fix(date): cap strftime widths and account padding in memoryLimit (#895)

* fix(date): cap strftime widths and account padding in memoryLimit

- Clamp numeric strftime pad widths to MAX_STRFTIME_PAD (1024)
- Export estimateStrftimePaddingMemory for the date filter to charge memoryLimit
- Replace unbounded pad() concatenation loop with ch.repeat + single concat
- Add regression tests for clamping and memoryLimit on huge %width directives

Co-authored-by: Cursor <[email protected]>

* fix(date): harden strftime memory accounting and document security model

Move strftime memory charging into the same formatting path used for padding, enforce pre-allocation checks, and add regression tests for non-string date format PoCs. Add dedicated docs clarifying that memoryLimit is cooperative DoS mitigation and not strict heap isolation.

Co-authored-by: Cursor <[email protected]>

* docs(zh-cn): add security model docs for DoS limits

Add a Chinese security-model tutorial and link it from the Chinese DoS guide to clarify that memoryLimit is cooperative accounting, list uncounted custom conversion cases, and recommend avoiding fully user-defined templates in online services.

Co-authored-by: Cursor <[email protected]>

* docs: consolidate DoS docs into security-model pages

Merge DoS guidance into security-model docs in both English and Chinese, and remove the placeholder dos.md pages to avoid duplicate/redirect-only docs.

Co-authored-by: Cursor <[email protected]>

* docs: merge DoS details into security-model docs

Move the detailed parseLimit/renderLimit/memoryLimit explanations and examples into the English and Chinese security-model pages so content from the removed dos pages is preserved.

Co-authored-by: Cursor <[email protected]>

* docs: reorganize security-model structure for clarity

Restructure English and Chinese security-model docs into a consistent flow: security boundary, limits overview, per-limit details, and online service guidance.

Co-authored-by: Cursor <[email protected]>

* refactor(strftime): simplify %N width parsing logic

Use regex-backed width assumptions to simplify %N width normalization and padding memory accounting while keeping behavior equivalent.

Co-authored-by: Cursor <[email protected]>

* refactor(strftime): rely on memoryLimit for width control

Remove MAX_STRFTIME_PAD hard capping and rely on memoryLimit enforcement before padding allocation. Update strftime/date tests and security-model docs to match the new boundary and renderLimit caveats.

Co-authored-by: Cursor <[email protected]>

* fix(strftime): use add() once for padding, minimize churn

- pad(): replace per-char loop with a single add(str, ch.repeat(n)) call.
  The earlier `probe[0] === ch` heuristic was wrong when ch happened to
  equal a leading char of 'probe' (e.g. ch === 'p').
- strftime.ts: revert unrelated typing/structural refactors so the diff
  contains only the memoryLimit threading and the %N memory charge.
- docs: rewire the deleted dos.html sidebar entry to security-model.html
  (with localized labels) so the deleted page does not 404 from the
  sidebar.

Co-authored-by: Cursor <[email protected]>

---------

Co-authored-by: Cursor <[email protected]>

test/integration/filters/date.spec.ts

@@ -204,6 +204,33 @@ describe('filters/date', function () {
       return test('{{ "1990-12-31T23:00:00Z" | date: "%Y-%m-%dT%H:%M:%S" }}', '1991-01-01T04:30:00', undefined, optsWithDateFormat)
     })
   })
+  describe('strftime width / memoryLimit', () => {
+    it('should charge memoryLimit for huge numeric strftime widths', () => {
+      const liquid = new Liquid({ memoryLimit: 500 })
+      expect(() => liquid.parseAndRenderSync('{{ d | date: f }}', { d: 'now', f: '%5000000d' }))
+        .toThrow('memory alloc limit exceeded')
+    })
+    it('should charge memoryLimit for array format PoC', () => {
+      const liquid = new Liquid({ memoryLimit: 50, renderLimit: 1e9 })
+      expect(() => liquid.parseAndRenderSync('{{ d | date: f }}', { d: 'now', f: ['a'.repeat(2000000)] }))
+        .toThrow('memory alloc limit exceeded')
+    })
+    it('should charge memoryLimit for object toString format PoC', () => {
+      const liquid = new Liquid({ memoryLimit: 50, renderLimit: 1e9 })
+      const huge = 'a'.repeat(2000000)
+      const f = { toString: () => huge }
+      expect(() => liquid.parseAndRenderSync('{{ d | date: f }}', { d: 'now', f }))
+        .toThrow('memory alloc limit exceeded')
+    })
+    it('should honor numeric strftime pad width when memoryLimit allows', () => {
+      const liquid = new Liquid({ memoryLimit: 1e7 })
+      const out = liquid.parseAndRenderSync('{{ d | date: f }}', { d: 'now', f: '%5000d' })
+      expect(out.length).toBe(5000)
+      const tight = new Liquid({ memoryLimit: 100 })
+      expect(() => tight.parseAndRenderSync('{{ d | date: f }}', { d: 'now', f: '%5000d' }))
+        .toThrow('memory alloc limit exceeded')
+    })
+  })
 })
 describe('filters/date_to_xmlschema', function () {
   const liquid = new Liquid()