Record two divergences as intentional, ecosystem-consistent choices

Two interaction-suite divergence notes described their gaps as
unenforced spec MUSTs without saying whether closing them was planned.
Both are deliberate, and the notes now say so.

transport:stdio:stream-purity -- stdio_server does not redirect
sys.stdout, so a handler print() corrupts the protocol stream. No MCP
SDK redirects stdout, and a redirect would only catch print(), not
os.write(1, ...) or C extensions writing to file descriptor 1, so it
would be a partial guard rather than a structural fix.
docs/tutorial/logging.md already tells server authors to log to stderr
and never print() in a stdio server, so no docs change was needed.

protocol:progress:monotonic -- no MCP SDK validates sender-side
progress monotonicity; the spec MUST is a contract on the handler
author, not on the transport, and the test pins the unvalidated
pass-through.

No code or test behaviour changes.

Author: maxisbey

tests/interaction/_requirements.py

@@ -668,10 +668,11 @@ def __post_init__(self) -> None:
         divergence=Divergence(
             note=(
                 "Intentional, not a gap to close: no MCP SDK (typescript, go, csharp) validates "
-                "sender-side progress monotonicity, and this one does not either. The spec MUST "
-                "binds the handler author, not the transport; non-increasing values are forwarded "
-                "to the callback unchanged so the receiving application sees what the sender sent. "
-                "docs/tutorial/progress.md states the author's obligation."
+                "sender-side progress monotonicity, and this one does not either. The spec MUST is "
+                "a contract on the handler author, not on the transport; non-increasing values are "
+                "forwarded to the callback unchanged so the receiving application sees what the "
+                "sender sent, and the test pins that pass-through. docs/tutorial/progress.md "
+                "states the author's obligation."
             ),
         ),
         known_failures=(
@@ -3626,9 +3627,13 @@ def __post_init__(self) -> None:
         note="Only observable over stdio: stdin/stdout purity is stdio-specific.",
         divergence=Divergence(
             note=(
-                "stdio_server's own writes satisfy this, but it does not redirect or guard sys.stdout: "
-                "handler code that calls print() writes directly to the protocol stream and corrupts the "
-                "framing. The spec MUST is satisfied only as long as application code behaves."
+                "Intentional, not a gap to close: the SDK's own writes are pure, but sys.stdout is not "
+                "redirected, so handler code that calls print() writes into the protocol stream and "
+                "corrupts the framing. This matches every other MCP SDK -- none redirects stdout. A "
+                "redirect would only catch print(): os.write(1, ...) and C extensions that write to file "
+                "descriptor 1 bypass sys.stdout entirely, so it would be a partial guard rather than a "
+                "structural fix. docs/tutorial/logging.md tells server authors to log to stderr and "
+                "never print() in a stdio server."
             ),
         ),
     ),