Add opencode config with custom agent definitions

home/default.nix

@@ -7,6 +7,7 @@
     ./modules/git.nix
     ./modules/tmux.nix
     ./modules/scripts.nix
+    ./modules/opencode.nix
   ];
 
   # ============================================
@@ -32,6 +33,7 @@
     podman-compose
     # AI
     claude-code
+    opencode
 
     # Custom packages
     (pkgs.callPackage ../pkgs/ax {})

home/modules/opencode.nix

@@ -0,0 +1,52 @@
+{ config, ... }:
+
+{
+  xdg.configFile."opencode/opencode.json".text = builtins.toJSON {
+    "$schema" = "https://opencode.ai/config.json";
+    agent = {
+      commit = {
+        description = "Creates a one-line git commit describing the changes";
+        mode = "subagent";
+        model = "openai/gpt-oss-120b:nitro";
+        prompt = ''
+          You are a git commit agent. When invoked:
+          1. Run `git status` and `git diff` to understand all changes
+          2. Stage appropriate files with `git add`
+          3. Create a single one-line commit message that clearly describes the changes
+          4. Never push to remote
+          5. Never use --no-verify or --force flags
+        '';
+        permission = {
+          bash = {
+            "git *" = "allow";
+          };
+          edit = "allow";
+        };
+      };
+      compact = {
+        description = "Compacts and summarizes conversation context to reduce token usage";
+        mode = "subagent";
+        model = "moonshotai/kimi-k2.5:nitro";
+        prompt = ''
+          You are a context compaction specialist. Your job is to summarize and compress the conversation history while preserving:
+          1. Key decisions and their rationale
+          2. Important code changes and their purposes
+          3. Unresolved issues or TODOs
+          4. File paths and line references that are still relevant
+
+          Be extremely concise. Remove:
+          - Redundant explanations
+          - Already-applied code diffs
+          - Exploration steps that didn't lead anywhere
+          - Verbose tool outputs
+
+          Output a dense, information-rich summary that captures the essential state of the conversation.
+        '';
+        permission = {
+          edit = "deny";
+          bash = { "*" = "deny"; };
+        };
+      };
+    };
+  };
+}