diff --git a/dotnet/test/E2E/SessionE2ETests.cs b/dotnet/test/E2E/SessionE2ETests.cs
index bcc8fc268..17658d78f 100644
--- a/dotnet/test/E2E/SessionE2ETests.cs
+++ b/dotnet/test/E2E/SessionE2ETests.cs
@@ -332,10 +332,10 @@ await session.SendAsync(new MessageOptions
         // Verify an abort event exists in messages
         Assert.Contains(messages, m => m is AbortEvent);
 
-        // We should be able to send another message
-        var answer = await session.SendAndWaitAsync(new MessageOptions { Prompt = "What is 2+2?" });
-        Assert.NotNull(answer);
-        Assert.Contains("4", answer!.Data.Content ?? string.Empty);
+        await session.SendAsync(new MessageOptions { Prompt = "What is 2+2?" });
+        var recoveryMessage = await TestHelper.GetFinalAssistantMessageAsync(session);
+        Assert.NotNull(recoveryMessage);
+        Assert.Contains("4", recoveryMessage.Data.Content ?? string.Empty);
     }
 
     [Fact]
diff --git a/dotnet/test/Harness/E2ETestContext.cs b/dotnet/test/Harness/E2ETestContext.cs
index c01f4efcf..809ab55a3 100644
--- a/dotnet/test/Harness/E2ETestContext.cs
+++ b/dotnet/test/Harness/E2ETestContext.cs
@@ -5,6 +5,7 @@
 using Microsoft.Extensions.Logging;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 using System.Text.RegularExpressions;
 
 namespace GitHub.Copilot.Test.Harness;
@@ -141,20 +142,40 @@ private static string GetCliPath(string repoRoot)
         if (!string.IsNullOrEmpty(envPath)) return envPath;
 
         // As of CLI 1.0.64-1 the @github/copilot package is a thin loader; the
-        // runnable index.js ships in the installed platform package
-        // (e.g. @github/copilot-linux-x64). Exactly one is installed.
+        // runnable index.js ships in the installed platform package.
         var githubModules = Path.Join(repoRoot, "nodejs", "node_modules", "@github");
-        if (Directory.Exists(githubModules))
+        var packagePrefix = GetCliPackagePrefix();
+        var candidates = Directory.Exists(githubModules)
+            ? Directory.EnumerateDirectories(githubModules, $"{packagePrefix}-*", SearchOption.TopDirectoryOnly)
+                .Select(directory => Path.Join(directory, "index.js"))
+                .Where(File.Exists)
+                .ToArray()
+            : [];
+
+        return candidates.Length switch
         {
-            var candidate = Directory.EnumerateDirectories(githubModules, "copilot-*")
-                .Select(dir => Path.Join(dir, "index.js"))
-                .FirstOrDefault(File.Exists);
-            if (candidate != null)
-                return candidate;
-        }
+            1 => candidates[0],
+            0 => throw new InvalidOperationException(
+                $"CLI package matching '{packagePrefix}-*' not found under {githubModules}. " +
+                "Run 'npm install' in the nodejs directory first."),
+            _ => throw new InvalidOperationException(
+                $"Multiple CLI packages matching '{packagePrefix}-*' found under {githubModules}: " +
+                string.Join(", ", candidates.Select(Path.GetDirectoryName))),
+        };
+    }
 
-        throw new InvalidOperationException(
-            $"CLI not found under {githubModules}. Run 'npm install' in the nodejs directory first.");
+    private static string GetCliPackagePrefix()
+    {
+        var platform = OperatingSystem.IsWindows()
+            ? "win32"
+            : OperatingSystem.IsMacOS()
+                ? "darwin"
+                : OperatingSystem.IsLinux()
+                    ? RuntimeInformation.RuntimeIdentifier.StartsWith("linux-musl-", StringComparison.Ordinal)
+                        ? "linuxmusl"
+                        : "linux"
+                    : throw new PlatformNotSupportedException("Unsupported operating system for Copilot CLI E2E tests.");
+        return $"copilot-{platform}";
     }
 
     public async Task ConfigureForTestAsync(string testFile, [CallerMemberName] string? testName = null)
diff --git a/python/README.md b/python/README.md
index 3089c3669..2ae6f41bf 100644
--- a/python/README.md
+++ b/python/README.md
@@ -76,6 +76,7 @@ from copilot import CopilotClient
 from copilot.session_events import AssistantMessageData, SessionIdleData
 from copilot.session import PermissionHandler
 
+
 async def main():
     # Client automatically starts on enter and cleans up on exit
     async with CopilotClient() as client:
@@ -100,6 +101,7 @@ async def main():
             await session.send("What is 2+2?")
             await done.wait()
 
+
 asyncio.run(main())
 ```
 
@@ -114,6 +116,7 @@ from copilot import CopilotClient
 from copilot.session_events import AssistantMessageData, SessionIdleData
 from copilot.session import PermissionHandler
 
+
 async def main():
     client = CopilotClient()
     await client.start()
@@ -141,6 +144,7 @@ async def main():
     await session.disconnect()
     await client.stop()
 
+
 asyncio.run(main())
 ```
 
@@ -167,6 +171,7 @@ async with CopilotClient() as client:
         on_permission_request=PermissionHandler.approve_all,
         model="gpt-5",
     ) as session:
+
         def on_event(event):
             print(f"Event: {event.type}")
 
@@ -287,14 +292,18 @@ session_id = await client.get_foreground_session_id()
 # Request TUI to display a specific session (TUI+server mode only)
 await client.set_foreground_session_id("session-123")
 
+
 # Subscribe to all lifecycle events
 def on_lifecycle(event):
     print(f"{event.type}: {event.session_id}")
 
+
 unsubscribe = client.on_lifecycle(on_lifecycle)
 
 # Subscribe to specific event type
-unsubscribe = client.on_lifecycle("session.foreground", lambda e: print(f"Foreground: {e.session_id}"))
+unsubscribe = client.on_lifecycle(
+    "session.foreground", lambda e: print(f"Foreground: {e.session_id}")
+)
 
 # Later, to stop receiving events:
 unsubscribe()
@@ -316,14 +325,17 @@ Define tools with automatic JSON schema generation using the `@define_tool` deco
 from pydantic import BaseModel, Field
 from copilot import CopilotClient, define_tool
 
+
 class LookupIssueParams(BaseModel):
     id: str = Field(description="Issue identifier")
 
+
 @define_tool(description="Fetch issue details from our tracker")
 async def lookup_issue(params: LookupIssueParams) -> str:
     issue = await fetch_issue(params.id)
     return issue.summary
 
+
 async with await client.create_session(
     on_permission_request=PermissionHandler.approve_all,
     model="gpt-5",
@@ -343,6 +355,7 @@ from copilot import CopilotClient
 from copilot.tools import Tool, ToolInvocation, ToolResult
 from copilot.session import PermissionHandler
 
+
 async def lookup_issue(invocation: ToolInvocation) -> ToolResult:
     issue_id = invocation.arguments["id"]
     issue = await fetch_issue(issue_id)
@@ -352,6 +365,7 @@ async def lookup_issue(invocation: ToolInvocation) -> ToolResult:
         session_log=f"Fetched issue {issue_id}",
     )
 
+
 async with await client.create_session(
     on_permission_request=PermissionHandler.approve_all,
     model="gpt-5",
@@ -471,6 +485,7 @@ from copilot.session_events import (
 )
 from copilot.session import PermissionHandler
 
+
 async def main():
     async with CopilotClient() as client:
         async with await client.create_session(
@@ -507,6 +522,7 @@ async def main():
             await session.send("Tell me a short story")
             await done.wait()  # Wait for streaming to complete
 
+
 asyncio.run(main())
 ```
 
@@ -678,7 +694,10 @@ async with await client.create_session(
     system_message={
         "mode": "customize",
         "sections": {
-            "tone": {"action": "replace", "content": "Respond in a warm, professional tone. Be thorough in explanations."},
+            "tone": {
+                "action": "replace",
+                "content": "Respond in a warm, professional tone. Be thorough in explanations.",
+            },
             "code_change_rules": {"action": "remove"},
             "guidelines": {"action": "append", "content": "\n* Always cite data sources"},
         },
@@ -698,6 +717,7 @@ You can also pass a transform callback as the `action` instead of a string. The
 def redact_paths(content: str) -> str:
     return content.replace("/home/user", "/***")
 
+
 async with await client.create_session(
     on_permission_request=PermissionHandler.approve_all,
     model="gpt-5",
@@ -785,9 +805,7 @@ from copilot.rpc import (
 from copilot.session_events import PermissionRequestShell
 
 
-def on_permission_request(
-    request: PermissionRequest, invocation: dict
-) -> PermissionRequestResult:
+def on_permission_request(request: PermissionRequest, invocation: dict) -> PermissionRequestResult:
     # ``PermissionRequest`` is a discriminated union — pattern-match on
     # the variant class to access the per-kind fields.
     match request:
@@ -871,6 +889,7 @@ async def handle_user_input(request, invocation):
         "wasFreeform": True,  # Whether the answer was freeform (not from choices)
     }
 
+
 async with await client.create_session(
     on_permission_request=PermissionHandler.approve_all,
     model="gpt-5",
@@ -893,12 +912,14 @@ async def on_pre_tool_use(input, invocation):
         "additionalContext": "Extra context for the model",
     }
 
+
 async def on_post_tool_use(input, invocation):
     print(f"Tool {input['toolName']} completed")
     return {
         "additionalContext": "Post-execution notes",
     }
 
+
 async def on_post_tool_use_failure(input, invocation):
     # Fires when a tool's result was a failure. `on_post_tool_use` only fires
     # on success, so register this handler to observe failed tool calls. The
@@ -908,27 +929,32 @@ async def on_post_tool_use_failure(input, invocation):
         "additionalContext": f"Retry guidance for {input['toolName']}",
     }
 
+
 async def on_user_prompt_submitted(input, invocation):
     print(f"User prompt: {input['prompt']}")
     return {
         "modifiedPrompt": input["prompt"],  # Optionally modify the prompt
     }
 
+
 async def on_session_start(input, invocation):
     print(f"Session started from: {input['source']}")  # "startup", "resume", "new"
     return {
         "additionalContext": "Session initialization context",
     }
 
+
 async def on_session_end(input, invocation):
     print(f"Session ended: {input['reason']}")
 
+
 async def on_error_occurred(input, invocation):
     print(f"Error in {input['errorContext']}: {input['error']}")
     return {
         "errorHandling": "retry",  # "retry", "skip", or "abort"
     }
 
+
 async with await client.create_session(
     on_permission_request=PermissionHandler.approve_all,
     model="gpt-5",
@@ -962,6 +988,7 @@ Register slash commands that users can invoke from the CLI TUI. When the user ty
 ```python
 from copilot.session import CommandDefinition, CommandContext, PermissionHandler
 
+
 async def handle_deploy(ctx: CommandContext) -> None:
     print(f"Deploying with args: {ctx.args}")
     # ctx.session_id  — the session where the command was invoked
@@ -969,6 +996,7 @@ async def handle_deploy(ctx: CommandContext) -> None:
     # ctx.command_name — command name without leading / (e.g. "deploy")
     # ctx.args         — raw argument string (e.g. "production")
 
+
 async with await client.create_session(
     on_permission_request=PermissionHandler.approve_all,
     commands=[
@@ -1030,11 +1058,14 @@ Shows a text input dialog with optional constraints:
 name = await session.ui.input("Enter your name:")
 
 # With options
-email = await session.ui.input("Enter email:", {
-    "title": "Email Address",
-    "description": "We'll use this for notifications",
-    "format": "email",
-})
+email = await session.ui.input(
+    "Enter email:",
+    {
+        "title": "Email Address",
+        "description": "We'll use this for notifications",
+        "format": "email",
+    },
+)
 ```
 
 ### Custom Elicitation
@@ -1042,17 +1073,19 @@ email = await session.ui.input("Enter email:", {
 For full control, use the `elicitation()` method with a custom JSON schema:
 
 ```python
-result = await session.ui.elicitation({
-    "message": "Configure deployment",
-    "requestedSchema": {
-        "type": "object",
-        "properties": {
-            "region": {"type": "string", "enum": ["us-east-1", "eu-west-1"]},
-            "replicas": {"type": "number", "minimum": 1, "maximum": 10},
+result = await session.ui.elicitation(
+    {
+        "message": "Configure deployment",
+        "requestedSchema": {
+            "type": "object",
+            "properties": {
+                "region": {"type": "string", "enum": ["us-east-1", "eu-west-1"]},
+                "replicas": {"type": "number", "minimum": 1, "maximum": 10},
+            },
+            "required": ["region"],
         },
-        "required": ["region"],
-    },
-})
+    }
+)
 
 if result["action"] == "accept":
     region = result["content"]["region"]
@@ -1066,6 +1099,7 @@ When the server (or an MCP tool) needs to ask the end-user a question, it sends
 ```python
 from copilot.session import ElicitationContext, ElicitationResult, PermissionHandler
 
+
 async def handle_elicitation(
     context: ElicitationContext,
 ) -> ElicitationResult:
@@ -1082,6 +1116,7 @@ async def handle_elicitation(
         "content": {"answer": "yes"},
     }
 
+
 async with await client.create_session(
     on_permission_request=PermissionHandler.approve_all,
     on_elicitation_request=handle_elicitation,
diff --git a/python/pyproject.toml b/python/pyproject.toml
index 43c18658d..a867fe51d 100644
--- a/python/pyproject.toml
+++ b/python/pyproject.toml
@@ -41,7 +41,7 @@ telemetry = [
 
 [dependency-groups]
 dev = [
-    "ruff>=0.1.0",
+    "ruff==0.16.0",
     "ty>=0.0.2,<0.0.25",
     "pytest>=7.0.0",
     "pytest-asyncio>=0.21.0",