Fix @mention regex to ignore email addresses in prompts

Tighten context-pattern regex to require the first character after @
to be /, ~, or . so only valid path references are captured. Previously,
text like user@example.com would extract the domain as a context path,
causing a URISyntaxException.

Fixes #379

🤖 Generated with [eca](https://eca.dev)

Co-Authored-By: eca <git@eca.dev>

Author: ericdallo

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Fix MCP OAuth browser not opening on Windows by using `cmd /c start` instead of `java.awt.Desktop`, which is unavailable in the native image.
 - Improve server shutdown speed for remote MCP servers.
 - Extract git/gh instructions from `shell_command` into a dedicated `git` tool with a condensed prompt, reducing per-turn token overhead.
+- Fix crash when `@` signs in prompts (e.g. email addresses) are misinterpreted as context mentions. #379
 
 ## 0.117.1
 

src/eca/features/context.clj

@@ -126,7 +126,7 @@
    Parse lines if present in contexts like @/path/to/file:L1-L4"
   [prompt db]
   (let [ ;; Capture @<path> with optional :L<start>-L<end>
-        context-pattern #"@([^\s:]+)(?::L(\d+)-L(\d+))?"
+        context-pattern #"@([/~\.][^\s:]+)(?::L(\d+)-L(\d+))?"
         matches (re-seq context-pattern prompt)
         raw-contexts (mapv (fn [[_ path s e]]
                              (assoc-some {:type (if (fs/directory? path) "directory" "file")

test/eca/features/context_test.clj

@@ -343,6 +343,10 @@
     (is (match?
          nil
          (f.context/contexts-str-from-prompt "check /path/to/file" (h/db)))))
+  (testing "email address is not a context mention"
+    (is (match?
+         nil
+         (f.context/contexts-str-from-prompt "send email to user@example.com" (h/db)))))
   (testing "Context mention"
     (with-redefs [fs/readable? (constantly true)
                   llm-api/refine-file-context (constantly "Some content")]