Guard request dispatch so malformed calls error instead of hanging the client

Message

A tool call that fails during tool lookup or schema validation (before the inner handler guard) escaped uncaught and produced no JSON-RPC response, so a live stdio client hung forever waiting for a reply. Wrap the whole request branch of mcp-server-handle-message in a guard that returns make-error-response on any error. Bump 0.16.0 -> 0.16.1.

Changed

 package.sgl              |  2 +-
 src/sigil/mcp/server.sgl | 13 ++++++++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

Diff

package.sglmodified

@@ -7,7 +7,7 @@

7

8

(package

9

name: "sigil-mcp"

−10

version: "0.16.0"

+10

version: "0.16.1"

11

sigil: "^0.16"

12

description: "Library for building MCP servers in Sigil"

13

url: "https://codeberg.org/sigil/sigil-mcp"

src/sigil/mcp/server.sglmodified

@@ -361,6 +361,17 @@

361

(let ((method (jsonrpc-request-method msg))

362

(params (or (jsonrpc-request-params msg) '()))

363

(id (jsonrpc-request-id msg)))

+364

;; Guard the entire request dispatch so any error during tool

+365

;; lookup, schema validation, or handler execution still returns a

+366

;; JSON-RPC error response. Without this, an uncaught error escapes

+367

;; the read loop and a live client hangs forever waiting for a reply.

+368

(guard (e (else

+369

(let ((err-msg (guard (fe (else "unknown error"))

+370

(format-exception e))))

+371

(guard (le (else #f))

+372

(log-error "request dispatch failed" id: id error: err-msg))

+373

(make-error-response id error-internal

+374

(format "Internal error: ~a" err-msg)))))

375

(log-debug "request" method: method id: id)

376

(cond

377

((equal? method "initialize")

@@ -385,7 +396,7 @@

396

(else

397

(log-warn "Unknown method" method: method)

398

(make-error-response id error-method-not-found

−388

(format "Unknown method: ~a" method))))))

+399

(format "Unknown method: ~a" method)))))))

400

((jsonrpc-notification? msg)

401

;; Handle notifications (no response expected)

402

(let ((method (jsonrpc-notification-method msg)))