Upstream sync: port 23 new commits (2026-04-13)

[Copilot]

Ports 23 upstream commits from github/copilot-sdk (up to 16f0ba2) into the Java SDK. Minimum CLI version bumped to 1.0.22.

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Before the change?

• MCP server configs used untyped Map<String, Object> — no compile-time safety, no HTTP server support
• No enableConfigDiscovery option (auto-discovery of .mcp.json, skill dirs)
• No ModelCapabilitiesOverride — couldn't override vision/token limits per session
• No Session FS support — callers couldn't provide a custom filesystem backend for session-scoped I/O

After the change?

Typed MCP server configs — McpServerConfig base with two concrete subtypes:

var servers = Map.of(
    "local",  new McpStdioServerConfig().setCommand("node").setArgs(List.of("server.js")).setTools(List.of("*")),
    "remote", new McpHttpServerConfig().setUrl("https://example.com/mcp").setTools(List.of("*"))
);

enableConfigDiscovery on SessionConfig/ResumeSessionConfig — when true, runtime auto-discovers .mcp.json and skill directories from workingDirectory, merged with explicit values.

ModelCapabilitiesOverride — overrides vision/reasoning/token-limit capabilities per session or on model switch:

session.setModel("claude-sonnet-4.5", null, new ModelCapabilitiesOverride()
    .setSupports(new ModelCapabilitiesOverrideSupports().setVision(false))).get();

Session FS — custom filesystem backend for session-scoped file I/O:

var client = new CopilotClient(new CopilotClientOptions()
    .setSessionFs(new SessionFsConfig()
        .setInitialCwd("/workspace")
        .setSessionStatePath(".sessions")
        .setConventions(SessionFsConventions.POSIX)));

var session = client.createSession(new SessionConfig()
    .setOnPermissionRequest(PermissionHandler.APPROVE_ALL)
    .setCreateSessionFsHandler(s -> new MySessionFsHandler(s.getSessionId()))).get();

SessionFsHandler interface covers 13 file operations: readFile, writeFile, appendFile, exists, stat, mkdir, readdir, readdirWithTypes, rm, rename, cp, copyDir, glob.

.lastmerge updated to 16f0ba278ebb25e2cd6326f932d60517ea926431.

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• mvn spotless:apply has been run to format the code
• mvn clean verify passes locally

Does this introduce a breaking change?

• Yes
• No

getMcpServers()/setMcpServers() on SessionConfig, ResumeSessionConfig, CustomAgentConfig and the wire request types changed from Map<String, Object> to Map<String, McpServerConfig>. Callers using raw maps must migrate to McpStdioServerConfig or McpHttpServerConfig.

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