[reference-impl-sync] Reference Implementation sync: 37 new commits (2026-05-27)

[github-actions]

Automated Reference Implementation Sync

There are 37 new commits in the official Copilot SDK since the last merge.

• Last merged commit: f4d22d70016c377881d86e4c77f8a3f93746ffae
• Reference Implementation HEAD: 60104052cd914949ddf8c7a31e1856cd6db0a57c

Recent reference implementation commits

60104052 Multitenancy hardening: Client Mode (#1428)
9017d85e Update `@github/copilot` to 1.0.55-5 (#1456)
b40a6f2d Move java to monorepo. Phase 05: Cross-Cutting Updates (#1441)
c5d9b82b Add extract-to-cache build mode for the Copilot CLI (#1450)
91d94103 Demote scenario-builds CI to manual-only (workflow_dispatch) (#1448)
08a5a20c Update `@github/copilot` to 1.0.55-4 (#1453)
8c83e15c Add MessageOptions.agentMode and fix per-message mode misuse (#1438)
ed8facbe Update `@github/copilot` to 1.0.55-1 (#1432)
3f0220b5 Fixes #1434 Repackaging. (#1437)
36d1906c Add post-tool-use failure hooks (#1421)
183cc441 Preserve JSON-RPC error data in .NET (#1425)
3dd7b017 SDK: Align canvas with codegen pipeline, add e2e tests (#1413)
ac6de48d Add cross-SDK RPC E2E coverage (#1424)
c69ea434 Change title from 'GitHub Copilot SDK documentation' to 'Copilot SDK' (#1386)
98ff3c26 Fix flaky SDK E2E tests (#1418)
89fd30c2 Update vulnerable npm lockfile dependencies (#1415)
8e67f645 C# codegen: add isOpaqueJson guard to resolveRpcType (#1414)
d6f58034 Bump brace-expansion (#1325)
afb51fc5 Update `@github/copilot` to 1.0.55-0 (#1412)
86a78c89 Update `@github/copilot` to 1.0.54 (#1411)

Instructions

You MUST follow these steps in order. Do NOT improvise or skip scripts.

1. ✅✅Read .github/prompts/agentic-merge-reference-impl.prompt.md in full before starting✅✅

❌❌Do NOT clone the reference implementation manually — the start script does this.❌❌
❌❌Do NOT update .lastmerge manually — the finish script does this.❌❌
❌❌Do NOT skip the finish script — it syncs codegen versions and updates .lastmerge.❌❌

Generated by Reference Implementation Sync · ● 2.3M · ◷

• expires on Jun 2, 2026, 6:49 PM UTC