docs(protocol): allow Clients to tolerate a/ and b/ prefixes on relative git_patch paths (#2578)

The parsing note said to configure diff parsers not to strip any leading
component. Absolute paths never carry Git's prefixes, so stripping only matters
for relative paths, which already come from Agents that don't follow the rules.
Say not to strip from absolute paths, and that Clients can still strip a/ or b/
from relative paths to tolerate Git's default output while changes decides the
file.

Author: benbrandt

docs/protocol/v2/draft/tool-calls.mdx

@@ -594,9 +594,12 @@ Git can produce most of this. With `$ROOT` set to the repository root,
 repository root prepended, with Git's quoting applied to the full path.
 
 Many diff parsers strip one leading path component by default to remove Git's
-`a/` and `b/` prefixes, so configure them not to strip any. Take paths from
-`changes`, or from the `---`, `+++`, rename, and copy lines, rather than by
-splitting the `diff --git` header, which is ambiguous when paths contain spaces.
+`a/` and `b/` prefixes. Don't strip anything from an absolute path, which has no
+such prefix. A Client can still strip a leading `a/` or `b/` from a relative
+path to tolerate Agents that send Git's default output, as long as `changes`
+decides which file a patch belongs to. Take paths from `changes`, or from the
+`---`, `+++`, rename, and copy lines, rather than by splitting the `diff --git`
+header, which is ambiguous when paths contain spaces.
 
 </ParamField>
 

docs/protocol/v2/tool-calls.mdx

@@ -594,9 +594,12 @@ Git can produce most of this. With `$ROOT` set to the repository root,
 repository root prepended, with Git's quoting applied to the full path.
 
 Many diff parsers strip one leading path component by default to remove Git's
-`a/` and `b/` prefixes, so configure them not to strip any. Take paths from
-`changes`, or from the `---`, `+++`, rename, and copy lines, rather than by
-splitting the `diff --git` header, which is ambiguous when paths contain spaces.
+`a/` and `b/` prefixes. Don't strip anything from an absolute path, which has no
+such prefix. A Client can still strip a leading `a/` or `b/` from a relative
+path to tolerate Agents that send Git's default output, as long as `changes`
+decides which file a patch belongs to. Take paths from `changes`, or from the
+`---`, `+++`, rename, and copy lines, rather than by splitting the `diff --git`
+header, which is ambiguous when paths contain spaces.
 
 </ParamField>