From 8b88b886346460b1ab29edb03ad85bc3bb565a45 Mon Sep 17 00:00:00 2001
From: t <t@tjp.lol>
Date: Tue, 2 Jun 2026 15:00:44 -0600
Subject: compaction

---
 src/config_file.zig | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)

(limited to 'src/config_file.zig')

diff --git a/src/config_file.zig b/src/config_file.zig
index f7589fe..f1ae65f 100644
--- a/src/config_file.zig
+++ b/src/config_file.zig
@@ -158,11 +158,19 @@ pub const Config = struct {
     default_model_ref: ?ModelRef,
     tools: Policy,
     extensions: Policy,
+    /// `[compaction]` settings. `compaction_keep_verbatim` is the kept-
+    /// suffix token budget (null = use libpanto's default). `compaction_model`
+    /// is an owned `<provider>:<alias>` reference string for the optional
+    /// compaction-model override; `compaction_model_ref` slices into it.
+    compaction_keep_verbatim: ?u32 = null,
+    compaction_model: ?[]const u8 = null,
+    compaction_model_ref: ?ModelRef = null,
 
     pub fn deinit(self: *Config) void {
         for (self.providers) |p| p.deinit(self.allocator);
         self.allocator.free(self.providers);
         if (self.default_model) |m| self.allocator.free(m);
+        if (self.compaction_model) |m| self.allocator.free(m);
         self.tools.deinit(self.allocator);
         self.extensions.deinit(self.allocator);
     }
@@ -440,6 +448,25 @@ fn resolve(
         }
     }
 
+    // `[compaction]` settings.
+    var compaction_keep_verbatim: ?u32 = null;
+    var compaction_model: ?[]const u8 = null;
+    errdefer if (compaction_model) |m| allocator.free(m);
+    var compaction_model_ref: ?ModelRef = null;
+    if (root.get("compaction")) |compaction_tbl| {
+        if (compaction_tbl.get("keep_verbatim")) |kv| {
+            if (kv.* == .integer and kv.integer > 0) {
+                compaction_keep_verbatim = @intCast(kv.integer);
+            }
+        }
+        if (compaction_tbl.get("model")) |model_v| {
+            if (model_v.* == .string) {
+                compaction_model = try allocator.dupe(u8, model_v.string);
+                compaction_model_ref = try parseModelRef(compaction_model.?);
+            }
+        }
+    }
+
     const providers_slice = try providers.toOwnedSlice(allocator);
     errdefer {
         for (providers_slice) |p| p.deinit(allocator);
@@ -458,6 +485,18 @@ fn resolve(
         if (!found) return error.UnknownDefaultProvider;
     }
 
+    // Validate the compaction-model override names a provider that resolved.
+    if (compaction_model_ref) |ref| {
+        var found = false;
+        for (providers_slice) |p| {
+            if (std.mem.eql(u8, p.name, ref.provider)) {
+                found = true;
+                break;
+            }
+        }
+        if (!found) return error.UnknownDefaultProvider;
+    }
+
     return .{
         .allocator = allocator,
         .providers = providers_slice,
@@ -465,6 +504,9 @@ fn resolve(
         .default_model_ref = default_model_ref,
         .tools = tools,
         .extensions = extensions,
+        .compaction_keep_verbatim = compaction_keep_verbatim,
+        .compaction_model = compaction_model,
+        .compaction_model_ref = compaction_model_ref,
     };
 }
 
@@ -977,3 +1019,73 @@ test "loadFromPaths: missing files are skipped" {
     try testing.expectEqual(@as(usize, 0), cfg.providers.len);
     try testing.expect(cfg.default_model == null);
 }
+
+test "resolve: [compaction] keep_verbatim and model parse" {
+    const a = testing.allocator;
+    var env = emptyEnv(a);
+    defer env.deinit();
+    try env.put("ANTHROPIC_API_KEY", "sk-ant-xyz");
+
+    const src =
+        \\[providers.anthropic]
+        \\style = "anthropic_messages"
+        \\base_url = "https://api.anthropic.com"
+        \\api_key_env_var = "ANTHROPIC_API_KEY"
+        \\
+        \\[compaction]
+        \\keep_verbatim = 12345
+        \\model = "anthropic:haiku"
+    ;
+    const doc = try parseDoc(a, src);
+    defer doc.deinit();
+
+    var cfg = try resolve(a, &env, doc.root);
+    defer cfg.deinit();
+    try testing.expectEqual(@as(?u32, 12345), cfg.compaction_keep_verbatim);
+    try testing.expectEqualStrings("anthropic:haiku", cfg.compaction_model.?);
+    try testing.expectEqualStrings("anthropic", cfg.compaction_model_ref.?.provider);
+    try testing.expectEqualStrings("haiku", cfg.compaction_model_ref.?.model);
+}
+
+test "resolve: [compaction] absent leaves defaults null" {
+    const a = testing.allocator;
+    var env = emptyEnv(a);
+    defer env.deinit();
+    try env.put("ANTHROPIC_API_KEY", "sk-ant-xyz");
+
+    const src =
+        \\[providers.anthropic]
+        \\style = "anthropic_messages"
+        \\base_url = "https://api.anthropic.com"
+        \\api_key_env_var = "ANTHROPIC_API_KEY"
+    ;
+    const doc = try parseDoc(a, src);
+    defer doc.deinit();
+
+    var cfg = try resolve(a, &env, doc.root);
+    defer cfg.deinit();
+    try testing.expect(cfg.compaction_keep_verbatim == null);
+    try testing.expect(cfg.compaction_model == null);
+    try testing.expect(cfg.compaction_model_ref == null);
+}
+
+test "resolve: [compaction] model naming an unresolved provider errors" {
+    const a = testing.allocator;
+    var env = emptyEnv(a);
+    defer env.deinit();
+    try env.put("ANTHROPIC_API_KEY", "sk-ant-xyz");
+
+    const src =
+        \\[providers.anthropic]
+        \\style = "anthropic_messages"
+        \\base_url = "https://api.anthropic.com"
+        \\api_key_env_var = "ANTHROPIC_API_KEY"
+        \\
+        \\[compaction]
+        \\model = "openai:gpt-4o"
+    ;
+    const doc = try parseDoc(a, src);
+    defer doc.deinit();
+
+    try testing.expectError(error.UnknownDefaultProvider, resolve(a, &env, doc.root));
+}
-- 
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