feat: path budget - a file's path stays at 160 characters or fewer; new, rename, move and raw accept refuse more, lint reports Long Paths (#163)

Files changed:
- CHANGES.md
- README.md
- VERSION
- instructions/page-lifecycle.md
- kb/CONTRACT.md
- tools/CONTRACT.md
- tools/chemenu/commands/_util.py
- tools/chemenu/commands/lint.py
- tools/chemenu/commands/new_page.py
- tools/chemenu/commands/page_ops.py
- tools/chemenu/commands/raw_cmd.py
- tools/chemenu/lint_core.py
- tools/chemenu/tests/test_lint.py
- tools/chemenu/tests/test_new_page.py
- tools/chemenu/tests/test_page_ops.py
- tools/chemenu/tests/test_raw_cmd.py
- tools/chemenu/tests/test_titles.py
- tools/chemenu/titles.py

CHANGES.md

@@ -59,13 +59,14 @@ concern - readable here, never shipped as something to parse.
 
 ---
 
-## 8.0.0-beta.11 - 2026-09-30 - setup-instance step 15 names --no-push for a local-only first publish; gates.md and a docstring follow #159
+## 8.0.0-beta.12 - 2026-09-30 - Path budget: a file's path stays at 160 characters or fewer so a Windows checkout works without long paths (#163)
 
 **Author:** Torben Nehmer
 
 **Breaking Change:**
 - Page titles must form valid, unique file names on Windows and macOS: new and rename refuse forbidden characters, reserved names (including INDEX and COLLECTION), a trailing dot or space, and titles that collide with another page by case or Unicode normalization; lint reports existing violations as hard errors - rename each affected page with tools/wikitool rename
 - publish without --no-push now exits 1 before committing when the remote is unreachable or not configured, where it used to commit locally and fail at the push - an offline session or a local-only instance must pass --no-push
+- new, rename, move and raw accept refuse a target whose path below the instance root is over 160 characters (UTF-16 code units); lint reports existing files over it as Long Paths (advisory) - rename each affected page with tools/wikitool rename, and shorten an incoming/ file name before raw accept
 
 **Migration:** none required - No page format changes; the rule only refuses titles, and each affected page is renamed individually with tools/wikitool rename
 
@@ -85,6 +86,7 @@ concern - readable here, never shipped as something to parse.
 - Bug-report collector: tools/bugreport.py and instructions/bug-report.md
 - Bug-report collector can pseudonymise identities, in two stages
 - publish: the gate lists the staged state; a missing or unreachable remote stops before the commit
+- Path budget: a file's path stays at 160 characters or fewer so a Windows checkout works without long paths (#163)
 
 **Low impact**
 - version bump no longer points at version release in its output
@@ -120,6 +122,25 @@ concern - readable here, never shipped as something to parse.
 - setup-instance step 15 names --no-push for a local-only first publish; gates.md and a docstring follow #159
 <!-- /wikitool:bumps -->
 
+### Path budget: a file's path stays at 160 characters or fewer so a Windows checkout works without long paths (#163)
+
+Windows counts 259 characters for a whole path, the install folder included, and the target system
+has long paths off. A page title long enough to be a sentence made a checkout fail there, in a
+place nobody would look. The path of any file below the instance root now has a budget of 160
+characters, counted in UTF-16 code units the way Windows counts (an emoji takes two); the folder
+limit that `doctor` and the install preflight enforce is the other half of the same sum.
+
+`new` (every root), `rename` (`--to` only, also under `--dry-run`), `move` (a single page, and
+`--reconcile`, which skips and names the target as it does for an occupied one) and `raw accept`
+(the remedy is renaming the file in `incoming/`; `incoming/` and `raw/` stay unchanged) refuse a
+longer path with exit 1 before writing anything. `lint` reports existing files over the budget
+under a new advisory finding, Long Paths, for `kb/` and `raw/`; it is not a hard error, so
+`--fail-on-error` does not start failing a corpus that predates the rule. The fix for an existing
+page is `wikitool rename`, and `--from` is never checked, so renaming away from a long title works.
+
+The measurement is `titles.path_budget_problem`, a pure function beside the title rules, and
+`kb/CONTRACT.md` § Titles are identifiers carries the normative statement.
+
 ### setup-instance step 15 names --no-push for a local-only first publish; gates.md and a docstring follow #159
 
 The close-out review of #159 found three places the change had not reached. `setup-instance.md`