Update marimo notebook docs with lessons from workflow debugging

- Add rules: all imports in setup cell, cell output at top level,
  async cells need async def, return classes from model cells,
  use python-dotenv for .env loading
- Add marimo check validation step to AGENTS.md and notebook-patterns.md
- Add "always create new workflow" rule to AGENTS.md
- Add new doc sections: Cell Output Must Be at the Top Level,
  Async Cells, Cells That Define Classes, Fixing _unparsable_cell,
  Checking Notebooks Before Running
- Update all code examples to follow new import/output rules
- Update workflows/lib/llm.py for mirascope v2 API
This commit is contained in:
2026-02-10 19:25:53 -06:00
parent 439e9db0a4
commit d04aa26f31
3 changed files with 182 additions and 30 deletions

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@@ -25,11 +25,11 @@ def cell_two(x):
**Key rules:**
- Cells declare dependencies via function parameters
- Cells return values as tuples: `return (var1, var2,)`
- The **last expression** in a cell is displayed as rich output in the marimo UI (dataframes render as tables, dicts as collapsible trees)
- The **last expression at the top level** of a cell is displayed as rich output in the marimo UI (dataframes render as tables, dicts as collapsible trees). Expressions inside `if`/`else`/`for` blocks do **not** count — see [Cell Output Must Be at the Top Level](#cell-output-must-be-at-the-top-level) below
- Use `mo.md("# heading")` for formatted markdown output (import `mo` once in setup — see below)
- No manual execution order; the DAG determines it
- **Variable names must be unique across cells.** Every variable assigned at the top level of a cell is tracked by marimo's DAG. If two cells both define `resp`, marimo raises `MultipleDefinitionError` and refuses to run. Prefix cell-local variables with `_` (e.g., `_resp`, `_rows`, `_data`) to make them **private** to that cell — marimo ignores `_`-prefixed names.
- **Import shared modules once** in a single setup cell and pass them as cell parameters. Do NOT `import marimo as mo` in multiple cells — that defines `mo` twice. Instead, import it once in `setup` and receive it via `def my_cell(mo):`.
- **All imports must go in the `setup` cell.** Every `import` statement creates a top-level variable (e.g., `import asyncio` defines `asyncio`). If two cells both `import asyncio`, marimo raises `MultipleDefinitionError`. Place **all** imports in a single setup cell and pass them as cell parameters. Do NOT `import marimo as mo` or `import asyncio` in multiple cells — import once in `setup`, then receive via `def my_cell(mo, asyncio):`.
### Cell Variable Scoping — Example
@@ -79,6 +79,112 @@ def fetch_details(client, DATAINDEX, results):
> **Note:** Variables inside nested `def` functions are naturally local and don't need `_` prefixes — e.g., `resp` inside a `def fetch_all(...)` helper is fine because it's scoped to the function, not the cell.
### Cell Output Must Be at the Top Level
Marimo only renders the **last expression at the top level** of a cell as rich output. An expression buried inside an `if`/`else`, `for`, `try`, or any other block is **not** displayed — it's silently discarded.
**BROKEN**`_df` inside the `if` branch is never rendered:
```python
@app.cell
def show_results(results, mo):
if results:
_df = pl.DataFrame(results)
mo.md(f"**Found {len(results)} results**")
_df # Inside an if block — marimo does NOT display this
else:
mo.md("**No results found**")
return
```
**FIXED** — assign inside the branches, display at the top level:
```python
@app.cell
def show_results(results, mo):
_output = None
if results:
_output = pl.DataFrame(results)
mo.md(f"**Found {len(results)} results**")
else:
mo.md("**No results found**")
_output # Top-level last expression — marimo renders this
return
```
**Rule of thumb:** initialize a `_output = None` variable before any conditional, assign the displayable value inside the branches, then put `_output` as the last top-level expression. When it's `None` (e.g., the `else` path), marimo shows nothing — which is fine since the `mo.md()` already provides feedback.
### Async Cells
When a cell uses `await` (e.g., for `llm_call` or `asyncio.gather`), you **must** declare it as `async def`:
```python
@app.cell
async def analyze(meetings, llm_call, ResponseModel, asyncio):
async def _score(meeting):
return await llm_call(prompt=..., response_model=ResponseModel)
results = await asyncio.gather(*[_score(_m) for _m in meetings])
return (results,)
```
Note that `asyncio` is imported in the `setup` cell and received here as a parameter — never `import asyncio` inside individual cells.
If you write `await` in a non-async cell, marimo cannot parse the cell and saves it as an `_unparsable_cell` string literal — the cell won't run, and you'll see `SyntaxError: 'return' outside function` or similar errors. See [Fixing `_unparsable_cell`](#fixing-_unparsable_cell) below.
### Cells That Define Classes Must Return Them
If a cell defines Pydantic models (or any class) that other cells need, it **must** return them:
```python
@app.cell
def models():
from pydantic import BaseModel
class MeetingSentiment(BaseModel):
overall_sentiment: str
sentiment_score: int
class FrustrationExtraction(BaseModel):
has_frustrations: bool
frustrations: list[dict]
return MeetingSentiment, FrustrationExtraction # Other cells receive these as parameters
```
A bare `return` (or no return) means those classes are invisible to the rest of the notebook.
### Fixing `_unparsable_cell`
When marimo can't parse a cell into a proper `@app.cell` function, it saves the raw code as `app._unparsable_cell("...", name="cell_name")`. These cells **won't run** and show errors like `SyntaxError: 'return' outside function`.
**Common causes:**
1. Using `await` without making the cell `async def`
2. Using `return` in code that marimo failed to wrap into a function (usually a side effect of cause 1)
**How to fix:** Convert the `_unparsable_cell` string back into a proper `@app.cell` decorated function:
```python
# BROKEN — saved as _unparsable_cell because of top-level await
app._unparsable_cell("""
results = await asyncio.gather(...)
return results
""", name="my_cell")
# FIXED — proper async cell function (asyncio imported in setup, received as parameter)
@app.cell
async def my_cell(some_dependency, asyncio):
results = await asyncio.gather(...)
return (results,)
```
**Key differences to note when converting:**
- Wrap the code in an `async def` function (if it uses `await`)
- Add cell dependencies as function parameters (including imports like `asyncio`)
- Return values as tuples: `return (var,)` not `return var`
- Prefix cell-local variables with `_`
- Never add `import` statements inside the cell — all imports belong in `setup`
### Inline Dependencies with PEP 723
Use PEP 723 `/// script` metadata so `uv run` auto-installs dependencies:
@@ -90,10 +196,25 @@ Use PEP 723 `/// script` metadata so `uv run` auto-installs dependencies:
# "marimo",
# "httpx",
# "polars",
# "mirascope[openai]",
# "pydantic",
# "python-dotenv",
# ]
# ///
```
### Checking Notebooks Before Running
Always run `marimo check` before opening or running a notebook. It catches common issues — duplicate variable definitions, `_unparsable_cell` blocks, branch expressions that won't display, and more — without needing to start the full editor:
```bash
uvx marimo check notebook.py # Check a single notebook
uvx marimo check workflows/ # Check all notebooks in a directory
uvx marimo check --fix notebook.py # Auto-fix fixable issues
```
**Run this after every edit.** A clean `marimo check` (no output, exit code 0) means the notebook is structurally valid. Any errors must be fixed before running.
### Running Notebooks
```bash
@@ -142,6 +263,9 @@ Every notebook against InternalAI follows this structure:
# "marimo",
# "httpx",
# "polars",
# "mirascope[openai]",
# "pydantic",
# "python-dotenv",
# ]
# ///
@@ -166,11 +290,15 @@ def config():
@app.cell
def setup():
from dotenv import load_dotenv
load_dotenv() # Load .env from the project root
import asyncio # All imports go here — never import inside other cells
import httpx
import marimo as mo
import polars as pl
client = httpx.Client(timeout=30)
return (client, mo, pl,)
return (asyncio, client, mo, pl,)
# --- your IN / ETL / OUT cells here ---
@@ -178,6 +306,8 @@ if __name__ == "__main__":
app.run()
```
> **`load_dotenv()`** reads the `.env` file from the project root (walks up from the notebook's directory). This makes `LLM_API_KEY` and other env vars available to `os.getenv()` calls in `lib/llm.py` without requiring the shell to have them pre-set. Always include `python-dotenv` in PEP 723 dependencies and call `load_dotenv()` early in the setup cell.
**The `params` cell must always be the first cell** after `app = marimo.App()`. It contains all user-configurable constants (search terms, date ranges, target names, etc.) as plain Python values. This way the user can tweak the workflow by editing a single cell at the top — no need to hunt through the code for hardcoded values.
## Pagination Helper
@@ -429,7 +559,7 @@ def display_timeline(timeline_df):
When you need to classify, score, or extract structured information from each entity (e.g. "is this meeting about project X?", "rate the relevance of this email"), use the `llm_call` helper from `workflows/lib`. It sends each item to an LLM and parses the response into a typed Pydantic model.
**Prerequisites:** Copy `.env.example` to `.env` and fill in your `LLM_API_KEY`. Add `mirascope` and `pydantic` to the notebook's PEP 723 dependencies.
**Prerequisites:** Copy `.env.example` to `.env` and fill in your `LLM_API_KEY`. Add `mirascope`, `pydantic`, and `python-dotenv` to the notebook's PEP 723 dependencies.
```python
# /// script
@@ -438,23 +568,28 @@ When you need to classify, score, or extract structured information from each en
# "marimo",
# "httpx",
# "polars",
# "mirascope",
# "mirascope[openai]",
# "pydantic",
# "python-dotenv",
# ]
# ///
```
### Setup cell — import `llm_call`
### Setup cell — load `.env` and import `llm_call`
```python
@app.cell
def setup():
from dotenv import load_dotenv
load_dotenv() # Makes LLM_API_KEY available to lib/llm.py
import asyncio
import httpx
import marimo as mo
import polars as pl
from lib.llm import llm_call
client = httpx.Client(timeout=30)
return (client, llm_call, mo, pl,)
return (asyncio, client, llm_call, mo, pl,)
```
### Define a response model
@@ -480,9 +615,7 @@ Iterate over fetched entities and call `llm_call` for each one. Since `llm_call`
```python
@app.cell
async def llm_filter(meetings, llm_call, RelevanceScore, pl, mo):
import asyncio
async def llm_filter(meetings, llm_call, RelevanceScore, pl, mo, asyncio):
_topic = "Greyhaven"
async def _score(meeting):
@@ -515,20 +648,26 @@ When generating marimo notebooks, follow these rules strictly. Violations cause
### Do
- **Prefix cell-local variables with `_`** — `_resp`, `_rows`, `_m`, `_data`, `_chunk`. Marimo ignores `_`-prefixed names so they won't clash across cells.
- **Import shared modules once in `setup`** and pass them as cell parameters: `def my_cell(client, mo, pl):`.
- **Put all imports in the `setup` cell** and pass them as cell parameters: `def my_cell(client, mo, pl, asyncio):`. Never `import` inside other cells — even `import asyncio` in two async cells causes `MultipleDefinitionError`.
- **Give returned DataFrames unique names** — `email_df`, `meeting_df`, `timeline_df`. Never use a bare `df` that might collide with another cell.
- **Return only values other cells need** — everything else should be `_`-prefixed and stays private to the cell.
- **Use `from datetime import datetime` inside the cell** that needs it (stdlib imports are fine inline since they're `_`-safe inside functions, but avoid assigning them to non-`_` names if another cell does the same).
- **Import stdlib modules in `setup` too** — even `from datetime import datetime` creates a top-level name. If two cells both import `datetime`, marimo errors. Import it once in `setup` and receive it as a parameter, or use it inside a `_`-prefixed helper function where it's naturally scoped.
- **Every non-utility cell must show a preview** — see the "Cell Output Previews" section below.
- **Keep cell output expressions at the top level** — if a cell conditionally displays a DataFrame, initialize `_output = None` before the `if`/`else`, assign inside the branches, then put `_output` as the last top-level expression. Expressions inside `if`/`else`/`for` blocks are silently ignored by marimo.
- **Put all user parameters in a `params` cell as the first cell** — date ranges, search terms, target names, limits. Never hardcode these values deeper in the notebook.
- **Declare cells as `async def` when using `await`** — `@app.cell` followed by `async def cell_name(...)`. This includes cells using `asyncio.gather`, `await llm_call(...)`, or any async API.
- **Return classes/models from cells that define them** — if a cell defines `class MyModel(BaseModel)`, return it so other cells can use it as a parameter: `return (MyModel,)`.
- **Use `python-dotenv` to load `.env`** — add `python-dotenv` to PEP 723 dependencies and call `load_dotenv()` early in the setup cell (before importing `lib.llm`). This ensures `LLM_API_KEY` and other env vars are available without requiring them to be pre-set in the shell.
### Don't
- **Don't define the same variable name in two cells** — even `resp = ...` in cell A and `resp = ...` in cell B is a fatal error.
- **Don't `import marimo as mo` in multiple cells** — this defines `mo` twice. Import it once in `setup`, then receive it via `def my_cell(mo):`.
- **Don't `import` inside non-setup cells** — every `import X` defines a top-level variable `X`. If two cells both `import asyncio`, marimo raises `MultipleDefinitionError` and refuses to run. Put all imports in the `setup` cell and receive them as function parameters.
- **Don't use generic top-level names** like `df`, `rows`, `resp`, `data`, `result` — either prefix with `_` or give them a unique descriptive name.
- **Don't return temporary variables** — if `_rows` is only used to build a DataFrame, keep it `_`-prefixed and only return the DataFrame.
- **Don't use `import X` at the top level of multiple cells** for the same module — the module variable name would be duplicated. Import once in `setup` or use `_`-prefixed local imports (`_json = __import__("json")`).
- **Don't use `await` in a non-async cell** — this causes marimo to save the cell as `_unparsable_cell` (a string literal that won't execute). Always use `async def` for cells that call async functions.
- **Don't define classes in a cell without returning them** — a bare `return` or no return makes classes invisible to the DAG. Other cells can't receive them as parameters.
- **Don't put display expressions inside `if`/`else`/`for` blocks** — marimo only renders the last top-level expression. A DataFrame inside an `if` branch is silently discarded. Use the `_output = None` pattern instead (see [Cell Output Must Be at the Top Level](#cell-output-must-be-at-the-top-level)).
## Cell Output Previews