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Fix built-in MCP startup failures and remove deprecated Puppeteer server #28

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Merged
enowdev merged 1 commit into from
Aug 13, 2026
+213 −48
Merged

Fix built-in MCP startup failures and remove deprecated Puppeteer server #28

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52 changes: 21 additions & 31 deletions internal/hub/catalog/mcp.json
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@
"homepage": "https://github.com/modelcontextprotocol/servers/tree/main/src/filesystem",
"author": "Model Context Protocol",
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-filesystem", "${HOME}"],
"args": ["-y", "@modelcontextprotocol/server-filesystem@2026.7.10", "${HOME}"],
"setup": "Edit the last argument to the directory you want exposed. Node is required."
},
{
Expand All @@ -18,8 +18,8 @@
"homepage": "https://github.com/modelcontextprotocol/servers/tree/main/src/fetch",
"author": "Model Context Protocol",
"command": "uvx",
"args": ["mcp-server-fetch"],
"setup": "Needs uv (https://docs.astral.sh/uv/)."
"args": ["--from", "mcp-server-fetch==2026.7.10", "--with", "mcp==1.9.4", "mcp-server-fetch"],
"setup": "Needs uv (https://docs.astral.sh/uv/). Versions are pinned because newer MCP SDK releases break this server."
},
{
"id": "git",
Expand All @@ -29,8 +29,8 @@
"homepage": "https://github.com/modelcontextprotocol/servers/tree/main/src/git",
"author": "Model Context Protocol",
"command": "uvx",
"args": ["mcp-server-git", "--repository", "."],
"setup": "Point --repository at the checkout you want. Needs uv."
"args": ["--from", "mcp-server-git==2026.7.10", "--with", "mcp==1.9.4", "mcp-server-git", "--repository", "."],
"setup": "Point --repository at the checkout you want. Needs uv. Versions are pinned because newer MCP SDK releases break this server."
},
{
"id": "github",
Expand All @@ -53,7 +53,7 @@
"homepage": "https://github.com/modelcontextprotocol/servers/tree/main/src/postgres",
"author": "Model Context Protocol",
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-postgres", "postgresql://localhost/mydb"],
"args": ["-y", "@modelcontextprotocol/server-postgres@0.6.2", "postgresql://localhost/mydb"],
"setup": "Replace the connection string with your own."
},
{
Expand All @@ -64,8 +64,8 @@
"homepage": "https://github.com/modelcontextprotocol/servers/tree/main/src/sqlite",
"author": "Model Context Protocol",
"command": "uvx",
"args": ["mcp-server-sqlite", "--db-path", "./data.db"],
"setup": "Point --db-path at your database. Needs uv."
"args": ["--from", "mcp-server-sqlite==2025.4.25", "--with", "mcp==1.9.4", "mcp-server-sqlite", "--db-path", "./data.db"],
"setup": "Point --db-path at your database. Needs uv. Versions are pinned because newer MCP SDK releases break this server."
},
{
"id": "memory",
Expand All @@ -75,7 +75,7 @@
"homepage": "https://github.com/modelcontextprotocol/servers/tree/main/src/memory",
"author": "Model Context Protocol",
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-memory"]
"args": ["-y", "@modelcontextprotocol/server-memory@2026.7.4"]
},
{
"id": "sequential-thinking",
Expand All @@ -85,7 +85,7 @@
"homepage": "https://github.com/modelcontextprotocol/servers/tree/main/src/sequentialthinking",
"author": "Model Context Protocol",
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-sequential-thinking"]
"args": ["-y", "@modelcontextprotocol/server-sequential-thinking@2026.7.4"]
},
{
"id": "time",
Expand All @@ -95,8 +95,8 @@
"homepage": "https://github.com/modelcontextprotocol/servers/tree/main/src/time",
"author": "Model Context Protocol",
"command": "uvx",
"args": ["mcp-server-time"],
"setup": "Needs uv."
"args": ["--from", "mcp-server-time==2026.7.10", "--with", "mcp==1.23.0", "mcp-server-time"],
"setup": "Needs uv. Versions are pinned because newer MCP SDK releases break older server packages."
},
{
"id": "slack",
Expand All @@ -106,7 +106,7 @@
"homepage": "https://github.com/modelcontextprotocol/servers/tree/main/src/slack",
"author": "Model Context Protocol",
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-slack"],
"args": ["-y", "@modelcontextprotocol/server-slack@2025.4.25"],
"env": { "SLACK_BOT_TOKEN": "", "SLACK_TEAM_ID": "" },
"needs_keys": ["SLACK_BOT_TOKEN", "SLACK_TEAM_ID"],
"setup": "Create a Slack app, add bot scopes, and install it to the workspace."
Expand All @@ -119,21 +119,11 @@
"homepage": "https://github.com/modelcontextprotocol/servers/tree/main/src/brave-search",
"author": "Model Context Protocol",
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-brave-search"],
"args": ["-y", "@modelcontextprotocol/server-brave-search@0.6.2"],
"env": { "BRAVE_API_KEY": "" },
"needs_keys": ["BRAVE_API_KEY"],
"setup": "Free tier keys at https://brave.com/search/api/."
},
{
"id": "puppeteer",
"name": "Puppeteer",
"summary": "Browser automation through Puppeteer. Antares has its own browser tool; use this when you want the Puppeteer API instead.",
"tags": ["browser", "web"],
"homepage": "https://github.com/modelcontextprotocol/servers/tree/main/src/puppeteer",
"author": "Model Context Protocol",
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-puppeteer"]
},
{
"id": "notion",
"name": "Notion",
Expand All @@ -142,7 +132,7 @@
"homepage": "https://github.com/makenotion/notion-mcp-server",
"author": "Notion",
"command": "npx",
"args": ["-y", "@notionhq/notion-mcp-server"],
"args": ["-y", "@notionhq/notion-mcp-server@2.5.1"],
"env": { "NOTION_TOKEN": "" },
"needs_keys": ["NOTION_TOKEN"],
"setup": "Create an internal integration at https://www.notion.so/my-integrations and share the pages with it."
Expand All @@ -154,8 +144,8 @@
"tags": ["issues", "productivity"],
"homepage": "https://linear.app/docs/mcp",
"author": "Linear",
"url": "https://mcp.linear.app/sse",
"setup": "A hosted server — it will ask you to authorise on first use."
"url": "https://mcp.linear.app/mcp",
"setup": "Hosted Streamable HTTP server. OAuth is required; bearer-token headers can be configured manually."
},
{
"id": "sentry",
Expand All @@ -164,8 +154,8 @@
"tags": ["observability"],
"homepage": "https://docs.sentry.io/product/sentry-mcp/",
"author": "Sentry",
"url": "https://mcp.sentry.dev/sse",
"setup": "A hosted server — it will ask you to authorise on first use."
"url": "https://mcp.sentry.dev/mcp",
"setup": "Hosted Streamable HTTP server. OAuth is required; bearer-token headers can be configured manually."
},
{
"id": "playwright",
Expand All @@ -175,7 +165,7 @@
"homepage": "https://github.com/microsoft/playwright-mcp",
"author": "Microsoft",
"command": "npx",
"args": ["-y", "@playwright/mcp@latest"]
"args": ["-y", "@playwright/mcp@0.0.79"]
},
{
"id": "everything",
Expand All @@ -185,6 +175,6 @@
"homepage": "https://github.com/modelcontextprotocol/servers/tree/main/src/everything",
"author": "Model Context Protocol",
"command": "npx",
"args": ["-y", "@modelcontextprotocol/server-everything"]
"args": ["-y", "@modelcontextprotocol/server-everything@2026.7.4"]
}
]
116 changes: 99 additions & 17 deletions internal/mcp/client.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,12 +7,14 @@ import (
"bytes"
"context"
"encoding/json"
"errors"
"fmt"
"io"
"log/slog"
"net/http"
"os"
"os/exec"
"path/filepath"
"strings"
"sync"
"time"
Expand Down Expand Up @@ -55,10 +57,11 @@ type rpcRequest struct {

// rpcResponse is a JSON-RPC 2.0 response.
type rpcResponse struct {
JSONRPC string `json:"jsonrpc"`
ID *int64 `json:"id"`
Result json.RawMessage `json:"result"`
Error *rpcError `json:"error"`
JSONRPC string `json:"jsonrpc"`
ID *int64 `json:"id"`
Result json.RawMessage `json:"result"`
Error *rpcError `json:"error"`
transportErr error
}

type rpcError struct {
Expand Down Expand Up @@ -386,7 +389,34 @@ type stdioTransport struct {
// otherwise make every future call wait the full timeout forever. After
// maxConsecutiveTimeouts the transport self-closes so the next caller fails
// fast and the process is reaped. Any successful reply resets it to zero.
timeouts int
timeouts int
stderr stderrCapture
stderrDone chan struct{}
readerErr error
}

type stderrCapture struct {
mu sync.Mutex
buf []byte
}

const maxStderrBytes = 16 << 10

func (c *stderrCapture) append(line string) {
c.mu.Lock()
defer c.mu.Unlock()
c.buf = append(c.buf, line...)
c.buf = append(c.buf, '\n')
if len(c.buf) > maxStderrBytes {
copy(c.buf, c.buf[len(c.buf)-maxStderrBytes:])
c.buf = c.buf[:maxStderrBytes]
}
}

func (c *stderrCapture) String() string {
c.mu.Lock()
defer c.mu.Unlock()
return strings.TrimSpace(string(c.buf))
}

// maxConsecutiveTimeouts is how many back-to-back ctx.Done timeouts a stdio
Expand All @@ -397,7 +427,7 @@ func newStdioTransport(cfg ServerConfig) (transport, error) {
if strings.TrimSpace(cfg.Command) == "" {
return nil, fmt.Errorf("stdio transport needs a command")
}
cmd := exec.Command(cfg.Command, cfg.Args...)
cmd := exec.Command(cfg.Command, expandArgs(cfg.Args)...)
cmd.Env = os.Environ()
for k, v := range cfg.Env {
cmd.Env = append(cmd.Env, k+"="+v)
Expand All @@ -419,26 +449,48 @@ func newStdioTransport(cfg ServerConfig) (transport, error) {
if err := cmd.Start(); err != nil {
return nil, fmt.Errorf("start %s: %w", cfg.Command, err)
}
go func() {
sc := bufio.NewScanner(stderr)
for sc.Scan() {
slog.Debug("mcp server stderr", "command", cfg.Command, "line", sc.Text())
}
}()

t := &stdioTransport{
cmd: cmd,
stdin: stdin,
stdout: bufio.NewReaderSize(stdout, 1<<20),
pending: map[int64]chan *rpcResponse{},
readerDone: make(chan struct{}),
stderrDone: make(chan struct{}),
}
go func() {
defer close(t.stderrDone)
sc := bufio.NewScanner(stderr)
for sc.Scan() {
t.stderr.append(sc.Text())
slog.Debug("mcp server stderr", "command", cfg.Command, "line", sc.Text())
}
}()
// Reap the child if it exits on its own so it never sits as a zombie until
// the next Close/Refresh. Wait is idempotent via waitOnce.
go func() { _ = t.reap() }()
return t, nil
}

func expandArgs(args []string) []string {
home, _ := os.UserHomeDir()
out := make([]string, len(args))
for i, arg := range args {
arg = os.Expand(arg, func(key string) string {
if key == "HOME" && os.Getenv(key) == "" {
return home
}
return os.Getenv(key)
})
if arg == "~" {
arg = home
} else if strings.HasPrefix(arg, "~/") || strings.HasPrefix(arg, `~\`) {
arg = filepath.Join(home, arg[2:])
}
out[i] = arg
}
return out
}

func (t *stdioTransport) reap() error {
t.waitOnce.Do(func() {
if t.cmd != nil {
Expand Down Expand Up @@ -496,21 +548,41 @@ func (t *stdioTransport) startReader() {
}

// failPending delivers an error to every waiting caller and clears the map.
func (t *stdioTransport) failPending(err error) {
func (t *stdioTransport) failPending(readErr error) {
err := t.processError(readErr)
t.pendingMu.Lock()
t.readerErr = err
for id, ch := range t.pending {
// Non-blocking: the caller may have already returned on ctx.Done and
// stopped reading. The channel is buffered(1), so a live caller still
// receives this; an abandoned one must not wedge the reader goroutine.
select {
case ch <- &rpcResponse{Error: &rpcError{Message: err.Error()}}:
case ch <- &rpcResponse{transportErr: err}:
default:
}
delete(t.pending, id)
}
t.pendingMu.Unlock()
}

func (t *stdioTransport) processError(readErr error) error {
waitErr := t.reap()
<-t.stderrDone
stderr := t.stderr.String()
switch {
case waitErr != nil && stderr != "":
return fmt.Errorf("MCP server exited (%v): %s", waitErr, stderr)
case waitErr != nil:
return fmt.Errorf("MCP server exited: %w", waitErr)
case stderr != "":
return fmt.Errorf("MCP server closed stdout: %s", stderr)
case readErr != nil && !errors.Is(readErr, io.EOF):
return fmt.Errorf("MCP server output failed: %w", readErr)
default:
return errors.New("MCP server exited before replying")
}
}

func (t *stdioTransport) send(ctx context.Context, req rpcRequest) (*rpcResponse, error) {
// One in-flight request at a time — required for line-delimited stdio.
t.sendMu.Lock()
Expand Down Expand Up @@ -563,9 +635,19 @@ func (t *stdioTransport) send(ctx context.Context, req rpcRequest) (*rpcResponse
}
return nil, ctx.Err()
case <-t.readerDone:
// The background reader exited (EOF, child died). Surface the failure.
return nil, fmt.Errorf("mcp connection lost")
// The background reader exited (EOF, child died). Surface its exit status
// and bounded stderr tail instead of reducing every startup crash to EOF.
t.pendingMu.Lock()
err := t.readerErr
t.pendingMu.Unlock()
if err == nil {
err = errors.New("MCP server connection lost")
}
return nil, err
case r := <-ch:
if r.transportErr != nil {
return nil, r.transportErr
}
t.pendingMu.Lock()
t.timeouts = 0
t.pendingMu.Unlock()
Expand Down
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