# C891 — Checkpoint the partial-action explanation

## Question

What does the60-action prefix add to the Strategy model?

## Inputs

```json
{}
```

## Sources

```json
[
  "C832–890"
]
```

## Opened utc

2026-09-28T02:51:11.748774+00:00

## Results

```json
{
  "checkpoint": {
    "path": "deliverables/490d_Chronological_Families_Checkpoint_C891.md",
    "sha256": "9dd481ca60ab6312e0c0017f79d58d641e75060d7ed38f9d278a71da8c450469",
    "bytes": 1380
  },
  "prefix": 59
}
```

## Finding

The Key family is now explained as exact partial action on declared grids and anchored paths. The next whole-family test can distinguish outer expansion from retention of an internal biography.

## Reassessment

Reconstruct the complete six-row macrohead field.

## Checks

```json
{
  "prefix59": true,
  "last890": true
}
```

## Closed utc

2026-09-28T02:51:11.749925+00:00

## Record provenance

Exact record hash: `53dae8ddea2ab9d721f470ed91ede57a5406f773c2170dcb2a18293946f0034d`

Source journal: `Research_Cycles/C0832_C0931/journal.json`