feat(streams): add HDSModelStreams.isContext() helper (plan 53 phase A)

Surfaces the new data-model `role: context` flag at the runtime layer. Returns
true iff a stream definition has role === 'context' (i.e. it's a descendant-
streamId marker for D3 context-via-substream resolution, not a data-bearing
bucket). Unknown streamIds return false — this is a yes/no probe, no throw.

Consumers (settings trees, form-section renderers, dashboards) should use
this to elide / mute / re-render context streams as metadata rather than as
independent input streams. D3 walk-up resolution (forEvent) is unaffected by
the flag.

4 new tests [CTXR-P/Q/R/S] in tests/contextResolution.test.js validate against
the locally-built data-model pack.json so the flag is sourced from real YAML.

Pairs with healthdatasafe/data-model#17 (role: context added to
treatment-fertility and procedure-fertility).

Author: perki

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## [Unreleased]
+
+### Added (plan 53 phase A — `HDSModelStreams.isContext()` helper)
+- `HDSModelStreams#isContext(streamId): boolean` — returns `true` iff the stream's data-model definition carries `role: 'context'` (the D3 descendant-streamId marker flag introduced in `@hds/data-model` Plan 53 Phase A). Unknown streamIds return `false` (no throw).
+- Use this to elide / mute / re-render context streams as metadata in settings trees, form-section renderers, and dashboards rather than as data-bearing buckets. Runtime resolution (`itemsDefs.forEvent` walk-up) is unaffected.
+- Tests: `[CTXR-P/Q/R/S]` in `tests/contextResolution.test.js`. Validates against the locally-built `data-model/dist/pack.json` so the flag is sourced from real YAML.
+
 ## [1.0.0] - 2026-05-27
 
 ### Plan 61 Phase C — legacy collector code deleted

tests/contextResolution.test.js

@@ -104,6 +104,25 @@ describe('[CTXR] Context-via-substream (Plan 46 D3)', () => {
     });
   });
 
+  describe('isContext() — Plan 53 role: context flag', () => {
+    it('[CTXR-P] treatment-fertility is flagged as context', () => {
+      assert.equal(model.streams.isContext('treatment-fertility'), true);
+    });
+
+    it('[CTXR-Q] procedure-fertility is flagged as context', () => {
+      assert.equal(model.streams.isContext('procedure-fertility'), true);
+    });
+
+    it('[CTXR-R] data-bearing parent streams are not context', () => {
+      assert.equal(model.streams.isContext('treatment'), false);
+      assert.equal(model.streams.isContext('procedure'), false);
+    });
+
+    it('[CTXR-S] unknown streamId returns false (no throw)', () => {
+      assert.equal(model.streams.isContext('no-such-stream'), false);
+    });
+  });
+
   describe('legacy multi-streamId resolution still works (no regression)', () => {
     it('[CTXR-K] event with multiple streamIds resolves via direct match', () => {
       // bridge-athenahealth pattern: streamIds carry both the canonical home

ts/HDSModel/HDSModel-Streams.ts

@@ -76,6 +76,21 @@ export class HDSModelStreams {
     return streamData;
   }
 
+  /**
+   * True iff the stream exists and its data-model definition carries
+   * `role: 'context'` — i.e. it's a descendant-streamId marker for the D3
+   * context-via-substream mechanic, not a data-bearing bucket. Unknown
+   * streamIds return `false` (no throw — this is a yes/no probe).
+   *
+   * Consumers (settings trees, form-section renderers, dashboards) should
+   * use this to elide / mute / re-render context streams as metadata rather
+   * than as independent input streams. See Plan 53.
+   */
+  isContext (streamId: string): boolean {
+    const streamData = this.#modelStreamsById[streamId];
+    return streamData != null && streamData.role === 'context';
+  }
+
   /**
    * Get all parents id;
    */