

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274-286: LGTM!

The implementation efficiently uses itertools.chain to concatenate lists without creating intermediate copies. The method correctly yields both outputs.

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[qodo-code-review]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 PR contains tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Mutable Defaults The optional inputs use default=[], which can behave as a shared mutable default depending on how the schema layer instantiates/handles defaults. Prefer using a default_factory=list (or equivalent pattern supported by SchemaField) to avoid unintended cross-instance mutation. list3: list[Any] = SchemaField( description="Optional third list to concatenate", default=[], advanced=True, ) list4: list[Any] = SchemaField( description="Optional fourth list to concatenate", default=[], advanced=True, ) list5: list[Any] = SchemaField( description="Optional fifth list to concatenate", default=[], advanced=True, ) Input Optionality The fields list3-list5 are described as optional but are typed as required list[Any] with an empty-list default. If callers explicitly pass null/None (e.g., via JSON), list(None) will raise. Consider typing as list[Any] | None and normalizing to [] (or ensuring the schema forbids None) to make “optional” behavior robust. list3: list[Any] = SchemaField( description="Optional third list to concatenate", default=[], advanced=True, ) list4: list[Any] = SchemaField( description="Optional fourth list to concatenate", default=[], advanced=True, ) list5: list[Any] = SchemaField( description="Optional fifth list to concatenate", default=[], advanced=True, ) class Output(BlockSchemaOutput): concatenated_list: list[Any] = SchemaField( description="The concatenated list containing all input list elements" ) total_length: int = SchemaField( description="The total number of elements in the concatenated list" ) def __init__(self): super().__init__( id="a1b2c3d4-5e6f-7a8b-9c0d-1e2f3a4b5c6d", description="Concatenates two or more lists into a single list, preserving element order", categories={BlockCategory.BASIC}, input_schema=ConcatenateListsBlock.Input, output_schema=ConcatenateListsBlock.Output, test_input={"list1": [1, 2, 3], "list2": [4, 5, 6]}, test_output=[ ("concatenated_list", [1, 2, 3, 4, 5, 6]), ("total_length", 6), ], ) async def run(self, input_data: Input, **kwargs) -> BlockOutput: result = ( list(input_data.list1) + list(input_data.list2) + list(input_data.list3) + list(input_data.list4) + list(input_data.list5) ) Efficiency/Clarity Concatenation currently creates multiple intermediate lists and repeatedly copies. Consider using itertools.chain (or a loop with extend) to reduce intermediate allocations and simplify future expansion to more than five lists. async def run(self, input_data: Input, **kwargs) -> BlockOutput: result = ( list(input_data.list1) + list(input_data.list2) + list(input_data.list3) + list(input_data.list4) + list(input_data.list5) )

[ntindle]

@coderabbitai review

[ntindle]

is there a better way to hanlde this? it seems --- tedious to upkeep

[ntindle]

comments + tests fail

[ntindle]

regenerate this using python uuid fucntions

[ntindle]

idk man why do we need five vs two vs 3 here?

[CLAassistant]

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1 out of 2 committers have signed the CLA.

✅ majiayu000
❌ Antigravity AI

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[ntindle]

we have decide to merge a competing pr. closing: #11567