Verify native behavior creation recovery and source authoring contracts

docs/language.html

@@ -752,7 +752,7 @@ lists all additional fields. <span class="docutils literal">ref</span> means <sp
 </tr>
 <tr><td><p><span class="docutils literal">oa_scenario</span>, <span class="docutils literal">sa_scenario</span></p></td>
 <td><p><span class="docutils literal">viewpoint</span>: ScenarioViewpoint; <span class="docutils literal">context</span>: ref?; <span class="docutils literal">precondition</span>, <span class="docutils literal">postcondition</span>: strings; <span class="docutils literal">steps</span>: occurrence refs</p></td>
-<td><p>MixedLegacy for omitted schema-2 source; none; <span class="docutils literal">&quot;&quot;</span>; <span class="docutils literal">&quot;&quot;</span>; <span class="docutils literal">[]</span></p></td>
+<td><p>MixedLegacy when viewpoint is omitted, including newly authored source 7 (see section 4.3); none; <span class="docutils literal">&quot;&quot;</span>; <span class="docutils literal">&quot;&quot;</span>; <span class="docutils literal">[]</span></p></td>
 </tr>
 <tr><td><p><span class="docutils literal">oa_lifeline</span>, <span class="docutils literal">sa_lifeline</span></p></td>
 <td><p><span class="docutils literal">represented</span>: participant, work, or role ref?</p></td>
@@ -792,49 +792,71 @@ An Enumeration contains unique string literals. For example:</p>
 <pre class="code text literal-block"><code>definition { Enumeration { literals [&quot;Clear&quot;, &quot;Fog&quot;]; }; };
 type_ref { Named &#64;weather_classification; };</code></pre>
 <p>These are typed constructors with named fields, not embedded JSON documents.
-Constructor field names and enum spellings are case-sensitive. When replacing
-a constructor, all of its fields MUST be supplied; the containing declaration
-defaults do not silently fill a different constructor's missing fields.
-During schema-2 compatibility, the new Exchange fields <span class="docutils literal">message_kind</span>,
-<span class="docutils literal">reply_to</span> and <span class="docutils literal">values</span> are exceptions: omitted values hydrate as
-Asynchronous, none and [] respectively. Canonical output writes them explicitly.
-This preserves older schema-2 source/JSON without inventing call correlation or
-value annotations. It is not a rule for an unspecified future schema.</p>
+Constructor field names and enum spellings are case-sensitive. A selected
+constructor uses its own field contract; it does not inherit the payload of a
+different constructor from the declaration default. Required fields MUST be
+supplied. Nullability and omission are separate properties: <span class="docutils literal">?</span> denotes a
+value that can be <span class="docutils literal">none</span>; a constructor's omission contract determines whether
+the field may be absent. There is no general all-constructor-fields-required
+rule. Other typed constructors use their contracts in the corresponding
+sections; the occurrence rules below do not establish defaults for them.</p>
+<p>The following table records the source-7 OccurrenceBody contracts. Optional
+references may be omitted and then mean <span class="docutils literal">none</span>. Exchange also admits omitted
+<span class="docutils literal">message_kind</span> and <span class="docutils literal">values</span>, meaning Asynchronous and <span class="docutils literal">[]</span> respectively.
+These omissions are accepted in newly authored source 7, not only in schema-2
+compatibility input. Earlier schema admission of constructors and fields is
+still governed by its version rules.</p>
+<p>Canonical formatting writes the hydrated occurrence references and default
+<span class="docutils literal">message_kind</span>, <span class="docutils literal">reply_to</span> and <span class="docutils literal">values</span> explicitly. An absent
+<span class="docutils literal">operation</span> remains omitted in canonical output. Lossless no-op updates and
+unrelated name edits retain authored omissions; canonical formatting is a
+different operation. An admitted incomplete occurrence can still produce model
+checks requesting its missing work, exchange, lifeline or referenced scenario.</p>
 <table>
 <caption>Occurrence body constructors</caption>
 <colgroup>
-<col style="width: 22.0%" />
-<col style="width: 78.0%" />
+<col style="width: 18.0%" />
+<col style="width: 36.0%" />
+<col style="width: 46.0%" />
 </colgroup>
 <thead>
 <tr><th class="head"><p>Constructor</p></th>
 <th class="head"><p>Required fields</p></th>
+<th class="head"><p>Fields that may be omitted, with their resulting values</p></th>
 </tr>
 </thead>
 <tbody>
 <tr><td><p>Exchange</p></td>
-<td><p><span class="docutils literal">exchange</span>: exchange relation ref?; <span class="docutils literal">sender</span>, <span class="docutils literal">receiver</span>: lifeline refs?; <span class="docutils literal">message_kind</span>: MessageKind; <span class="docutils literal">reply_to</span>: occurrence ref?; <span class="docutils literal">values</span>: MessageValue records</p></td>
+<td><p>None</p></td>
+<td><p><span class="docutils literal">exchange</span>: exchange relation ref?, <span class="docutils literal">sender</span>, <span class="docutils literal">receiver</span>: lifeline refs?, <span class="docutils literal">reply_to</span>: occurrence ref?, <span class="docutils literal">operation</span>: OperationUse? → <span class="docutils literal">none</span>; <span class="docutils literal">message_kind</span>: MessageKind → Asynchronous; <span class="docutils literal">values</span>: MessageValue records → <span class="docutils literal">[]</span></p></td>
 </tr>
 <tr><td><p>Action</p></td>
-<td><p><span class="docutils literal">action</span>: activity/function ref?; <span class="docutils literal">lifeline</span>: ref?</p></td>
+<td><p>None</p></td>
+<td><p><span class="docutils literal">action</span>: activity/function ref?, <span class="docutils literal">lifeline</span>: ref? → <span class="docutils literal">none</span></p></td>
 </tr>
 <tr><td><p>Control</p></td>
 <td><p><span class="docutils literal">kind</span>: Choice, Merge, Fork, Join, Loop</p></td>
+<td><p>None</p></td>
 </tr>
 <tr><td><p>SequenceReference</p></td>
-<td><p><span class="docutils literal">sequence</span>: process/functional-chain ref?</p></td>
+<td><p>None</p></td>
+<td><p><span class="docutils literal">sequence</span>: process/functional-chain ref? → <span class="docutils literal">none</span></p></td>
 </tr>
 <tr><td><p>ScenarioUse</p></td>
-<td><p><span class="docutils literal">scenario</span>: scenario ref?; <span class="docutils literal">bindings</span>: LifelineBinding records</p></td>
+<td><p><span class="docutils literal">bindings</span>: LifelineBinding records</p></td>
+<td><p><span class="docutils literal">scenario</span>: scenario ref? → <span class="docutils literal">none</span></p></td>
 </tr>
 <tr><td><p>State</p></td>
-<td><p><span class="docutils literal">state</span>: state/mode ref?; <span class="docutils literal">lifeline</span>: ref?</p></td>
+<td><p>None</p></td>
+<td><p><span class="docutils literal">state</span>: state/mode ref?, <span class="docutils literal">lifeline</span>: ref? → <span class="docutils literal">none</span></p></td>
 </tr>
 <tr><td><p>Fragment</p></td>
 <td><p><span class="docutils literal">operator</span>: Alternative, Parallel, Loop, Optional; <span class="docutils literal">branches</span>: branch occurrence refs</p></td>
+<td><p>None</p></td>
 </tr>
 <tr><td><p>Branch</p></td>
 <td><p><span class="docutils literal">guard</span>: string; <span class="docutils literal">occurrences</span>: occurrence refs</p></td>
+<td><p>None</p></td>
 </tr>
 </tbody>
 </table>