fix(500): the hooks decode a \u escape to UTF-8 in any locale and any awk

scribe_json_unescape wrote each escaped code point with sprintf("%c", n),
which writes the character only under gawk in a UTF-8 locale; gawk in the C
locale and mawk in any locale write the single byte n % 256. The server
escapes every non-ASCII character, so "·" reached the session as 0xB7, "—"
as 0x14 and an emoji as a NUL wherever a hook ran without a UTF-8 locale.
The decoder now encodes UTF-8 itself under LC_ALL=C. A new test sends what
the server sends from a bare environment, in three locales (#5495).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

plugin/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "scribe",
   "description": "Scribe for Claude Code: connects the scribe MCP server, adds the hooks that deliver live project state and relevant records at the right moment, ships the shared client-neutral Scribe skills (using-scribe, writing-plans, reporting-back, systematic-debugging, verification, brainstorming, reusing-code, shape-accounting, family-canon), and syncs your saved Scribe Processes as skills (/scribe:sync).",
-  "version": "2026.10.09.1845",
+  "version": "2026.10.09.1850",
   "author": {
     "name": "Bryan Van Deusen"
   },

plugin/hooks/scribe_defs.sh

@@ -205,8 +205,26 @@ scribe_json_len() {
 }
 
 # Raw JSON string bodies on stdin → text. One line in, one value out.
+#
+# A `\uXXXX` ESCAPE IS ENCODED AS UTF-8 HERE, BYTE BY BYTE, UNDER LC_ALL=C.
+# The server escapes every non-ASCII character this way (the JSON default),
+# and `sprintf("%c", n)` for n > 127 means a different thing in every awk and
+# locale: gawk in a UTF-8 locale writes the character, gawk in the C locale
+# and mawk write the single byte n % 256. So "·" (U+00B7) arrived as a lone
+# 0xB7 and "—" (U+2014) as 0x14 wherever the hook ran without a UTF-8 locale —
+# found by a test that ran the hook with a bare environment (milestone 500).
+# Under LC_ALL=C every awk writes exactly the byte asked for, so the encoding
+# below is the only one that happens.
 scribe_json_unescape() {
-  awk '
+  LC_ALL=C awk '
+    function utf8(n) {
+      if (n < 128) return sprintf("%c", n)
+      if (n < 2048) return sprintf("%c%c", 192 + int(n / 64), 128 + n % 64)
+      if (n < 65536) return sprintf("%c%c%c", 224 + int(n / 4096),
+                                    128 + int(n / 64) % 64, 128 + n % 64)
+      return sprintf("%c%c%c%c", 240 + int(n / 262144), 128 + int(n / 4096) % 64,
+                     128 + int(n / 64) % 64, 128 + n % 64)
+    }
     function hex4(h,   i, c, d, v) {
       v = 0
       for (i = 1; i <= 4; i++) {
@@ -246,7 +264,7 @@ scribe_json_unescape() {
               i += 6
             }
           }
-          o = o sprintf("%c", hi)
+          o = o utf8(hi)
         }
         else o = o d
       }