neo4j-aura-graph-analytics-skill

## When to Use
- Running GDS algorithms in Aura Graph Analytics GDS Sessions
- Creating `GdsSessions` or using `AuraGraphDataScience`
- Remote projecting connected Neo4j data with `gds.graph.project.remote(...)`
- Using AuraDB Cypher API projection with `{ memory: ... }` or `{ sessionId: ... }`
- Processing graph data from non-Neo4j sources (Pandas, Spark, CSV)
- On-demand / pipeline workloads — ephemeral sessions, pay per session-minute
- Full isolation from the live database during analytics

## When NOT to Use
- **Aura Pro with embedded GDS plugin** → `neo4j-gds-skill`
- **Self-managed Neo4j with embedded GDS plugin** → `neo4j-gds-skill`
- **Writing Cypher queries** → `neo4j-cypher-skill`
- **Snowflake Graph Analytics** → `neo4j-snowflake-graph-analytics-skill`

---

## Deployment Decision Table

| Deployment | Use |
|---|---|
| Aura Free | ❌ AGA not available |
| Aura Pro | `neo4j-gds-skill` (embedded plugin) |
| AuraDB + Python client sessions | **this skill** |
| AuraDB + Cypher API | **this skill** for AGA-specific projection/session notes; `neo4j-cypher-skill` for query authoring |
| Self-managed Neo4j + AGA session | **this skill** |
| Self-managed Neo4j + embedded plugin | `neo4j-gds-skill` |
| Non-Neo4j data (Pandas, Spark) | **this skill** (standalone mode) |

---

## Defaults

- `graphdatascience >= 1.15` required; `>= 1.18` for Spark
- Prefer v2 endpoints: `gds.v2.graph.project(...)`, `gds.v2.page_rank.*`, `gds.v2.graph.node_properties.*`
- Use snake_case parameters end-to-end; never mix v2 with camelCase params
- Use v1 if v2 endpoint missing/incompatible; label fallback
- Call `gds.v2.verify_session_connectivity()` after session creation
- Connected sessions: call `gds.v2.verify_db_connectivity()` when source DB access required
- Estimate memory before large sessions
- Set TTL; default 1h idle, max 7d
- Close session when done: `gds.delete()` or `sessions.delete(name)` stops billing
- Use `AuraAPICredentials.from_env()` — never hardcode credentials

---

## Installation

```bash
pip install "graphdatascience>=1.15"
```

---

## Key Patterns

### Step 1 — Authenticate

```python
import os
from graphdatascience.session import AuraAPICredentials, GdsSessions

sessions = GdsSessions(api_credentials=AuraAPICredentials.from_env())
# Reads: AURA_CLIENT_ID, AURA_CLIENT_SECRET, AURA_PROJECT_ID (optional)
# Create API credentials in Aura Console → Account → API credentials
```

If member of multiple projects: set `AURA_PROJECT_ID` or pass `project_id=`.

### Step 2 — Estimate Memory

```python
from graphdatascience.session import AlgorithmCategory, SessionMemory

memory = sessions.estimate(
    node_count=1_000_000,
    relationship_count=5_000_000,
    algorithm_categories=[
        AlgorithmCategory.CENTRALITY,
        AlgorithmCategory.NODE_EMBEDDING,
        AlgorithmCategory.COMMUNITY_DETECTION,
    ],
)
# Returns SessionMemory tier, e.g. SessionMemory.m_8GB
# Fixed tiers: m_2GB … m_256GB — see references/limitations.md
```

### Step 3 — Create Session

**Mode A — AuraDB connected:**
```python
from graphdatascience.session import DbmsConnectionInfo, SessionMemory, CloudLocation
from datetime import timedelta

db_connection = DbmsConnectionInfo(
    username=os.environ["NEO4J_USERNAME"],
    password=os.environ["NEO4J_PASSWORD"],
    aura_instance_id=os.environ["AURA_INSTANCEID"],  # from Aura Console URL
)

gds = sessions.get_or_create(
    session_name="my-analysis",
    memory=memory,
    db_connection=db_connection,
    ttl=timedelta(hours=2),
)
gds.v2.verify_session_connectivity()
gds.v2.verify_db_connectivity()
```

**Mode B — Self-managed Neo4j:**
```python
db_connection = DbmsConnectionInfo(
    uri=os.environ["NEO4J_URI"],          # e.g. "bolt://my-server:7687"
    username=os.environ["NEO4J_USERNAME"],
    password=os.environ["NEO4J_PASSWORD"],
)
gds = sessions.get_or_create(
    session_name="my-analysis-sm",
    memory=SessionMemory.m_8GB,
    db_connection=db_connection,
    ttl=timedelta(hours=2),
    cloud_location=CloudLocation("gcp", "europe-west1"),
)
gds.v2.verify_session_connectivity()
gds.v2.verify_db_connectivity()
```

**Mode C — Standalone (no Neo4j DB):**
```python
gds = sessions.get_or_create(
    session_name="my-standalone",
    memory=SessionMemory.m_4GB,
    ttl=timedelta(hours=1),
    cloud_location=CloudLocation("gcp", "europe-west1"),
)
gds.v2.verify_session_connectivity()
```

`get_or_create()` is idempotent; reconnects to existing session by name.

### Step 4 — Project Graph

**From connected Neo4j (remote projection):**
```python
query = """
    CALL () {
        MATCH (p:Person)
        OPTIONAL MATCH (p)-[r:KNOWS]->(p2:Person)
        RETURN p AS source, r AS rel, p2 AS target,
               p {.age, .score} AS sourceNodeProperties,
               p2 {.age, .score} AS targetNodeProperties
    }
    RETURN gds.graph.project.remote(source, target, {
        sourceNodeLabels:     labels(source),
        targetNodeLabels:     labels(target),
        sourceNodeProperties: sourceNodeProperties,
        targetNodeProperties: targetNodeProperties,
        relationshipType:     type(rel)
    })
"""

G, result = gds.v2.graph.project(
    graph_name="my-graph",
    query=query,
    undirected_relationship_types=["KNOWS"],
)
print(f"Projected {G.node_count()} nodes, {G.relationship_count()} relationships")
```

`CALL () { ... }` required for multi-pattern MATCH. Use `UNION` inside `CALL` for multiple labels/rel types.
Remote query uses `gds.graph.project.remote(...)`; pass graph name to `gds.v2.graph.project(...)`, not query.
V1 fallback: `gds.graph.project(graph_name="my-graph", query=query, undirected_relationship_types=["KNOWS"])`.

**AuraDB Cypher API projection:**
```cypher
CYPHER runtime=parallel
MATCH (source)
OPTIONAL MATCH (source)-->(target)
RETURN gds.graph.project(
  'my-graph',
  source,
  target,
  {},
  { memory: '2GB' }
)
```

Existing explicit session:
```cypher
CYPHER runtime=parallel
MATCH (source)
OPTIONAL MATCH (source)-->(targe