opencode.json: an implement agent for unattended runs; run-plan uses it

From the combined Ornith guidance (§8.2), checked against OpenCode
1.18.30's schema and permission docs (last matching rule wins). Reads
and edits outside the repository are denied, except OpenCode's own
tool-output and temporary directories; web access, questions, subagents
and doom-loop prompts are denied; edits to AGENTS.md, CLAUDE.md,
opencode.json, the design documents, specs, plans and tools/ are denied;
shell commands are allowed except push, reset, rebase, amend, switch,
checkout, find /, locate, sudo, rm -rf / and curl/wget. A denied call
continues the loop (experimental.continue_loop_on_deny, untested with
Ornith). steps = 400 is a backstop. No custom prompt: OpenCode already
reads AGENTS.md, and a prompt may replace its tool guidance.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

opencode.json

@@ -0,0 +1,57 @@
+{
+  "$schema": "https://opencode.ai/config.json",
+  "autoupdate": false,
+  "share": "disabled",
+  "permission": {
+    "external_directory": {
+      "*": "deny",
+      "~/.local/share/opencode/tool-output/*": "allow",
+      "/var/folders/*/T/opencode/*": "allow",
+      "/tmp/opencode/*": "allow"
+    },
+    "webfetch": "deny",
+    "websearch": "deny",
+    "question": "deny",
+    "task": "deny",
+    "doom_loop": "deny",
+    "edit": {
+      "*": "allow",
+      "AGENTS.md": "deny",
+      "CLAUDE.md": "deny",
+      "opencode.json": "deny",
+      "docs/design.md": "deny",
+      "docs/decisions.md": "deny",
+      "docs/inference-contract.md": "deny",
+      "docs/specs/**": "deny",
+      "docs/plans/**": "deny",
+      "tools/**": "deny"
+    },
+    "bash": {
+      "*": "allow",
+      "git push*": "deny",
+      "git reset*": "deny",
+      "git rebase*": "deny",
+      "git commit --amend*": "deny",
+      "git switch*": "deny",
+      "git checkout*": "deny",
+      "find /*": "deny",
+      "locate *": "deny",
+      "sudo *": "deny",
+      "rm -rf /*": "deny",
+      "curl *": "deny",
+      "wget *": "deny"
+    }
+  },
+  "experimental": {
+    "continue_loop_on_deny": true
+  },
+  "agent": {
+    "implement": {
+      "description": "Implements exactly one closed task file from docs/plans, then commits and logs it.",
+      "mode": "primary",
+      "temperature": 0.6,
+      "top_p": 0.95,
+      "steps": 400
+    }
+  }
+}