# Index Backend Repro (Isolated)

## Summary

With a fresh store root, `amduatd` on `--store-backend index` accepts the first
`/v2/graph/nodes` write, then fails on the second node write with `{"error":"store error"}`.
The same call sequence succeeds on `--store-backend fs`.

Observed daemon log on index:

```text
ERROR: edge append failed for space/app1/daemon/edges (err=2)
```

`err=2` maps to `AMDUAT_ASL_COLLECTION_ERR_IO`.

## Minimal Repro

### 1) Start index backend

```bash
STORE_BACKEND=index INDEX_BACKEND_PROBE=0 \
STORE_ROOT=/tmp/amduat-asl-index-iso \
SOCK=/tmp/amduatd-index-iso.sock SPACE=app1 \
./scripts/dev_start_daemon.sh
```

### 2) Execute direct API calls

```bash
curl --globoff --silent --show-error --unix-socket /tmp/amduatd-index-iso.sock \
  -H 'Content-Type: application/json' -H 'X-Amduat-Space: app1' \
  -X POST --data-binary '{"name":"doca1"}' \
  http://localhost/v2/graph/nodes

curl --globoff --silent --show-error --unix-socket /tmp/amduatd-index-iso.sock \
  -H 'Content-Type: application/json' -H 'X-Amduat-Space: app1' \
  -X POST --data-binary '{"name":"topica1"}' \
  http://localhost/v2/graph/nodes

curl --globoff --silent --show-error --unix-socket /tmp/amduatd-index-iso.sock \
  -H 'Content-Type: application/json' -H 'X-Amduat-Space: app1' \
  -X POST --data-binary '{"subject":"doca1","predicate":"ms.within_domain","object":"topica1","provenance":{"source_uri":"urn:t","extractor":"x","observed_at":1,"ingested_at":2,"trace_id":"t1"}}' \
  http://localhost/v2/graph/edges
```

Expected: both nodes + edge succeed.
Actual on index: second node returns `{"error":"store error"}`, edge returns `{"error":"object not found"}`.

### 3) Control check (fs backend)

Run the same payloads against fs:

```bash
STORE_BACKEND=fs STORE_ROOT=/tmp/amduat-asl-fs-iso \
SOCK=/tmp/amduatd-fs-iso.sock SPACE=app1 \
./scripts/dev_start_daemon.sh
```

All three calls succeed on `fs`.

## Likely Failure Path

From source:

- `vendor/amduat-api/src/amduatd_concepts.c`
  - edge append path calls `amduat_asl_collection_append(...)`
- `vendor/amduat-api/vendor/amduat/src/core/asl_collection.c`
  - `AMDUAT_ASL_COLLECTION_ERR_IO` comes from `amduat_asl_log_append(...)` failure
- `vendor/amduat-api/vendor/amduat/src/core/asl_log_store.c`
  - failure likely in pointer/log append path (`pointer_get`, `store_get`, or `pointer_cas`)

## Targeted Upstream Patch Path

1. Add temporary diagnostic logging in `amduat_asl_log_append(...)` for:
   - `pointer_name`
   - `ptr_err` from `amduat_asl_pointer_get`
   - `store_err` from `amduat_asl_store_get` / `amduat_asl_store_put`
   - `cas_err` and retry exhaustion path
2. Re-run the minimal repro above and capture the first non-OK internal return.
3. Patch the specific failing branch in `asl_log_store.c` (or lower index store path)
   rather than adding retries in app code.
4. Restore/commit missing graph index append scripts expected by CTest:
   - `vendor/amduat-api/scripts/test_graph_index_append.sh`
   - `vendor/amduat-api/scripts/test_graph_index_append_stress.sh`