chore(config): bump default anthropic model to claude-sonnet-5

DEFAULT_MODELS[anthropic] (and thus FALLBACK_MODEL) -> anthropic/claude-sonnet-5,
matching the .env.example bump. openai/amazon-bedrock defaults unchanged.
Documented under CHANGELOG Unreleased (no release cut yet).

CHANGELOG.md

@@ -6,6 +6,18 @@ Tags follow **independent semver** (since `v2.0.0`) — they version *this image
 
 ---
 
+## Unreleased
+
+### Changed
+
+- **Default Anthropic model bumped to `claude-sonnet-5`** (was
+  `claude-sonnet-4-6`). Updated `DEFAULT_MODELS["anthropic"]` in
+  `rootfs/usr/local/lib/opencode-devbox/generate-config.py` (which also feeds
+  `FALLBACK_MODEL`) and the commented `OPENCODE_MODEL` example in `.env.example`.
+  Takes effect for new containers when `OPENCODE_PROVIDER=anthropic` and no
+  explicit `OPENCODE_MODEL` override is set. The `openai` and `amazon-bedrock`
+  provider defaults are unchanged.
+
 ## v2.7.0 — 2026-07-13
 
 Minor release. Headline: **further parity with the sibling `pi-devbox` image** —

rootfs/usr/local/lib/opencode-devbox/generate-config.py

@@ -41,7 +41,7 @@ from pathlib import Path
 
 # Default model per provider. Update here when upstream changes.
 DEFAULT_MODELS: dict[str, str] = {
-    "anthropic": "anthropic/claude-sonnet-4-6",
+    "anthropic": "anthropic/claude-sonnet-5",
     "openai": "openai/gpt-5.4",
     "amazon-bedrock": (
         "amazon-bedrock/global.anthropic.claude-sonnet-4-5-20250929-v1:0"