test(#3339): fold the state/phase/dispatch & model-profile issue-* cluster — Wave 7

Folds 9 legacy issue-*.test.cjs regression files (140 test() blocks) into
their module's main suite, per H3 (#3315) of the test-hygiene epic (#3053).
LAST of 4 issue-* waves — closes out the 74-file fix-*/issue-* backlog
(pending BUG_FILE_RE extension, held for a follow-up commit until Wave 6
is confirmed merged, per the epic's own zero-backlog precondition).

- issue-2828-flat-roadmap-total-phases.test.cjs (1) + issue-3204-state-
  writer-phase-count.test.cjs (21): both target state-document.cjs
  buildStateFrontmatter via different CLI entrypoints — merged jointly
  into state-document.test.cjs, 0 dropped.
- issue-2945-phase-complete-checkbox-rollback.test.cjs (4) + issue-2949-
  phase-complete-stage3-sentinel.test.cjs (4): both target phase.cts
  cmdPhaseComplete; issue explicitly warned of overlap — verified
  disjoint fixtures/assertions, 0 dropped, merged into phase.test.cjs.
- issue-2927-reviewer-lane-overlay-invocation.test.cjs (10) merged into
  review-lane-descriptor.test.cjs.
- issue-2939-dispatch-flatten-maxdepth.test.cjs (9) merged into
  host-integration.test.cjs, 2 dropped as verified exact duplicates.
- issue-2977-frontmatter-bom.test.cjs (5) merged into frontmatter.test.cjs.
- issue-2045-third-party-skills-surface.test.cjs (6) merged into
  capability-loader.test.cjs.
- issue-2517-runtime-aware-profiles.test.cjs (80, the largest single
  fold in the epic) merged into model-resolver.test.cjs, 1 dropped as a
  verified true duplicate (checked against src/model-resolver.cts logic,
  not just title similarity).

Fixed a genuine eslint irregular-whitespace finding: a literal BOM
character embedded in a doc comment (pre-existing content from the
original #2977 source, illustrating what a BOM looks like) — replaced
with a readable U+FEFF notation.

3 stale doc references found and fixed (docs/adr/2313, 3180, 443).

Zero net test-coverage loss. No production code changed.

tests/host-integration.test.cjs

@@ -2502,3 +2502,103 @@ describe('#2728 B1 — isolation degrades re-record through the single write pat
     );
   });
 });
+
+// ---------------------------------------------------------------------------
+// Folded from tests/issue-2939-dispatch-flatten-maxdepth.test.cjs (H3 Wave 7,
+// issue #3339). Two of the original nine cases (maxDepth:1 → true and
+// maxDepth:2 → false, both with the full codex-like descriptor) were exact
+// duplicates of the "Phase B: shouldFlattenDispatch — contract pin" describe
+// above (lines ~1014-1029) and were dropped; the remaining seven exercise
+// input shapes (maxDepth:-1 unbounded, nested:false, non-full toolkit,
+// background:false/backgroundDispatch:false with maxDepth:5, maxDepth:0,
+// and maxDepth missing/non-number) not covered elsewhere in this file.
+// ---------------------------------------------------------------------------
+{
+  const { describe: __foldDescribe } = require('node:test');
+  __foldDescribe('folded:issue-2939-dispatch-flatten-maxdepth', () => {
+    /** The live Codex-shaped descriptor (the #2939 bug input), with per-test depth overrides. */
+    function codexLike(overrides = {}) {
+      return {
+        namedDispatch: true,
+        nested: true,
+        maxDepth: 1,
+        background: true,
+        subagentToolkit: 'full',
+        backgroundDispatch: true,
+        ...overrides,
+      };
+    }
+
+    test('maxDepthUnboundedBackgroundsUnchanged', () => {
+      // Row 3: maxDepth:-1 (unbounded) → background permitted, unchanged.
+      assert.strictEqual(
+        hi.shouldFlattenDispatch(codexLike({ maxDepth: -1 })),
+        false,
+        'maxDepth:-1 (unbounded) → background permitted (unchanged)',
+      );
+    });
+
+    test('nestedFalseFlattensRegardlessOfDepth', () => {
+      // Row 4 / acceptance #4: nested:false cannot host a nesting orchestrator →
+      // flatten regardless of maxDepth.
+      assert.strictEqual(
+        hi.shouldFlattenDispatch(codexLike({ nested: false, maxDepth: 5 })),
+        true,
+        'nested:false → flatten regardless of maxDepth',
+      );
+    });
+
+    test('nonFullToolkitFlattens', () => {
+      // Row 5 / acceptance #4: a non-full toolkit cannot delegate → flatten
+      // regardless of maxDepth.
+      assert.strictEqual(
+        hi.shouldFlattenDispatch(codexLike({ subagentToolkit: 'read-only', maxDepth: 5 })),
+        true,
+        'subagentToolkit!=="full" → flatten regardless of maxDepth',
+      );
+    });
+
+    test('backgroundFalseStillFlattens', () => {
+      // Row 6 / negative-space: background:false → flatten (the existing
+      // background-boolean fail-closed path is unchanged).
+      assert.strictEqual(
+        hi.shouldFlattenDispatch(codexLike({ background: false, maxDepth: 5 })),
+        true,
+        'background:false → flatten (unchanged)',
+      );
+    });
+
+    test('backgroundDispatchFalseStillFlattens', () => {
+      // Row 7 / negative-space: backgroundDispatch:false → flatten (unchanged).
+      assert.strictEqual(
+        hi.shouldFlattenDispatch(codexLike({ backgroundDispatch: false, maxDepth: 5 })),
+        true,
+        'backgroundDispatch:false → flatten (unchanged)',
+      );
+    });
+
+    test('maxDepth0Flattens', () => {
+      // Row 9: maxDepth:0 (zero depth budget) → flatten.
+      assert.strictEqual(
+        hi.shouldFlattenDispatch(codexLike({ maxDepth: 0 })),
+        true,
+        'maxDepth:0 → flatten (zero depth budget)',
+      );
+    });
+
+    test('maxDepthMissingFlattens', () => {
+      // Row 10: maxDepth missing/non-number → flatten (fail-closed on absent
+      // budget, mirrors degradationFor treating non-finite as 0).
+      assert.strictEqual(
+        hi.shouldFlattenDispatch(codexLike({ maxDepth: undefined })),
+        true,
+        'maxDepth missing → flatten (fail-closed)',
+      );
+      assert.strictEqual(
+        hi.shouldFlattenDispatch(codexLike({ maxDepth: 'deep' })),
+        true,
+        'maxDepth non-number → flatten (fail-closed)',
+      );
+    });
+  });
+}