feat: upgrade to rmcp 0.12.0 and sacp 10.0.0 by removing SSE transport #6304

codefromthecrypt · 2025-12-30T22:17:27Z

Summary

Upgrade to rmcp 0.12.0 and sacp 10.0.0 by removing SSE transport (dropped in rmcp 0.11.0).

The rmcp upgrade has the following impact:

SSE Transport Removed - Breaking change, use streamable HTTP instead. SSE removed from MCP spec due to sticky session requirements and load balancer incompatibility.
Custom Requests - Send arbitrary request methods beyond MCP spec and await responses. Codex sends codex/sandbox-state/update to set sandbox policy before tool execution, awaiting ack to guarantee ordering.
Custom Notifications - Bidirectional fire-and-forget messages for arbitrary methods. mcp-use sends custom/heartbeat and custom/broadcast to push server events to clients.
Streamable HTTP Graceful Shutdown - Server now terminates cleanly when clients are connected. Previously desktop apps couldn't quit because open MCP connections blocked shutdown.
More features soon - Task support for long-running operations with progress tracking, and improved elicitation enums with single/multi select and titles.

SSE Migration

SSE extensions can be migrated to http streamable alternatives or worst case mcp-proxy

Migration (use mcp-proxy):

extensions:
  agent-fin:
    type: stdio
    cmd: uvx
    args: [mcp-proxy, --sse-url, https://agent-fin.biodnd.com/sse]

Type of Change

Feature
Refactor / Code quality

AI Assistance

This PR was created or reviewed with AI assistance

Testing

./target/release/goose configure → SSE visible, warning shown, can delete
./target/release/goose run → Warning printed, SSE fails to start
just run-ui → Yellow alert, SSE visible, can delete

Related Issues

Relates to Failes to add extension (MCP-Tableau) #6241 (SSE extension fails to add)
Relates to Remote extension: invalid SSE POST endpoint discovered #893 (SSE POST endpoint issues)
Continues Adopt RMCP #3578 (Adopt RMCP)

Screenshots/Demos (for UX changes)

All these tests show there is a warning and people can actually delete sse extensions without manual config

These used a valid sse server that at least allows anonymous tools/list

  extensions:
    test-sse:
      enabled: true
      type: sse
      name: test-sse
      uri: https://agent-fin.biodnd.com/sse
      description: "Test SSE extension"

CLI Session Run

$  ./target/release/goose session                                                                                                                                                       
Warning: 'test-sse': SSE is unsupported, migrate to streamable_http
starting session | provider: tetrate model: claude-opus-4-1
    session id: 20251231_12
    working directory: /Users/codefromthecrypt/oss/goose

goose is running! Enter your instructions, or try asking what goose can do.

Context: ○○○○○○○○○○ 0% (0/200000 tokens)

CLI Configure Toggle Extensions

$  ./target/release/goose configure                                                                                                                                                       

This will update your existing config files
  if you prefer, you can edit them directly at /Users/codefromthecrypt/.config/goose

┌   goose-configure 
│
◇  What would you like to configure?
│  Toggle Extensions 
│
Warning: 'test-sse': SSE is unsupported, migrate to streamable_http
◆  enable extensions: (use "space" to toggle and "enter" to submit)

CLI Configure Remove Extension

$ ./target/release/goose configure

This will update your existing config files
  if you prefer, you can edit them directly at /Users/codefromthecrypt/.config/goose

┌   goose-configure 
│
◇  What would you like to configure?
│  Remove Extension 
│
Warning: 'test-sse': SSE is unsupported, migrate to streamable_http
◆  Select extensions to remove (note: you can only remove disabled extensions - use "space" to toggle and "enter" to submit)
│  ◻ test-sse (<)
│  ◻ memory 
│  ◻ autovisualiser 
│  ◻ chatrecall 
│  ◻ todo 
│  ◻ tutorial 
│  ◻ GitHub 
│  ◻ skills 
│  ◻ kiwi 
│  ◻ code_execution 
└

UI warns but doesn't fail completely on SSE

UI Extensions Section

$ just run-ui

Navigate to Settings > Extensions

github-actions · 2025-12-30T22:21:53Z

PR Preview Action v1.6.3
🚀 View preview at https://block.github.io/goose/pr-preview/pr-6304/
Built to branch `gh-pages` at 2025-12-31 06:29 UTC. Preview will be ready when the GitHub Pages deployment is complete.

michaelneale · 2025-12-31T00:48:29Z

cc @alexhancock FYI

codefromthecrypt · 2025-12-31T03:04:31Z

I am reworking this and almost done.. to use toast notification on existing sse config so users can know and still be able to delete or change them without manual editing config files

Remove SSE transport (dropped in rmcp 0.11.0). SSE extensions show warnings and can be deleted, but will not start. Use streamable HTTP or mcp-proxy for migration. Signed-off-by: Adrian Cole <[email protected]>

codefromthecrypt · 2025-12-31T06:09:47Z

crates/goose-server/src/routes/config_management.rs

+    let warnings = goose::config::get_warnings();
+    Ok(Json(ExtensionResponse {
+        extensions,
+        warnings,


so the key here to allow the UI to respond with a warning in a compatible way is to add an extra field to the response. This is used later in the screenshots of the PR

codefromthecrypt · 2025-12-31T06:10:32Z

crates/goose/src/agents/extension.rs

-    /// Server-sent events client with a URI endpoint
+    /// SSE transport is no longer supported - kept only for config file compatibility
    #[serde(rename = "sse")]
    Sse {


this retains only the minimal fields to keep the UI working, so that errors can be displayed and it can actually delete sse extensions

codefromthecrypt · 2025-12-31T06:11:28Z

crates/goose/src/config/extensions.rs

        .collect()
 }
+
+pub fn get_warnings() -> Vec<String> {


I chose to not unit test this because it is more distracting in this case, and hopefully we can reap all sse code in a version or two including this

codefromthecrypt · 2025-12-31T06:12:16Z

crates/goose/Cargo.toml


 [dev-dependencies]
-sacp = "10.0.0-alpha.3"
+sacp = { workspace = true }


sacp now can be a top level dep as we can use a later version of rmcp compatibly

Copilot

Pull request overview

This PR upgrades to rmcp 0.12.0 and sacp 10.0.0 by removing the deprecated SSE transport, which was dropped from the MCP spec due to load balancer incompatibility. The upgrade brings custom requests/notifications support and improved graceful shutdown.

Key changes:

SSE transport removed from all codebases (Rust, TypeScript, docs)
SSE config kept for backward compatibility with warnings
Migration path provided via mcp-proxy for legacy SSE extensions
Updated to use new RMCP/SACP builder patterns

Reviewed changes

Copilot reviewed 67 out of 69 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
Cargo.toml	Upgraded rmcp to 0.12.0, sacp to 10.0.0
crates/goose/Cargo.toml	Removed SSE transport features
crates/goose/src/agents/extension.rs	Deprecated SSE variant, kept for compatibility
crates/goose/src/agents/extension_manager.rs	SSE returns error instead of attempting connection
crates/goose/src/config/extensions.rs	Added warning generation for SSE extensions
crates/goose-server/src/routes/config_management.rs	Added warnings field to API response
crates/goose-cli/src/cli.rs	Removed --with-remote-extension flag
crates/goose-cli/src/session/builder.rs	Removed remote_extensions handling
crates/goose-cli/src/commands/configure.rs	Removed SSE option from configure dialog
crates/goose-cli/src/commands/acp.rs	Updated to use new SACP builder patterns
crates/goose/tests/acp_integration_test.rs	Updated tests to use new API constructors
ui/desktop/src/utils/providerUtils.ts	SSE fails immediately with error message
ui/desktop/src/components/settings/extensions/utils.ts	Removed SSE form handling
ui/desktop/src/components/settings/extensions/ExtensionsSection.tsx	Added warning banner for SSE extensions
ui/desktop/src/components/ConfigContext.tsx	Added extensionWarnings state
ui/desktop/openapi.json	Updated SSE schema to compatibility-only mode
documentation/static/servers.json	Updated JetBrains/Pieces to use stdio/HTTP
documentation/docs/*/.md	Replaced SSE references with Streamable HTTP

Files not reviewed (1)

ui/desktop/package-lock.json: Language not supported

crates/goose/src/agents/extension.rs

documentation/docs/mcp/cloudflare-mcp.md

Signed-off-by: Adrian Cole <[email protected]>

baxen

Looks great! I tested locally and handling of old extensions worked on the CLI and UI. Tested normal usage as well just to be sure the new version of rmcp is not impacting anything - things working great

## Summary Update MCP extension documentation to remove SSE transport option and standardize on "Streamable HTTP" naming. ### Type of Change - [x] Documentation ### Testing Documentation only - no code changes. ### Related Issues Part of #6304 Signed-off-by: Adrian Cole <[email protected]>

#6319 Signed-off-by: Adrian Cole <[email protected]>

codefromthecrypt · 2026-01-01T22:54:35Z

split off the docs update to #6319 to decouple the merge, but still keep the changes ready when folks are in

Copilot

Pull request overview

Copilot reviewed 49 out of 51 changed files in this pull request and generated no new comments.

Files not reviewed (1)

ui/desktop/package-lock.json: Language not supported

## Summary Update MCP extension documentation to remove SSE transport option and standardize on "Streamable HTTP" naming. ### Type of Change - [x] Documentation ### Testing Documentation only - no code changes. ### Related Issues Part of #6304 Signed-off-by: Adrian Cole <[email protected]>

codefromthecrypt force-pushed the remove-sse-transport branch 5 times, most recently from beae3e2 to 30d16ca Compare December 31, 2025 05:48

feat: upgrade to rmcp 0.12.0 and sacp 10.0.0

1c4bc62

Remove SSE transport (dropped in rmcp 0.11.0). SSE extensions show warnings and can be deleted, but will not start. Use streamable HTTP or mcp-proxy for migration. Signed-off-by: Adrian Cole <[email protected]>

codefromthecrypt force-pushed the remove-sse-transport branch from 30d16ca to 1c4bc62 Compare December 31, 2025 06:07

codefromthecrypt commented Dec 31, 2025

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codefromthecrypt marked this pull request as ready for review December 31, 2025 06:16

Copilot AI review requested due to automatic review settings December 31, 2025 06:16

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copilot feedback

8407d33

Signed-off-by: Adrian Cole <[email protected]>

baxen approved these changes Jan 1, 2026

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codefromthecrypt mentioned this pull request Jan 1, 2026

docs: remove SSE transport and rename to Streamable HTTP #6319

Merged

1 task

Split docs change to another PR

f31665a

#6319 Signed-off-by: Adrian Cole <[email protected]>

Copilot AI review requested due to automatic review settings January 1, 2026 22:53

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codefromthecrypt merged commit 5a5312a into main Jan 1, 2026
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codefromthecrypt deleted the remove-sse-transport branch January 1, 2026 23:07

github-actions bot mentioned this pull request Jan 6, 2026

chore(release): release version 1.19.0 (minor) #6344

Merged

BrewTestBot mentioned this pull request Jan 6, 2026

block-goose-cli 1.19.0 Homebrew/homebrew-core#261531

Merged

feat: upgrade to rmcp 0.12.0 and sacp 10.0.0 by removing SSE transport #6304

feat: upgrade to rmcp 0.12.0 and sacp 10.0.0 by removing SSE transport #6304

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Summary

SSE Migration

Type of Change

AI Assistance

Testing

Related Issues

Screenshots/Demos (for UX changes)

CLI Session Run

CLI Configure Toggle Extensions

CLI Configure Remove Extension

UI warns but doesn't fail completely on SSE

UI Extensions Section

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github-actions bot commented Dec 30, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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codefromthecrypt commented Dec 30, 2025 •

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