wap-ingestion

# Write-Audit-Publish (WAP) Pattern

Implement WAP by writing a Python script using the `bauplan` SDK. Do NOT use CLI commands.

**The three steps**: Write (ingest to temp branch) → Audit (quality checks) → Publish (merge to main)

**Branch safety**: All operations happen on a temporary branch, NEVER on `main`. By default, branches are kept open for inspection after success or failure.

**Atomic multi-table operations**: `merge_branch` is atomic. You can create or modify multiple tables on a branch, and when you merge, either all changes apply to main or none do. This enables safe multi-table ingestion workflows.

## Required User Input

Before writing the WAP script, you MUST ask the user for the following parameters:

1. **S3 path** (required): The S3 URI pattern for the source data (e.g., `s3://bucket/path/*.parquet`)
2. **Table name** (required): The name for the target table
3. **On success behavior** (optional):
   - `inspect` (default): Keep the branch open for user inspection before merging
   - `merge`: Automatically merge to main and delete the branch
4. **On failure behavior** (optional):
   - `keep` (default): Leave the branch open for inspection/debugging
   - `delete`: Delete the failed branch

## WAP Script Template

See [wap_template.py](wap_template.py) for the complete template. Minimal usage:

```python
from wap_template import wap_ingest

branch, success = wap_ingest(
    table_name="orders",
    s3_path="s3://my-bucket/data/*.parquet",
    namespace="bauplan",
    on_success="inspect",  # or "merge"
    on_failure="keep"      # or "delete"
)
```

## Key SDK Methods

| Method | Description |
|--------|-------------|
| `bauplan.Client()` | Initialize the bauplan client |
| `client.info()` | Get client info; access username via `.user.username` |
| `client.create_branch(name, from_ref="main")` | Create a new branch from specified ref |
| `client.has_branch(name)` | Check if branch exists |
| `client.delete_branch(name)` | Delete a branch |
| `client.create_table(table, search_uri, ...)` | Create table with schema inferred from S3 |
| `client.import_data(table, search_uri, ...)` | Import data from S3 into table |
| `client.query(query, ref)` | Run SQL query, returns PyArrow Table |
| `client.merge_branch(source_ref, into_branch)` | Merge branch into target |
| `client.has_table(table, ref, namespace)` | Check if table exists on branch |

> **SDK Reference**: For detailed method signatures, check https://docs.bauplanlabs.com/reference/bauplan

## Workflow Checklist

Copy and track progress:

```
WAP Progress:
- [ ] Ask user for: S3 path, table name, on_success, on_failure
- [ ] Write script using wap_template.py
- [ ] Run script: python wap_script.py
- [ ] Verify output shows row count > 0
- [ ] If on_success="inspect": confirm branch ready for review
- [ ] If on_success="merge": confirm merge to main succeeded
```

## Example Output

**Successful run (on_success="inspect")**:
```
$ python wap_script.py
Imported 15234 rows
WAP completed successfully. Branch 'alice.wap_orders_1704067200' ready for inspection.
To merge manually: client.merge_branch(source_ref='alice.wap_orders_1704067200', into_branch='main')
```

**Successful run (on_success="merge")**:
```
$ python wap_script.py
Imported 15234 rows
Successfully published orders to main
Cleaned up branch: alice.wap_orders_1704067200
```

**Failed run (on_failure="keep")**:
```
$ python wap_script.py
WAP failed: No data was imported
Branch 'alice.wap_orders_1704067200' preserved for inspection/debugging.
```

## WAP on Existing Tables

To append data to an existing table, skip `create_table` and only call `import_data`:

```python
# Table already exists on main - just import new data
client.import_data(
    table=table_name,
    search_uri=s3_path,
    namespace=namespace,
    branch=branch_name
)
```

This appends rows to the existing table schema. The audit and publish phases remain the same: the new rows are automatically sandboxed on the branch until merged.

## CLI Merge After Inspection

When `on_success="inspect"` (default), the branch is left open for user review. If the user asks to merge after inspecting the data, use the CLI:

```bash
# 1. Checkout to main first (required before merging)
bauplan checkout main

# 2. Merge the WAP branch into main
bauplan branch merge <username>.wap_<table_name>_<timestamp>

# 3. Optionally delete the branch after successful merge
bauplan branch rm <username>.wap_<table_name>_<timestamp>
```

> **Note**: You must be on `main` to run `bauplan branch merge`. The branch name is printed by the WAP script upon completion.