Document subprocess run results

docs/internal/cli.md

@@ -84,6 +84,16 @@ final command result. Detailed state lifecycle, resume handling, and physical
 path confinement are maintained in [Run State Internals](state.md) and
 [Operations](../operations.md).
 
+For `run --json`, the CLI constructs and encodes its private run-result receipt
+after a successful runner result is available, before it publishes logical
+output files. It writes the prepared receipt to standard output only after
+output publication and requested debug terminalization succeed. A receipt-write
+failure is a runtime command failure; output may be partial, the CLI reports a
+bounded command-owned error, and it does not repeat terminal reporting. The
+receipt remains a CLI reporting concern rather than a framework or output-module
+responsibility; its public contract is the
+[run-result receipt](../integrations/run-result.md).
+
 ## Failure Mapping And Terminal Reporting
 
 Argument, flag, and invocation-combination failures are reported to standard