# Native Capella Scenario spacing observation

A bounded primary observation in Capella **7.1.0.202606231255** on Windows, using isolated workspace capella-layout-benchmark-20260912 and project IncidentScenarioBenchmark. The parent integration session performed the authorized Computer/Sky interactions and reports closing Capella normally afterward. This archive's independent reviewer inspected the saved screenshots and files; the reviewer did not perform native input. [observations.json](original/observations.json) retains the operator's actions, timestamps and capture recovery notes.

Scope: one Operational Analysis scenario, two activity lifelines and one interaction. This does not establish chronology-crossing/reordering behavior, activation nesting, or a general Capella gesture policy.

## Observed workflow

| Evidence | Observed result |
| --- | --- |
| [01 empty scenario](original/01-empty-scenario.jpg), [02 lifeline](original/02-created-lifeline.jpg), [03 interaction choice](original/03-interaction-choice.jpg), [04 message](original/04-created-message.jpg) | Created two activity lifelines and one Report incident interaction. Completing the pending interaction used an endpoint click and the Create a new Interaction choice. |
| [05 body drag](original/05-body-drag-no-visible-change.jpg), [06 selected body drag](original/06-selected-body-drag-no-visible-change.jpg) | Two arrow-body drag attempts produced no visible movement, including the attempt after selecting Sequence Message. This does not prove that Capella never supports body movement. |
| [07 receiver execution drag](original/07-execution-drag-moves-message.jpg) | Dragging the small receiver execution down 79 pixels moved the whole horizontal message from screen y334 to y413, with its receiver execution. |
| [08 lifeline header drag](original/08-lifeline-header-drag.jpg) | Moving the left header from screen x430 to x510 moved that lifeline and its attached message endpoint 80 pixels. |
| [09 first Undo](original/09-undo-lifeline.jpg) | One Undo restored the left lifeline to x430 while the message remained at y413. |
| [10 second Undo](original/10-undo-message.jpg) | The next Undo restored the message to y334. After Save, both captured files exactly matched the baseline. |

The operator recorded two capture timeouts: after the first activity placement and after the initial interaction drag. Each was recovered by selecting the returned window afresh and taking another screenshot; the input was not repeated. These failures/recoveries are preserved in observations.json rather than omitted or treated as extra interactions.

## Saved-file comparison

[Before .capella](original/before-drag-IncidentScenarioBenchmark.capella), [after receiver-drag .capella](original/after-drag-IncidentScenarioBenchmark.capella), and [restored .capella](original/restored-IncidentScenarioBenchmark.capella) are byte-identical: 26,594 bytes, SHA-256 d8764060c6f3d11ddf24a91e20955fe035725cfe35019fdd514688d07118c056. Thus this saved move did not alter the captured semantic model file.

The [before .aird](original/before-drag-IncidentScenarioBenchmark.aird) and [after receiver-drag .aird](original/after-drag-IncidentScenarioBenchmark.aird) differ on exactly five lines, with no line insertion/deletion:

| Before-file line | Field change | Interpretation |
| --- | --- | --- |
| 11 | representation changeId changed | Presentation revision metadata. |
| 100 | receiver execution notation bounds y53→132 | +79 vertical placement; width/height unchanged. |
| 125 | message relative bendpoint y offsets 0→79 | Both ends of the existing horizontal path moved vertically. |
| 183 | receiver execution absolute-bounds y153→232 | +79 corresponding presentation filter. |
| 205 | SequenceMessage absolute-bounds y153→232 | +79 corresponding message filter. |

Object references identify the changed execution and Report incident SequenceMessage; [manifest.json](manifest.json) preserves the exact five before/after lines. This is a presentation-file change for the recorded receiver-execution move. No separate saved snapshot was taken after the horizontal header move, so its isolated serialized delta is not claimed.

After both Undos and Save, [restored .aird](original/restored-IncidentScenarioBenchmark.aird) equals before byte-for-byte: 29,469 bytes, SHA-256 c24db589f3a551b8ea0f8d00d2dc6729909157e2a3ac4ebc0ca69cd141393c89. The two separate visible Undo steps and complete saved restoration support the observed local history behavior.

## Integrity and implication

All 27 original evidence artifacts are preserved without content changes: ten screenshots, their ten metadata files, observations and six source snapshots. The screenshots were originally named .png but contain JPEG/JFIF bytes. Published names use .jpg with explicit originalName→path mapping in manifest.json; no transcoding or duplicate image copies occurred. All ten metadata SHA-256 values and encoded 1010×761 dimensions were independently verified. The manifest includes every artifact's byte length, SHA-256 and Git blob SHA-1; local -text attributes preserve source line endings.

This evidence supports separating view-local message/lifeline spacing from shared semantics for this simple case. A Studio gesture should make its target discoverable and separately verify preview/commit equality and one-step Undo. Those are design implications, not Capella-wide behavior or Studio implementation acceptance. The archive is observation evidence, not a packaged benchmark project or native Studio test.