refactor(query): deepen command/dispatch seams and resolve coderabbit findings

* refactor(query): deepen command definition seam and fold fallback mapping cleanup

* refactor(query): add shared dispatch formatting module seam

* fix(query): restore QueryResult type import in dispatch deps

* test/query: align raw-output policy and definition normalization contracts

* refactor(query): deepen diagnosis, invariant report, and error taxonomy seams

* refactor(query): deepen dispatch plan, fallback bridge, policy snapshot, and hints seams

* refactor(query): deepen validation, fallback policy, capability, and result builder seams

* refactor(query): deepen resolution strategy, output classifier, observability, and policy-capability seams

* refactor(query): finalize deep strategy/classifier/observability/capability seams

* test/query: address coderabbit inline and out-of-diff dispatch nits

* fix(query): address remaining coderabbit input-validation and bridge stderr threads

* fix(query): address remaining coderabbit dispatch and strategy/output nits

sdk/src/query/query-command-diagnosis.ts

@@ -0,0 +1,32 @@
+import { explainQueryCommandNoMatch, type QueryCommandRegistryLike } from './query-command-semantics.js';
+import { UNKNOWN_COMMAND_HINTS } from './query-unknown-command-hints.js';
+import { describeFallbackDisabledPolicy } from './query-fallback-policy.js';
+
+export interface UnknownCommandDiagnosis {
+  normalized: string;
+  attempted: string[];
+  hints: string[];
+  message: string;
+}
+
+export function diagnoseUnknownCommand(
+  command: string,
+  args: string[],
+  registry: QueryCommandRegistryLike,
+  fallbackRestricted: boolean,
+): UnknownCommandDiagnosis {
+  const noMatch = explainQueryCommandNoMatch(command, args, registry);
+  const normalized = [noMatch.normalized.command, ...noMatch.normalized.args].join(' ');
+  const attempted = noMatch.attempted.dotted.slice(0, 2);
+  const hints = [...UNKNOWN_COMMAND_HINTS];
+  const attemptedSuffix = attempted.length > 0 ? ` Attempted dotted: ${attempted.join(' | ')}.` : '';
+  const fallbackClause = fallbackRestricted ? `${describeFallbackDisabledPolicy()} ` : '';
+  const message = `Error: Unknown command: "${normalized}". ${hints[0]} ${hints[1]} ${fallbackClause}${hints[2]}${attemptedSuffix}`;
+
+  return {
+    normalized,
+    attempted,
+    hints,
+    message,
+  };
+}