Make interaction-manifest behaviour strings match what their tests prove

Sixteen fixes on sixteen entries, each evidenced against the bound test body
or the spec text: narrow over-claiming strings to the assertions that exist
(403-scope-upgrade's unproven no-loop clause, iss mismatch-only coverage,
tools-only registration, arrival-only HTTP notification delivery, the
custom-client auth clause), correct two entries that attributed the modern
classifier's version rejection to the legacy transport, record the 2026
per-request logLevel gate divergence on the Context logging helper and the
list-vs-object structured-content gap on text-mirror, re-ground the null-id
deferral on the now-existing fault channel, and fix the discover result
field name (supportedVersions) plus the 404 status the spec mandates for
initialize at the modern entry. Cells unchanged (830 before and after).

Author: maxisbey

tests/interaction/_requirements.py

@@ -383,10 +383,15 @@ def __post_init__(self) -> None:
         source=f"{SPEC_2026_BASE_URL}/basic#_meta",
         behavior=(
             "Every client→server request on a modern-negotiated session carries "
-            "_meta.{protocolVersion,clientInfo,clientCapabilities}; notifications do not."
+            "_meta.{protocolVersion,clientInfo,clientCapabilities}."
         ),
         added_in="2026-07-28",
         supersedes=("lifecycle:initialize:client-info", "lifecycle:initialize:client-capabilities"),
+        note=(
+            "The spec MUST covers requests only. The session's modern stamp is message-agnostic, so "
+            "session-sent notifications carry the envelope too, while dispatcher-built frames (the "
+            "courtesy cancel) do not; neither notification arm is asserted here."
+        ),
     ),
     "lifecycle:envelope:header-matches-meta": Requirement(
         source=f"{SPEC_2026_BASE_URL}/basic/transports/streamable-http#protocol-version-header",
@@ -415,18 +420,25 @@ def __post_init__(self) -> None:
     "lifecycle:discover:fallback-method-not-found": Requirement(
         source=f"{SPEC_2026_BASE_URL}/basic/transports/stdio#backward-compatibility",
         behavior=(
-            "When server/discover returns any JSON-RPC error or a bare HTTP 4xx, an auto-negotiating "
-            "client falls back to the legacy initialize handshake and the connection succeeds at a "
-            "handshake-era version (legacy servers reject the probe with various codes)."
+            "When server/discover returns a JSON-RPC error that is not a recognized modern negotiation "
+            "error (-32022 retries or raises instead; see lifecycle:discover:retry-on-32022), or a bare "
+            "HTTP 4xx, an auto-negotiating client falls back to the legacy initialize handshake and the "
+            "connection succeeds at a handshake-era version; the fallback is not keyed to specific codes "
+            "(legacy servers reject the probe with various codes)."
         ),
         added_in="2026-07-28",
+        note=(
+            "The SDK keys its no-fallback carve-out to -32022 alone, while the spec's carve-out is any "
+            "recognized modern JSON-RPC error (an open set); no test drives a modern-error probe "
+            "rejection other than -32022."
+        ),
     ),
     "lifecycle:discover:network-error-raises": Requirement(
         source="sdk",
         behavior=(
             "A network/connection error during server/discover propagates to the caller without "
-            "falling back to initialize; any rpc-error or 4xx falls back (legacy servers reject the "
-            "probe with various codes). An outage is never an era verdict."
+            "falling back to initialize; fallback is reserved for server rejections (see "
+            "lifecycle:discover:fallback-method-not-found). An outage is never an era verdict."
         ),
         transports=("streamable-http", "streamable-http-stateless"),
         added_in="2026-07-28",
@@ -655,14 +667,15 @@ def __post_init__(self) -> None:
             note=(
                 "The dispatcher drops null-id error responses with a debug log; in v1, JSONRPCError.id was "
                 "non-nullable, so a null-id error response failed transport validation and the resulting "
-                "ValidationError was surfaced to message_handler as an exception. A typed fault channel "
-                "restoring visibility is planned before v2 stable."
+                "ValidationError was surfaced to message_handler as an exception. The v2 fault channel "
+                "exists (message_handler receives stream exceptions), but response routing drops the "
+                "null-id error before anything reaches it."
             ),
         ),
         deferred=(
             "Not yet covered here: the current drop is pinned at the dispatcher level by "
-            "tests/shared/test_jsonrpc_dispatcher.py; an interaction-level test waits on the planned "
-            "fault channel."
+            "tests/shared/test_jsonrpc_dispatcher.py; an interaction-level test waits on the dispatcher "
+            "routing null-id errors into the existing fault channel."
         ),
     ),
     "protocol:meta:related-task": Requirement(
@@ -893,6 +906,13 @@ def __post_init__(self) -> None:
     "tools:call:structured-content:text-mirror": Requirement(
         source=f"{SPEC_BASE_URL}/server/tools#structured-content",
         behavior="A tool returning structured content also returns the serialized JSON as a text content block.",
+        divergence=Divergence(
+            note=(
+                "Holds for object returns (the bound test pins the serialized-JSON mirror); a "
+                "list-returning tool yields one text block per element rather than the serialized JSON "
+                "of its structured value (pinned by the test on mcpserver:tool:output-schema:wrapped)."
+            ),
+        ),
     ),
     "tools:call:unknown-name": Requirement(
         source=f"{SPEC_BASE_URL}/server/tools#error-handling",
@@ -1094,6 +1114,13 @@ def __post_init__(self) -> None:
             "The Context logging helpers (debug/info/warning/error) send log message notifications at the "
             "corresponding severity."
         ),
+        divergence=Divergence(
+            note=(
+                "At 2026-07-28 the spec forbids notifications/message for a request whose _meta lacks the "
+                "io.modelcontextprotocol/logLevel opt-in; the Context helpers never read that key and emit "
+                "unconditionally, so a bound test pins the un-gated delivery on the live 2026-07-28 cells."
+            ),
+        ),
     ),
     "mcpserver:context:progress": Requirement(
         source="sdk",
@@ -1435,7 +1462,7 @@ def __post_init__(self) -> None:
         behavior="prompts/get for a name that was never registered returns JSON-RPC error -32602 (Invalid params).",
         divergence=Divergence(
             note=(
-                "The spec's example uses -32602 Invalid params for unknown prompts; MCPServer raises "
+                "The spec SHOULD-lists -32602 Invalid params for an invalid prompt name; MCPServer raises "
                 "ValueError, which the low-level server converts to error code 0."
             ),
         ),
@@ -2122,9 +2149,8 @@ def __post_init__(self) -> None:
     "mcpserver:register:post-connect": Requirement(
         source="sdk",
         behavior=(
-            "A tool, resource, or prompt registered or removed after the client connected appears in (or "
-            "disappears from) the corresponding list results, and the change is announced with a "
-            "list_changed notification."
+            "A tool registered or removed after the client connected appears in (or disappears from) "
+            "tools/list results, and the change is announced with a list_changed notification."
         ),
         divergence=Divergence(
             note=(
@@ -2576,8 +2602,7 @@ def __post_init__(self) -> None:
     "transport:streamable-http:notifications": Requirement(
         source=f"{SPEC_BASE_URL}/basic/transports#streamable-http",
         behavior=(
-            "Notifications emitted during a request are delivered on that request's SSE stream and reach "
-            "the client's callbacks, in order, before the response."
+            "Notifications emitted during a request reach the client's callbacks over the streamable HTTP framing."
         ),
         transports=("streamable-http",),
         note="Only observable over streamable HTTP: per-request SSE streams are HTTP-specific.",
@@ -3190,8 +3215,9 @@ def __post_init__(self) -> None:
     "hosting:http:protocol-version-rejection-literal": Requirement(
         source="sdk",
         behavior=(
-            "The legacy streamable-HTTP transport's version-rejection body contains the literal substring "
-            "'Unsupported protocol version', which other-SDK clients substring-match during negotiation."
+            "The streamable-HTTP version-rejection body contains the literal substring 'Unsupported "
+            "protocol version', which other-SDK clients substring-match during negotiation; the modern "
+            "request classifier is its only emission site."
         ),
         transports=("streamable-http",),
         note=(
@@ -3233,17 +3259,18 @@ def __post_init__(self) -> None:
     ),
     "hosting:http:modern:initialize-removed": Requirement(
         source=f"{SPEC_2026_BASE_URL}/basic/index",
-        behavior="A 2026-07-28 initialize request is answered with METHOD_NOT_FOUND.",
+        behavior="A 2026-07-28 initialize request is answered with METHOD_NOT_FOUND at HTTP 404.",
         added_in="2026-07-28",
         transports=("streamable-http",),
         note=("Only observable over streamable HTTP: the modern entry's method registry omits initialize."),
     ),
     "hosting:http:modern:legacy-fallthrough": Requirement(
         source=f"{SPEC_2026_BASE_URL}/basic/versioning",
         behavior=(
-            "Non-2026-07-28 traffic on the same /mcp endpoint reaches the legacy transport "
-            "byte-unchanged: a 2025-era initialize handshake still completes, and an unrecognised "
-            "MCP-Protocol-Version header still produces the legacy 400 'Unsupported protocol version' literal."
+            "Initialize-handshake-era traffic on the same /mcp endpoint reaches the legacy transport "
+            "byte-unchanged: a 2025-era initialize handshake still completes. Any other "
+            "MCP-Protocol-Version header routes to the modern entry, whose validation ladder rejects "
+            "the envelope-less request with 400 INVALID_PARAMS."
         ),
         added_in="2026-07-28",
         transports=("streamable-http",),
@@ -3388,10 +3415,7 @@ def __post_init__(self) -> None:
     ),
     "client-transport:http:custom-client": Requirement(
         source="sdk",
-        behavior=(
-            "A caller-supplied HTTP client (and its event hooks and headers) is used for all MCP traffic, "
-            "including auth flows."
-        ),
+        behavior="A caller-supplied HTTP client (and its event hooks and headers) is used for all MCP traffic.",
         transports=("streamable-http",),
         note="Only observable over HTTP: the httpx2 client is HTTP-specific.",
     ),
@@ -3563,9 +3587,7 @@ def __post_init__(self) -> None:
     ),
     "client-auth:403-scope-upgrade": Requirement(
         source=f"{SPEC_BASE_URL}/basic/authorization#step-up-authorization-flow",
-        behavior=(
-            "A 403 with WWW-Authenticate triggers a scope-upgrade authorization attempt; repeated 403s do not loop."
-        ),
+        behavior="A 403 with WWW-Authenticate triggers a scope-upgrade authorization attempt.",
         transports=("streamable-http",),
         note="OAuth is HTTP-only.",
     ),
@@ -3812,8 +3834,7 @@ def __post_init__(self) -> None:
         source=f"{SPEC_2026_BASE_URL}/basic/authorization#authorization-response-validation",
         behavior=(
             "The client validates the RFC 9207 iss authorization-response parameter against the "
-            "authorization server issuer (simple string comparison) and rejects a mismatch, or a "
-            "missing iss when the server advertises support (SEP-2468)."
+            "authorization server issuer (simple string comparison) and rejects a mismatch (SEP-2468)."
         ),
         added_in="2026-07-28",
         transports=("streamable-http",),