fix(#4927): cover the Anthropic tool_use derived push with the persisted fallback

Codex gate: the third derived-push site (Anthropic tool_use content-array branch,
ui.js) still read resultsByTid[tid]||'' without the persisted fallback, so
Anthropic-format sessions could still cold-reload with an empty tool body. Add
the persistedSnippetByTid fallback there too; now all derived result-snippet
reads (OpenAI top-level, Anthropic tool_use, partial) chain to the durable
persisted snippet. Added a guard test asserting EVERY derived resultSnippet read
includes the fallback.

static/ui.js

@@ -11935,7 +11935,7 @@ function renderMessages(options){
           const args=p.input||{};
           const tid=p.id||'';
           const patchSnippet=_cliPatchSnippetFromArgs(name,args);
-          const resultSnippet=resultsByTid[tid]||'';
+          const resultSnippet=resultsByTid[tid]||persistedSnippetByTid[tid]||'';
           const argsSnap=_toolArgsSnapshot(args);
           derived.push(copyLiveToolMetadata({
             name,

tests/test_issue4927_durable_tool_snippet.py

@@ -60,3 +60,20 @@ def test_partial_tool_calls_path_also_falls_back():
         "the partial-tool-calls derived path must also fall back to the "
         "persisted snippet (#4927)"
     )
+
+
+def test_all_derived_result_snippet_reads_have_fallback():
+    """Every derived-push result-snippet READ (OpenAI top-level, Anthropic
+    tool_use content-array, and partial) must include the persisted fallback —
+    a missed branch (e.g. the Anthropic content-array push) would still
+    cold-reload with an empty body (#4927 gate)."""
+    region = _slice_derived_rebuild()
+    # Find every `const resultSnippet=resultsByTid[tid]...` read and assert each
+    # one chains to persistedSnippetByTid.
+    reads = re.findall(r"const resultSnippet=resultsByTid\[tid\][^;]*;", region)
+    assert reads, "no resultSnippet reads found in the derived rebuild"
+    for r in reads:
+        assert "persistedSnippetByTid[tid]" in r, (
+            f"derived resultSnippet read missing the persisted fallback (#4927): {r}"
+        )
+