design: the ecosystem consumer resolves for three targets on the released engine

Section 13.3 recorded one target. The release changes what `[xlings]` accepts
and when a runner is consulted, and neither is target-scoped, so the criterion
that it narrowed nothing has to name more than the target it was written for.

Author: speak-agent

.agents/docs/2026-09-02-runner-beyond-baremetal-design.md

@@ -908,6 +908,16 @@ fails when something is thrown, so a destructor run during the unwind is what
 separates the two. It answers `yes` under the emulator, which means the runner
 carried a working C++ runtime rather than merely starting the process.
 
+The same consumer was then built for three targets from the same SubOS, to
+establish that the release did not narrow what the ecosystem resolves:
+
+```
+x86_64-linux:        BUILD-OK
+aarch64-linux-musl:  BUILD-OK
+x86_64-windows-gnu:  BUILD-OK
+host run:            RUN-OK
+```
+
 ### 13.4 Release state
 
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