fix(claude): stop reformatting all of ~/.claude.json on every apply

AGENTS.md

@@ -45,6 +45,8 @@ Never assume you are on `main` or in the primary checkout directory.
   [configuration]
   # /path/to/script.tmpl:END:section:12345678
   ```
+- **Default new `modify_` scripts to a pure `chezmoi:modify-template`** (`{{- /* chezmoi:modify-template */ -}}` as the first line, e.g. `dot_codex/modify_config.toml`, `dot_claude/modify_settings.json`) rather than embedding another language (Python, shell) inside a rendered template string. Requires the source filename to have **no `.tmpl` suffix** and **no executable bit** — both confirmed empirically to break chezmoi's dispatch (it silently falls through to the legacy executable-script code path instead, and `.chezmoi.stdin` never gets populated). Parse the incoming file with `fromJson`/`fromToml`/`fromYaml` on `.chezmoi.stdin` (guard with `{{- if .chezmoi.stdin -}}` for a not-yet-existing target), transform with `mergeOverwrite`/`setValueAtPath`/`omit`, serialize back with `toPrettyJson`/`toToml`/`toYaml`. `toPrettyJson`'s return value always carries a trailing `\n` that `-}}` trim markers can't remove (trim only strips surrounding template *text*, not a pipeline's runtime value) — pipe through `trimSuffix "\n"` if the target shouldn't end in a blank line.
+  **Known exception, don't relitigate:** `modify_dot_claude.json.tmpl` stays Python. Go's `fromJson`/`toPrettyJson` always alphabetize map keys (`encoding/json` marshal behavior, no workaround via these functions) — fine for a script that owns its whole output, but that script's entire point is touching one key in a ~2000-line file Claude Code itself constantly rewrites with its own key order and literal UTF-8; a Go-template rewrite would reformat the whole file every apply. Reconsider only if chezmoi ever exposes an order-preserving JSON codec.
 
 ## Chezmoi externals & scripts
 

src/chezmoi/modify_dot_claude.json.tmpl

@@ -4,7 +4,16 @@
 # (startup counts, seen-tips history, feature flags, etc.). We only inject our
 # managed preferences and leave everything else untouched.
 # Deployment config (permissions, env, sandbox) lives in ~/.claude/settings.json;
-# see dot_claude/modify_settings.json.tmpl.
+# see dot_claude/modify_settings.json.
+#
+# Deliberately NOT a chezmoi:modify-template (see src/chezmoi/AGENTS.md for
+# the default convention). fromJson/toPrettyJson always alphabetize keys
+# (Go's encoding/json map behavior, no way around it with those functions) --
+# fine for the two settings.json scripts, which already chose to fully own
+# their output, but this file's whole point is to touch nothing but one key
+# in a ~2000-line file Claude Code itself constantly rewrites with its own
+# key order and literal UTF-8. A Go-template rewrite would reformat that
+# entire file on every apply, exactly the diff-noise bug this script fixes.
 import json
 import sys
 
@@ -27,4 +36,9 @@ def deep_merge(d1, d2):
 
 merged = deep_merge(existing.copy(), preferences)
 
-print(json.dumps(merged, indent=2, sort_keys=True), end="")
+# No sort_keys, no default ensure_ascii: Claude Code writes this file with
+# its own key order and literal UTF-8. Matching that means an apply that
+# only touches editorMode produces a single-line diff instead of
+# reformatting the whole ~2000-line file (key resort + unicode escaping)
+# every time, which made real changes impossible to spot in the noise.
+print(json.dumps(merged, indent=2, ensure_ascii=False), end="")