Move libpanto projects to libpantograph dependencyHEADmain

Remove the in-repo libpanto sources and binding projects from pantograph.
Consume libpantograph through the Zig package URL at
code.tjp.lol/libpantograph.git, including the Lua module artifact used by
CLI extensions.

1 files changed, 0 insertions, 1619 deletions

diff --git a/libpanto/src/anthropic_messages_json.zig b/libpanto/src/anthropic_messages_json.zig
deleted file mode 100644
index 5085149..0000000
--- a/libpanto/src/anthropic_messages_json.zig
+++ /dev/null
@@ -1,1619 +0,0 @@
-//! Anthropic Messages API JSON serialization and event parsing.
-//!
-//! Two responsibilities:
-//!   1. Serialize a `Conversation` into a `/v1/messages` request body.
-//!      Anthropic differs from OpenAI in several ways — see `serializeRequest`.
-//!   2. Parse one streaming SSE event payload (the JSON object after `data: `)
-//!      into a strongly-typed `StreamEvent` that the provider can consume.
-//!
-//! Wire format reference:
-//!   https://platform.claude.com/docs/en/build-with-claude/streaming
-//!   https://platform.claude.com/docs/en/build-with-claude/extended-thinking
-
-const std = @import("std");
-const Allocator = std.mem.Allocator;
-const Writer = std.Io.Writer;
-const conversation = @import("conversation.zig");
-const config_mod = @import("config.zig");
-const tool_registry_mod = @import("tool_registry.zig");
-const writeRawJson = @import("provider.zig").writeRawJson;
-
-// -----------------------------------------------------------------------------
-// Request serialization
-// -----------------------------------------------------------------------------
-
-/// Serialize a Conversation into a `/v1/messages` request body.
-///
-/// Differences from OpenAI Chat Completions:
-///   - System messages are extracted and concatenated into a top-level
-///     `system` string. They do not appear in the `messages` array.
-///   - `content` is always an array of typed blocks, never a bare string.
-///   - `max_tokens` is required.
-///
-/// Caller owns the returned slice.
-pub fn serializeRequest(
-    allocator: Allocator,
-    cfg: *const config_mod.AnthropicMessagesConfig,
-    conv: *const conversation.Conversation,
-    tools: *const tool_registry_mod.ToolRegistry,
-) ![]u8 {
-    var aw: Writer.Allocating = .init(allocator);
-    errdefer aw.deinit();
-
-    var s: std.json.Stringify = .{ .writer = &aw.writer };
-
-    try s.beginObject();
-
-    try s.objectField("model");
-    try s.write(cfg.model);
-
-    try s.objectField("max_tokens");
-    try s.write(cfg.max_tokens);
-
-    try s.objectField("stream");
-    try s.write(true);
-
-    // Extended thinking configuration.
-    // `.disabled`  — omit the field entirely.
-    // `.enabled`   — manual budget: { type, budget_tokens, display }.
-    // `.adaptive`  — adaptive mode: { type, display } + output_config.effort.
-    switch (cfg.thinking) {
-        .disabled => {},
-        .enabled => {
-            // Resolve budget: explicit value or fall back to max_tokens - 1.
-            // Clamp so budget is always strictly less than max_tokens (required
-            // by Anthropic when not using interleaved thinking).
-            const raw_budget: u32 = cfg.thinking_budget_tokens orelse (cfg.max_tokens -| 1);
-            const budget: u32 = if (raw_budget >= cfg.max_tokens) cfg.max_tokens -| 1 else raw_budget;
-            try s.objectField("thinking");
-            try s.beginObject();
-            try s.objectField("type");
-            try s.write("enabled");
-            try s.objectField("budget_tokens");
-            try s.write(budget);
-            try s.objectField("display");
-            try s.write("summarized");
-            try s.endObject();
-        },
-        .adaptive => {
-            try s.objectField("thinking");
-            try s.beginObject();
-            try s.objectField("type");
-            try s.write("adaptive");
-            try s.objectField("display");
-            try s.write("summarized");
-            try s.endObject();
-            try s.objectField("output_config");
-            try s.beginObject();
-            try s.objectField("effort");
-            try s.write(@tagName(cfg.effort));
-            try s.endObject();
-        },
-    }
-
-    // Build and emit the concatenated system prompt, if any.
-    var system_buf: std.ArrayList(u8) = .empty;
-    defer system_buf.deinit(allocator);
-    try collectSystemPrompt(conv, &system_buf, allocator);
-    if (system_buf.items.len > 0) {
-        try s.objectField("system");
-        try s.write(system_buf.items);
-    }
-
-    if (tools.count() > 0) {
-        try s.objectField("tools");
-        try s.beginArray();
-        var it = tools.toolsForLLM();
-        while (it.next()) |t| {
-            try s.beginObject();
-            try s.objectField("name");
-            // `t.decl.name` is already wire-encoded by `toolsForLLM`.
-            try s.write(t.decl.name);
-            try s.objectField("description");
-            try s.write(t.decl.description);
-            try s.objectField("input_schema");
-            try writeRawJson(&s, t.decl.schema_json);
-            try s.endObject();
-        }
-        try s.endArray();
-    }
-
-    // Emit messages (everything that isn't .system). If the conversation
-    // has been compacted, only the latest compaction summary and the
-    // messages after it are active; the superseded prefix is dropped.
-    //
-    // Prompt caching: we replicate Anthropic's "automatic caching" by
-    // placing one `cache_control` breakpoint on the last cacheable block of
-    // the request. Anthropic's native API offers a single top-level
-    // `cache_control` field for this, but Anthropic-style proxies
-    // (Bedrock, Vertex, OpenRouter) reject that field outright (400). A
-    // per-block breakpoint produces the same caching behavior and is the
-    // broadly-supported form, so we mark the block directly. As the
-    // append-only conversation grows, this breakpoint advances each request
-    // and stays well inside the 20-block lookback window, so every turn
-    // reads the prior turn's write and writes only its own new suffix.
-    const window = conversation.activeMessageWindow(conv.messages.items);
-    const cache_at: ?CacheMark = if (cfg.prompt_cache) cacheableTailBlock(window) else null;
-    try s.objectField("messages");
-    try s.beginArray();
-    for (window, 0..) |msg, mi| {
-        if (msg.role == .system) continue;
-        const mark: ?usize = if (cache_at) |c| (if (c.message == mi) c.block else null) else null;
-        try writeMessage(&s, msg, mark, cfg);
-    }
-    try s.endArray();
-
-    try s.endObject();
-
-    return try aw.toOwnedSlice();
-}
-
-/// Build the top-level Anthropic `system` string. Applies the shared
-/// append/replace derivation (see `conversation.effectiveSystemBlocks`),
-/// strips trailing newlines from each surviving block, and joins them with
-/// a horizontal rule (`\n\n---\n\n`). Anthropic's wire format requires a
-/// single string, so this rule is its concession to that constraint.
-fn collectSystemPrompt(
-    conv: *const conversation.Conversation,
-    out: *std.ArrayList(u8),
-    allocator: Allocator,
-) !void {
-    var blocks = try conversation.effectiveSystemBlocks(allocator, conv.messages.items);
-    defer blocks.deinit(allocator);
-
-    const sep = "\n\n---\n\n";
-    var first = true;
-    for (blocks.items) |text| {
-        const trimmed = std.mem.trimEnd(u8, text, "\n");
-        if (!first) try out.appendSlice(allocator, sep);
-        try out.appendSlice(allocator, trimmed);
-        first = false;
-    }
-}
-
-/// Location of the prompt-cache breakpoint: the block to stamp with
-/// `cache_control`. Indices are into the active message window and into
-/// that message's `content` array.
-const CacheMark = struct { message: usize, block: usize };
-
-/// Returns whether a content block can carry a `cache_control` marker and
-/// is actually emitted on the wire. Thinking blocks can't be cached
-/// directly, and unsigned thinking blocks are dropped entirely
-/// (`writeBlock` returns early), so neither is a valid breakpoint target.
-/// System blocks are filtered before emission.
-fn isCacheableBlock(block: conversation.ContentBlock) bool {
-    return switch (block) {
-        .Text, .ToolUse, .ToolResult, .CompactionSummary => true,
-        .Thinking, .System => false,
-    };
-}
-
-/// Find the last cacheable, actually-emitted block in the active window:
-/// the spot to place the single cache breakpoint. Scans messages from the
-/// end, skipping system messages and any trailing non-cacheable blocks
-/// (e.g. a thinking block as the final assistant block). Returns null if
-/// nothing cacheable is present (then no breakpoint is emitted).
-fn cacheableTailBlock(window: []const conversation.Message) ?CacheMark {
-    var mi = window.len;
-    while (mi > 0) {
-        mi -= 1;
-        const msg = window[mi];
-        if (msg.role == .system) continue;
-        var bi = msg.content.items.len;
-        while (bi > 0) {
-            bi -= 1;
-            if (isCacheableBlock(msg.content.items[bi])) {
-                return .{ .message = mi, .block = bi };
-            }
-        }
-    }
-    return null;
-}
-
-fn writeMessage(
-    s: *std.json.Stringify,
-    msg: conversation.Message,
-    cache_block: ?usize,
-    cfg: *const config_mod.AnthropicMessagesConfig,
-) !void {
-    try s.beginObject();
-
-    try s.objectField("role");
-    try s.write(@tagName(msg.role));
-
-    try s.objectField("content");
-    try s.beginArray();
-    for (msg.content.items, 0..) |block, bi| {
-        const mark = if (cache_block) |cb| cb == bi else false;
-        try writeBlock(s, block, mark, cfg, msg.identity);
-    }
-    try s.endArray();
-
-    try s.endObject();
-}
-
-/// Emit a `"cache_control": {"type": "ephemeral"}` field. The caller must
-/// be positioned inside an open block object, after its other fields.
-fn writeCacheControl(s: *std.json.Stringify) !void {
-    try s.objectField("cache_control");
-    try s.beginObject();
-    try s.objectField("type");
-    try s.write("ephemeral");
-    try s.endObject();
-}
-
-fn writeBlock(
-    s: *std.json.Stringify,
-    block: conversation.ContentBlock,
-    mark_cache: bool,
-    cfg: *const config_mod.AnthropicMessagesConfig,
-    msg_identity: ?config_mod.WireIdentity,
-) !void {
-    switch (block) {
-        .Text => |tb| {
-            try s.beginObject();
-            try s.objectField("type");
-            try s.write("text");
-            try s.objectField("text");
-            try s.write(tb.items);
-            if (mark_cache) try writeCacheControl(s);
-            try s.endObject();
-        },
-        .Thinking => |tb| {
-            // Anthropic requires the signature field to round-trip a thinking
-            // block. If we don't have one (e.g. block was synthesized from a
-            // non-Anthropic provider), or if the signature came from a
-            // different provider/model than the current request, skip the
-            // block: Anthropic will reject unsigned thinking on incoming
-            // messages, and opaque signatures are not portable across
-            // provider/model boundaries.
-            const sig = tb.signature orelse return;
-            if (!conversation.thinkingSignatureMatches(tb, msg_identity, .anthropic_messages, cfg.base_url, cfg.model)) return;
-            try s.beginObject();
-            try s.objectField("type");
-            try s.write("thinking");
-            try s.objectField("thinking");
-            try s.write(tb.text.items);
-            try s.objectField("signature");
-            try s.write(sig);
-            try s.endObject();
-        },
-        .ToolUse => |tu| {
-            try s.beginObject();
-            try s.objectField("type");
-            try s.write("tool_use");
-            try s.objectField("id");
-            try s.write(tu.id);
-            try s.objectField("name");
-            // Replayed assistant tool_use: encode the stored dotted name.
-            var name_buf: [tool_registry_mod.max_wire_name_len]u8 = undefined;
-            try s.write(tool_registry_mod.encodeName(&name_buf, tu.name));
-            try s.objectField("input");
-            // Anthropic expects `input` as a nested JSON object, not a
-            // string. The block's input bytes were assembled from
-            // `input_json_delta` fragments — splice them in verbatim.
-            // Treat empty as an empty object.
-            const input_bytes = tu.input.items;
-            if (input_bytes.len == 0) {
-                try s.beginObject();
-                try s.endObject();
-            } else {
-                try writeRawJson(s, input_bytes);
-            }
-            if (mark_cache) try writeCacheControl(s);
-            try s.endObject();
-        },
-        .ToolResult => |tr| {
-            try s.beginObject();
-            try s.objectField("type");
-            try s.write("tool_result");
-            try s.objectField("tool_use_id");
-            try s.write(tr.tool_use_id);
-            // Anthropic supports an `is_error` marker on tool results;
-            // emit it only when set (omitting it defaults to a success
-            // result on the wire).
-            if (tr.is_error) {
-                try s.objectField("is_error");
-                try s.write(true);
-            }
-            // Anthropic accepts `content` as an array of typed blocks:
-            // text, image (base64 source), and document (PDF).
-            try s.objectField("content");
-            try s.beginArray();
-            for (tr.parts.items) |part| {
-                switch (part) {
-                    .text => |tb| {
-                        try s.beginObject();
-                        try s.objectField("type");
-                        try s.write("text");
-                        try s.objectField("text");
-                        try s.write(tb.items);
-                        try s.endObject();
-                    },
-                    .media => |m| {
-                        const is_pdf = std.mem.eql(u8, m.media_type, "application/pdf");
-                        try s.beginObject();
-                        try s.objectField("type");
-                        try s.write(if (is_pdf) "document" else "image");
-                        try s.objectField("source");
-                        try s.beginObject();
-                        try s.objectField("type");
-                        try s.write("base64");
-                        try s.objectField("media_type");
-                        try s.write(m.media_type);
-                        try s.objectField("data");
-                        try s.write(m.data.items);
-                        try s.endObject();
-                        try s.endObject();
-                    },
-                }
-            }
-            try s.endArray();
-            if (mark_cache) try writeCacheControl(s);
-            try s.endObject();
-        },
-        // System blocks never reach here: `serializeRequest` filters out
-        // `.system` messages before emitting the `messages` array, and the
-        // system text is hoisted into the top-level `system` string by
-        // `collectSystemPrompt`. Present only to keep the switch exhaustive.
-        .System => {},
-        // A compaction summary is the synthetic seed text standing in for
-        // a compacted prefix; the model reads it as ordinary user text.
-        .CompactionSummary => |cs| {
-            try s.beginObject();
-            try s.objectField("type");
-            try s.write("text");
-            try s.objectField("text");
-            try s.write(cs.text.items);
-            if (mark_cache) try writeCacheControl(s);
-            try s.endObject();
-        },
-    }
-}
-
-// -----------------------------------------------------------------------------
-// Streaming event parsing
-// -----------------------------------------------------------------------------
-
-/// Parsed shape of one SSE event payload. The `tag` field selects which of
-/// the payload variants is populated.
-///
-/// String slices are borrowed from the underlying `std.json.Parsed`. The
-/// caller must keep `parsed` alive (or copy the slices) until the event is
-/// fully consumed.
-pub const StreamEventTag = enum {
-    message_start,
-    content_block_start,
-    content_block_delta,
-    content_block_stop,
-    message_delta,
-    message_stop,
-    ping,
-    @"error",
-    unknown,
-};
-
-pub const ContentBlockKind = enum { text, thinking, tool_use, unknown };
-
-/// Partial token-count snapshot emitted in `message_start` and
-/// `message_delta`. Field semantics follow Anthropic's wire format:
-///
-///   - `input_tokens`: prompt tokens billed at the base rate.
-///   - `cache_creation_input_tokens`: prompt tokens written to a new
-///     cache entry (1.25× base).
-///   - `cache_read_input_tokens`: prompt tokens served from cache
-///     (0.1× base).
-///   - `output_tokens`: response tokens billed at the output rate.
-///
-/// `message_start.usage` carries the initial input-side counts (output
-/// will be 0 or absent); `message_delta.usage` carries the final
-/// `output_tokens` and may repeat the input-side counts. The provider
-/// merges them — "missing" means "unchanged," not "reset to zero."
-pub const StreamUsage = struct {
-    input_tokens: ?u64 = null,
-    output_tokens: ?u64 = null,
-    cache_creation_input_tokens: ?u64 = null,
-    cache_read_input_tokens: ?u64 = null,
-};
-
-pub const StreamEvent = union(StreamEventTag) {
-    message_start: struct {
-        usage: StreamUsage = .{},
-    },
-    content_block_start: struct {
-        index: usize,
-        kind: ContentBlockKind,
-        // For tool_use blocks (phase 3+):
-        tool_id: ?[]const u8 = null,
-        tool_name: ?[]const u8 = null,
-    },
-    content_block_delta: struct {
-        index: usize,
-        text_delta: ?[]const u8 = null,
-        thinking_delta: ?[]const u8 = null,
-        signature_delta: ?[]const u8 = null,
-        input_json_delta: ?[]const u8 = null,
-    },
-    content_block_stop: struct {
-        index: usize,
-    },
-    message_delta: struct {
-        stop_reason: ?[]const u8 = null,
-        usage: StreamUsage = .{},
-    },
-    message_stop: void,
-    ping: void,
-    @"error": struct {
-        kind: ?[]const u8 = null,
-        message: ?[]const u8 = null,
-    },
-    unknown: void,
-};
-
-pub const ParsedStreamEvent = struct {
-    parsed: std.json.Parsed(std.json.Value),
-    event: StreamEvent,
-
-    pub fn deinit(self: *ParsedStreamEvent) void {
-        self.parsed.deinit();
-    }
-};
-
-pub fn parseStreamEvent(allocator: Allocator, payload: []const u8) !ParsedStreamEvent {
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, payload, .{});
-    errdefer parsed.deinit();
-
-    const root = parsed.value;
-    if (root != .object) return .{ .parsed = parsed, .event = .unknown };
-
-    const type_v = root.object.get("type") orelse return .{ .parsed = parsed, .event = .unknown };
-    if (type_v != .string) return .{ .parsed = parsed, .event = .unknown };
-
-    const ty = type_v.string;
-    if (std.mem.eql(u8, ty, "message_start")) {
-        var usage: StreamUsage = .{};
-        if (root.object.get("message")) |m| {
-            if (m == .object) {
-                if (m.object.get("usage")) |u| {
-                    if (u == .object) usage = parseStreamUsage(u.object);
-                }
-            }
-        }
-        return .{ .parsed = parsed, .event = .{ .message_start = .{ .usage = usage } } };
-    }
-
-    if (std.mem.eql(u8, ty, "content_block_start")) {
-        const idx = readIndex(root) orelse 0;
-        var kind: ContentBlockKind = .unknown;
-        var tool_id: ?[]const u8 = null;
-        var tool_name: ?[]const u8 = null;
-        if (root.object.get("content_block")) |cb| {
-            if (cb == .object) {
-                if (cb.object.get("type")) |t| {
-                    if (t == .string) {
-                        if (std.mem.eql(u8, t.string, "text")) {
-                            kind = .text;
-                        } else if (std.mem.eql(u8, t.string, "thinking")) {
-                            kind = .thinking;
-                        } else if (std.mem.eql(u8, t.string, "tool_use")) {
-                            kind = .tool_use;
-                        }
-                    }
-                }
-                if (cb.object.get("id")) |i| {
-                    if (i == .string) tool_id = i.string;
-                }
-                if (cb.object.get("name")) |n| {
-                    if (n == .string) tool_name = n.string;
-                }
-            }
-        }
-        return .{ .parsed = parsed, .event = .{ .content_block_start = .{
-            .index = idx,
-            .kind = kind,
-            .tool_id = tool_id,
-            .tool_name = tool_name,
-        } } };
-    }
-
-    if (std.mem.eql(u8, ty, "content_block_delta")) {
-        const idx = readIndex(root) orelse 0;
-        var text_delta: ?[]const u8 = null;
-        var thinking_delta: ?[]const u8 = null;
-        var signature_delta: ?[]const u8 = null;
-        var input_json_delta: ?[]const u8 = null;
-        if (root.object.get("delta")) |d| {
-            if (d == .object) {
-                const dt = blk: {
-                    if (d.object.get("type")) |t| {
-                        if (t == .string) break :blk t.string;
-                    }
-                    break :blk "";
-                };
-                if (std.mem.eql(u8, dt, "text_delta")) {
-                    if (d.object.get("text")) |v| if (v == .string) {
-                        text_delta = v.string;
-                    };
-                } else if (std.mem.eql(u8, dt, "thinking_delta")) {
-                    if (d.object.get("thinking")) |v| if (v == .string) {
-                        thinking_delta = v.string;
-                    };
-                } else if (std.mem.eql(u8, dt, "signature_delta")) {
-                    if (d.object.get("signature")) |v| if (v == .string) {
-                        signature_delta = v.string;
-                    };
-                } else if (std.mem.eql(u8, dt, "input_json_delta")) {
-                    if (d.object.get("partial_json")) |v| if (v == .string) {
-                        input_json_delta = v.string;
-                    };
-                }
-            }
-        }
-        return .{ .parsed = parsed, .event = .{ .content_block_delta = .{
-            .index = idx,
-            .text_delta = text_delta,
-            .thinking_delta = thinking_delta,
-            .signature_delta = signature_delta,
-            .input_json_delta = input_json_delta,
-        } } };
-    }
-
-    if (std.mem.eql(u8, ty, "content_block_stop")) {
-        const idx = readIndex(root) orelse 0;
-        return .{ .parsed = parsed, .event = .{ .content_block_stop = .{ .index = idx } } };
-    }
-
-    if (std.mem.eql(u8, ty, "message_delta")) {
-        var stop_reason: ?[]const u8 = null;
-        var usage: StreamUsage = .{};
-        if (root.object.get("delta")) |d| {
-            if (d == .object) {
-                if (d.object.get("stop_reason")) |sr| {
-                    if (sr == .string) stop_reason = sr.string;
-                }
-            }
-        }
-        // `usage` is on the message_delta event itself, not under `delta`.
-        if (root.object.get("usage")) |u| {
-            if (u == .object) usage = parseStreamUsage(u.object);
-        }
-        return .{ .parsed = parsed, .event = .{ .message_delta = .{ .stop_reason = stop_reason, .usage = usage } } };
-    }
-
-    if (std.mem.eql(u8, ty, "message_stop")) {
-        return .{ .parsed = parsed, .event = .message_stop };
-    }
-
-    if (std.mem.eql(u8, ty, "ping")) {
-        return .{ .parsed = parsed, .event = .ping };
-    }
-
-    if (std.mem.eql(u8, ty, "error")) {
-        var kind: ?[]const u8 = null;
-        var message: ?[]const u8 = null;
-        if (root.object.get("error")) |e| {
-            if (e == .object) {
-                if (e.object.get("type")) |t| if (t == .string) {
-                    kind = t.string;
-                };
-                if (e.object.get("message")) |m| if (m == .string) {
-                    message = m.string;
-                };
-            }
-        }
-        return .{ .parsed = parsed, .event = .{ .@"error" = .{ .kind = kind, .message = message } } };
-    }
-
-    return .{ .parsed = parsed, .event = .unknown };
-}
-
-fn parseStreamUsage(obj: std.json.ObjectMap) StreamUsage {
-    return .{
-        .input_tokens = readOptionalU64(obj, "input_tokens"),
-        .output_tokens = readOptionalU64(obj, "output_tokens"),
-        .cache_creation_input_tokens = readOptionalU64(obj, "cache_creation_input_tokens"),
-        .cache_read_input_tokens = readOptionalU64(obj, "cache_read_input_tokens"),
-    };
-}
-
-fn readOptionalU64(obj: std.json.ObjectMap, name: []const u8) ?u64 {
-    const v = obj.get(name) orelse return null;
-    if (v != .integer) return null;
-    if (v.integer < 0) return null;
-    return @intCast(v.integer);
-}
-
-fn readIndex(root: std.json.Value) ?usize {
-    const v = root.object.get("index") orelse return null;
-    if (v != .integer) return null;
-    if (v.integer < 0) return null;
-    return @intCast(v.integer);
-}
-
-// -----------------------------------------------------------------------------
-// Tests
-// -----------------------------------------------------------------------------
-
-const testing = std.testing;
-
-fn testConfig(model: []const u8) config_mod.AnthropicMessagesConfig {
-    return .{
-        .api_key = "k",
-        .base_url = "u",
-        .model = model,
-        .max_tokens = 1024,
-    };
-}
-
-/// Test helper: append a single-text user message. `addUserMessage` now
-/// takes a block slice (symmetric with `addAssistantMessage`); this wraps
-/// the common plain-text case the tests below use.
-fn addUserText(conv: *conversation.Conversation, text: []const u8) !void {
-    const tb = try conversation.textualBlockFromSlice(conv.allocator, text);
-    var block: conversation.ContentBlock = .{ .Text = tb };
-    errdefer block.deinit(conv.allocator);
-    try conv.addUserMessage(&.{block});
-}
-
-test "serializeRequest - system extracted into top-level field" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    try conv.addSystemMessage("You are helpful.");
-    try addUserText(&conv, "Hello!");
-
-    const cfg = testConfig("claude-sonnet-4-20250514");
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-
-    const root = parsed.value.object;
-    try testing.expectEqualStrings("claude-sonnet-4-20250514", root.get("model").?.string);
-    try testing.expect(root.get("stream").?.bool);
-    try testing.expectEqual(@as(i64, 1024), root.get("max_tokens").?.integer);
-    try testing.expectEqualStrings("You are helpful.", root.get("system").?.string);
-
-    // Only the user message appears in `messages`.
-    const msgs = root.get("messages").?.array.items;
-    try testing.expectEqual(@as(usize, 1), msgs.len);
-    try testing.expectEqualStrings("user", msgs[0].object.get("role").?.string);
-
-    // Content is an array of typed blocks, never a bare string.
-    const content = msgs[0].object.get("content").?.array.items;
-    try testing.expectEqual(@as(usize, 1), content.len);
-    try testing.expectEqualStrings("text", content[0].object.get("type").?.string);
-    try testing.expectEqualStrings("Hello!", content[0].object.get("text").?.string);
-}
-
-test "serializeRequest - prompt_cache marks last block with cache_control" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try addUserText(&conv, "Hi");
-
-    var cfg = testConfig("claude-x");
-    cfg.prompt_cache = true;
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    // No top-level field (would break Bedrock/Vertex/OpenRouter).
-    try testing.expect(parsed.value.object.get("cache_control") == null);
-    // The single user text block carries the breakpoint.
-    const block = parsed.value.object.get("messages").?.array.items[0]
-        .object.get("content").?.array.items[0].object;
-    try testing.expectEqualStrings("ephemeral", block.get("cache_control").?.object.get("type").?.string);
-}
-
-test "serializeRequest - cache breakpoint lands on the final block only" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try addUserText(&conv, "first");
-    try conv.addAssistantMessage(&.{
-        .{ .Text = try conversation.textualBlockFromSlice(allocator, "reply") },
-    }, null);
-    try addUserText(&conv, "second");
-
-    var cfg = testConfig("claude-x");
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    const msgs = parsed.value.object.get("messages").?.array.items;
-    try testing.expectEqual(@as(usize, 3), msgs.len);
-    // Only the last message's only block is marked.
-    try testing.expect(msgs[0].object.get("content").?.array.items[0].object.get("cache_control") == null);
-    try testing.expect(msgs[1].object.get("content").?.array.items[0].object.get("cache_control") == null);
-    try testing.expect(msgs[2].object.get("content").?.array.items[0].object.get("cache_control") != null);
-}
-
-test "serializeRequest - cache breakpoint skips a trailing thinking block" {
-    // A thinking block can't carry cache_control; the breakpoint must fall
-    // back to the prior cacheable block (here the assistant text).
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    const sig = try allocator.dupe(u8, "EqQBCgIYAhIM1gbcDa9GJwZA");
-    try conv.addAssistantMessage(&.{
-        .{ .Text = try conversation.textualBlockFromSlice(allocator, "answer") },
-        .{ .Thinking = .{
-            .text = try conversation.textualBlockFromSlice(allocator, "trailing thought"),
-            .signature = sig,
-        } },
-    }, null);
-    try conversation.setThinkingOrigins(allocator, conv.messages.items[0].content.items, .anthropic_messages, "u", "claude-x");
-
-    var cfg = testConfig("claude-x");
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    const content = parsed.value.object.get("messages").?.array.items[0]
-        .object.get("content").?.array.items;
-    // text block marked, thinking block not.
-    try testing.expectEqualStrings("text", content[0].object.get("type").?.string);
-    try testing.expect(content[0].object.get("cache_control") != null);
-    try testing.expectEqualStrings("thinking", content[1].object.get("type").?.string);
-    try testing.expect(content[1].object.get("cache_control") == null);
-}
-
-test "serializeRequest - thinking signature replays from message identity when block origin is absent" {
-    // A reloaded thinking block need not carry its own signature_origin: the
-    // enclosing message's identity is the per-message source of truth, so a
-    // host can rely on it alone (no per-block identity copy required).
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try conv.addAssistantMessage(&.{
-        .{
-            .Thinking = .{
-                .text = try conversation.textualBlockFromSlice(allocator, "reasoned"),
-                .signature = try allocator.dupe(u8, "EqQBCgIYAhIM1gbcDa9GJwZA"),
-                // No signature_origin on the block.
-            },
-        },
-        .{ .Text = try conversation.textualBlockFromSlice(allocator, "answer") },
-    }, null);
-    // Per-message identity matching the request.
-    conv.messages.items[0].identity = try conversation.dupeWireIdentity(allocator, .{
-        .api_style = .anthropic_messages,
-        .base_url = "u",
-        .model = "claude-x",
-    });
-
-    const cfg = testConfig("claude-x");
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    const content = parsed.value.object.get("messages").?.array.items[0]
-        .object.get("content").?.array.items;
-    try testing.expectEqualStrings("thinking", content[0].object.get("type").?.string);
-    try testing.expectEqualStrings("EqQBCgIYAhIM1gbcDa9GJwZA", content[0].object.get("signature").?.string);
-}
-
-test "serializeRequest - thinking dropped when message identity targets a different model" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try conv.addAssistantMessage(&.{
-        .{ .Thinking = .{
-            .text = try conversation.textualBlockFromSlice(allocator, "reasoned"),
-            .signature = try allocator.dupe(u8, "EqQBCgIYAhIM1gbcDa9GJwZA"),
-        } },
-        .{ .Text = try conversation.textualBlockFromSlice(allocator, "answer") },
-    }, null);
-    // Identity points at a *different* model than the request.
-    conv.messages.items[0].identity = try conversation.dupeWireIdentity(allocator, .{
-        .api_style = .anthropic_messages,
-        .base_url = "u",
-        .model = "some-other-model",
-    });
-
-    const cfg = testConfig("claude-x");
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    const content = parsed.value.object.get("messages").?.array.items[0]
-        .object.get("content").?.array.items;
-    // Only the text block survives; the unportable thinking block is dropped.
-    try testing.expectEqual(@as(usize, 1), content.len);
-    try testing.expectEqualStrings("text", content[0].object.get("type").?.string);
-}
-
-test "serializeRequest - prompt_cache disabled omits all cache_control" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try addUserText(&conv, "Hi");
-
-    var cfg = testConfig("claude-x");
-    cfg.prompt_cache = false;
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    try testing.expect(parsed.value.object.get("cache_control") == null);
-    const block = parsed.value.object.get("messages").?.array.items[0]
-        .object.get("content").?.array.items[0].object;
-    try testing.expect(block.get("cache_control") == null);
-}
-
-test "serializeRequest - multiple system messages joined with horizontal rule" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    try conv.addSystemMessage("Be terse.");
-    try conv.addSystemMessage("Be accurate.");
-    try addUserText(&conv, "Hi");
-
-    const cfg = testConfig("claude-x");
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    try testing.expectEqualStrings(
-        "Be terse.\n\n---\n\nBe accurate.",
-        parsed.value.object.get("system").?.string,
-    );
-}
-
-test "serializeRequest - replace-mode system block wipes prior system text" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    try conv.addSystemMessage("original seed");
-    try conv.addSystemMessage("original append");
-    try conv.replaceSystemMessage("fresh seed");
-    try conv.addSystemMessage("fresh append");
-    try addUserText(&conv, "Hi");
-
-    const cfg = testConfig("claude-x");
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    try testing.expectEqualStrings(
-        "fresh seed\n\n---\n\nfresh append",
-        parsed.value.object.get("system").?.string,
-    );
-}
-
-test "serializeRequest - trailing newlines stripped before the rule join" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    try conv.addSystemMessage("line one\n\n");
-    try conv.addSystemMessage("line two\n");
-    try addUserText(&conv, "Hi");
-
-    const cfg = testConfig("claude-x");
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    try testing.expectEqualStrings(
-        "line one\n\n---\n\nline two",
-        parsed.value.object.get("system").?.string,
-    );
-}
-
-test "serializeRequest - no system messages omits the system field" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try addUserText(&conv, "Hi");
-
-    const cfg = testConfig("claude-x");
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    try testing.expect(parsed.value.object.get("system") == null);
-}
-
-test "serializeRequest - signed assistant Thinking blocks round-trip" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    const sig = try allocator.dupe(u8, "EqQBCgIYAhIM1gbcDa9GJwZA");
-    try conv.addAssistantMessage(&.{
-        .{ .Thinking = .{
-            .text = try conversation.textualBlockFromSlice(allocator, "let me think"),
-            .signature = sig,
-        } },
-        .{ .Text = try conversation.textualBlockFromSlice(allocator, "the answer is 42") },
-    }, null);
-    try conversation.setThinkingOrigins(allocator, conv.messages.items[0].content.items, .anthropic_messages, "u", "claude-x");
-
-    const cfg = testConfig("claude-x");
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-
-    const msg = parsed.value.object.get("messages").?.array.items[0];
-    try testing.expectEqualStrings("assistant", msg.object.get("role").?.string);
-
-    const content = msg.object.get("content").?.array.items;
-    try testing.expectEqual(@as(usize, 2), content.len);
-
-    try testing.expectEqualStrings("thinking", content[0].object.get("type").?.string);
-    try testing.expectEqualStrings("let me think", content[0].object.get("thinking").?.string);
-    try testing.expectEqualStrings(
-        "EqQBCgIYAhIM1gbcDa9GJwZA",
-        content[0].object.get("signature").?.string,
-    );
-
-    try testing.expectEqualStrings("text", content[1].object.get("type").?.string);
-    try testing.expectEqualStrings("the answer is 42", content[1].object.get("text").?.string);
-}
-
-test "serializeRequest - mismatched thinking origin drops the block" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    const sig = try allocator.dupe(u8, "EqQBCgIYAhIM1gbcDa9GJwZA");
-    try conv.addAssistantMessage(&.{
-        .{ .Thinking = .{
-            .text = try conversation.textualBlockFromSlice(allocator, "other provider thinking"),
-            .signature = sig,
-        } },
-        .{ .Text = try conversation.textualBlockFromSlice(allocator, "answer") },
-    }, null);
-    try conversation.setThinkingOrigins(allocator, conv.messages.items[0].content.items, .openai_responses, "https://api.individual.githubcopilot.com", "gpt-5.4-mini");
-
-    const cfg = testConfig("claude-x");
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-
-    const content = parsed.value.object.get("messages").?.array.items[0]
-        .object.get("content").?.array.items;
-    try testing.expectEqual(@as(usize, 1), content.len);
-    try testing.expectEqualStrings("text", content[0].object.get("type").?.string);
-}
-
-test "serializeRequest - unsigned Thinking blocks are dropped" {
-    // Anthropic rejects thinking blocks without a valid signature on inbound
-    // messages. If a block lacks one (e.g. from a different provider or an
-    // interrupted stream), omit it rather than send a guaranteed-400 request.
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    try conv.addAssistantMessage(&.{
-        .{ .Thinking = .{
-            .text = try conversation.textualBlockFromSlice(allocator, "unsigned thinking"),
-            .signature = null,
-        } },
-        .{ .Text = try conversation.textualBlockFromSlice(allocator, "answer") },
-    }, null);
-
-    const cfg = testConfig("claude-x");
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-
-    const content = parsed.value.object.get("messages").?.array.items[0]
-        .object.get("content").?.array.items;
-    try testing.expectEqual(@as(usize, 1), content.len);
-    try testing.expectEqualStrings("text", content[0].object.get("type").?.string);
-}
-
-test "parseStreamEvent - message_start" {
-    const allocator = testing.allocator;
-    const payload =
-        \\{"type":"message_start","message":{"id":"msg_1","type":"message","role":"assistant","content":[],"model":"claude","stop_reason":null}}
-    ;
-    var pe = try parseStreamEvent(allocator, payload);
-    defer pe.deinit();
-    try testing.expectEqual(StreamEventTag.message_start, @as(StreamEventTag, pe.event));
-}
-
-test "parseStreamEvent - content_block_start text" {
-    const allocator = testing.allocator;
-    const payload =
-        \\{"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}
-    ;
-    var pe = try parseStreamEvent(allocator, payload);
-    defer pe.deinit();
-    try testing.expectEqual(StreamEventTag.content_block_start, @as(StreamEventTag, pe.event));
-    try testing.expectEqual(@as(usize, 0), pe.event.content_block_start.index);
-    try testing.expectEqual(ContentBlockKind.text, pe.event.content_block_start.kind);
-}
-
-test "parseStreamEvent - content_block_start thinking" {
-    const allocator = testing.allocator;
-    const payload =
-        \\{"type":"content_block_start","index":0,"content_block":{"type":"thinking","thinking":"","signature":""}}
-    ;
-    var pe = try parseStreamEvent(allocator, payload);
-    defer pe.deinit();
-    try testing.expectEqual(ContentBlockKind.thinking, pe.event.content_block_start.kind);
-}
-
-test "parseStreamEvent - text_delta" {
-    const allocator = testing.allocator;
-    const payload =
-        \\{"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":"Hello"}}
-    ;
-    var pe = try parseStreamEvent(allocator, payload);
-    defer pe.deinit();
-    try testing.expectEqual(@as(usize, 1), pe.event.content_block_delta.index);
-    try testing.expectEqualStrings("Hello", pe.event.content_block_delta.text_delta.?);
-    try testing.expect(pe.event.content_block_delta.thinking_delta == null);
-}
-
-test "parseStreamEvent - thinking_delta" {
-    const allocator = testing.allocator;
-    const payload =
-        \\{"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":"step 1"}}
-    ;
-    var pe = try parseStreamEvent(allocator, payload);
-    defer pe.deinit();
-    try testing.expectEqualStrings("step 1", pe.event.content_block_delta.thinking_delta.?);
-}
-
-test "parseStreamEvent - signature_delta" {
-    const allocator = testing.allocator;
-    const payload =
-        \\{"type":"content_block_delta","index":0,"delta":{"type":"signature_delta","signature":"abc123"}}
-    ;
-    var pe = try parseStreamEvent(allocator, payload);
-    defer pe.deinit();
-    try testing.expectEqualStrings("abc123", pe.event.content_block_delta.signature_delta.?);
-}
-
-test "parseStreamEvent - content_block_stop" {
-    const allocator = testing.allocator;
-    const payload =
-        \\{"type":"content_block_stop","index":2}
-    ;
-    var pe = try parseStreamEvent(allocator, payload);
-    defer pe.deinit();
-    try testing.expectEqual(@as(usize, 2), pe.event.content_block_stop.index);
-}
-
-test "parseStreamEvent - message_delta stop_reason" {
-    const allocator = testing.allocator;
-    const payload =
-        \\{"type":"message_delta","delta":{"stop_reason":"end_turn","stop_sequence":null}}
-    ;
-    var pe = try parseStreamEvent(allocator, payload);
-    defer pe.deinit();
-    try testing.expectEqualStrings("end_turn", pe.event.message_delta.stop_reason.?);
-}
-
-test "parseStreamEvent - message_stop" {
-    const allocator = testing.allocator;
-    const payload =
-        \\{"type":"message_stop"}
-    ;
-    var pe = try parseStreamEvent(allocator, payload);
-    defer pe.deinit();
-    try testing.expectEqual(StreamEventTag.message_stop, @as(StreamEventTag, pe.event));
-}
-
-test "parseStreamEvent - ping" {
-    const allocator = testing.allocator;
-    const payload = "{\"type\":\"ping\"}";
-    var pe = try parseStreamEvent(allocator, payload);
-    defer pe.deinit();
-    try testing.expectEqual(StreamEventTag.ping, @as(StreamEventTag, pe.event));
-}
-
-test "parseStreamEvent - error" {
-    const allocator = testing.allocator;
-    const payload =
-        \\{"type":"error","error":{"type":"overloaded_error","message":"too busy"}}
-    ;
-    var pe = try parseStreamEvent(allocator, payload);
-    defer pe.deinit();
-    try testing.expectEqualStrings("overloaded_error", pe.event.@"error".kind.?);
-    try testing.expectEqualStrings("too busy", pe.event.@"error".message.?);
-}
-
-test "parseStreamEvent - unknown type" {
-    const allocator = testing.allocator;
-    const payload =
-        \\{"type":"some_future_event","extra":"data"}
-    ;
-    var pe = try parseStreamEvent(allocator, payload);
-    defer pe.deinit();
-    try testing.expectEqual(StreamEventTag.unknown, @as(StreamEventTag, pe.event));
-}
-
-// -----------------------------------------------------------------------------
-// Phase 3: tools serialization, ToolUse + ToolResult content blocks
-// -----------------------------------------------------------------------------
-
-const tool_mod = @import("tool.zig");
-
-const StaticToolVT = struct {
-    fn invoke(_: *anyopaque, _: []const u8, _: Allocator) anyerror!tool_mod.ResultParts {
-        return error.NotImplementedInTest;
-    }
-    fn deinit_(_: *anyopaque, _: Allocator) void {}
-    const v: tool_mod.Tool.VTable = .{ .invoke = invoke, .deinit = deinit_ };
-};
-var static_tool_ctx_sentinel: u8 = 0;
-fn makeStaticTool(
-    name: []const u8,
-    description: []const u8,
-    schema: []const u8,
-) tool_mod.Tool {
-    return .{
-        .decl = .{
-            .name = name,
-            .description = description,
-            .schema_json = schema,
-        },
-        .ctx = &static_tool_ctx_sentinel,
-        .vtable = &StaticToolVT.v,
-    };
-}
-
-test "serializeRequest - emits tools array when registry non-empty" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try addUserText(&conv, "call something");
-
-    var tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer tools.deinit();
-    try tools.register(makeStaticTool("echo", "Echo a message back.",
-        \\{"type":"object","properties":{"message":{"type":"string"}},"required":["message"]}
-    ));
-
-    const cfg = testConfig("claude-x");
-    const body = try serializeRequest(allocator, &cfg, &conv, &tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-
-    const arr = parsed.value.object.get("tools").?.array.items;
-    try testing.expectEqual(@as(usize, 1), arr.len);
-    try testing.expectEqualStrings("echo", arr[0].object.get("name").?.string);
-    try testing.expectEqualStrings("Echo a message back.", arr[0].object.get("description").?.string);
-
-    const schema = arr[0].object.get("input_schema").?.object;
-    try testing.expectEqualStrings("object", schema.get("type").?.string);
-    try testing.expect(schema.get("properties").? == .object);
-}
-
-test "serializeRequest - dotted names are wire-encoded in tools and history" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    // A prior assistant tool_use replayed from history (dotted internally).
-    const id = try allocator.dupe(u8, "tu_1");
-    const name = try allocator.dupe(u8, "std.write");
-    var input: conversation.TextualBlock = .empty;
-    try input.appendSlice(allocator, "{}");
-    try conv.addAssistantMessage(&.{
-        .{ .ToolUse = .{ .id = id, .name = name, .input = input } },
-    }, null);
-
-    var tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer tools.deinit();
-    try tools.register(makeStaticTool("std.read", "Read.", "{\"type\":\"object\"}"));
-
-    const cfg = testConfig("claude-x");
-    const body = try serializeRequest(allocator, &cfg, &conv, &tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-
-    // Tool list: `std.read` -> `std__read`.
-    const tool_name = parsed.value.object.get("tools").?.array.items[0]
-        .object.get("name").?.string;
-    try testing.expectEqualStrings("std__read", tool_name);
-
-    // Replayed history tool_use: `std.write` -> `std__write`.
-    const hist_name = parsed.value.object.get("messages").?.array.items[0]
-        .object.get("content").?.array.items[0].object.get("name").?.string;
-    try testing.expectEqualStrings("std__write", hist_name);
-}
-
-test "serializeRequest - assistant ToolUse becomes tool_use content block" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    const id = try allocator.dupe(u8, "tu_1");
-    const name = try allocator.dupe(u8, "echo");
-    var input: conversation.TextualBlock = .empty;
-    try input.appendSlice(allocator, "{\"message\":\"hi\"}");
-
-    try conv.addAssistantMessage(&.{
-        .{ .Text = try conversation.textualBlockFromSlice(allocator, "calling tool") },
-        .{ .ToolUse = .{ .id = id, .name = name, .input = input } },
-    }, null);
-
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const cfg = testConfig("claude-x");
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-
-    const content = parsed.value.object.get("messages").?.array.items[0]
-        .object.get("content").?.array.items;
-    try testing.expectEqual(@as(usize, 2), content.len);
-    try testing.expectEqualStrings("text", content[0].object.get("type").?.string);
-
-    try testing.expectEqualStrings("tool_use", content[1].object.get("type").?.string);
-    try testing.expectEqualStrings("tu_1", content[1].object.get("id").?.string);
-    try testing.expectEqualStrings("echo", content[1].object.get("name").?.string);
-    // `input` is a nested JSON object, NOT a string.
-    const inp = content[1].object.get("input").?.object;
-    try testing.expectEqualStrings("hi", inp.get("message").?.string);
-}
-
-test "serializeRequest - user ToolResult becomes tool_result content block" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    const id = try allocator.dupe(u8, "tu_1");
-    var parts: std.ArrayList(conversation.ResultPartStored) = .empty;
-    try parts.append(allocator, .{ .text = try conversation.textualBlockFromSlice(allocator, "the answer is 42") });
-
-    var blocks: std.ArrayList(conversation.ContentBlock) = .empty;
-    try blocks.append(allocator, .{ .ToolResult = .{ .tool_use_id = id, .parts = parts } });
-    try conv.messages.append(allocator, .{ .role = .user, .content = blocks });
-
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const cfg = testConfig("claude-x");
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-
-    const msg = parsed.value.object.get("messages").?.array.items[0].object;
-    try testing.expectEqualStrings("user", msg.get("role").?.string);
-
-    const arr = msg.get("content").?.array.items;
-    try testing.expectEqual(@as(usize, 1), arr.len);
-    try testing.expectEqualStrings("tool_result", arr[0].object.get("type").?.string);
-    try testing.expectEqualStrings("tu_1", arr[0].object.get("tool_use_id").?.string);
-    // A successful result omits the is_error marker entirely.
-    try testing.expect(arr[0].object.get("is_error") == null);
-    const tr_content = arr[0].object.get("content").?.array.items;
-    try testing.expectEqual(@as(usize, 1), tr_content.len);
-    try testing.expectEqualStrings("text", tr_content[0].object.get("type").?.string);
-    try testing.expectEqualStrings("the answer is 42", tr_content[0].object.get("text").?.string);
-}
-
-test "serializeRequest - error ToolResult emits is_error: true" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    const id = try allocator.dupe(u8, "tu_err");
-    var parts: std.ArrayList(conversation.ResultPartStored) = .empty;
-    try parts.append(allocator, .{ .text = try conversation.textualBlockFromSlice(allocator, "file not found") });
-
-    var blocks: std.ArrayList(conversation.ContentBlock) = .empty;
-    try blocks.append(allocator, .{ .ToolResult = .{ .tool_use_id = id, .parts = parts, .is_error = true } });
-    try conv.messages.append(allocator, .{ .role = .user, .content = blocks });
-
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const cfg = testConfig("claude-x");
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-
-    const msg = parsed.value.object.get("messages").?.array.items[0].object;
-    const arr = msg.get("content").?.array.items;
-    try testing.expectEqualStrings("tool_result", arr[0].object.get("type").?.string);
-    try testing.expect(arr[0].object.get("is_error").?.bool);
-}
-
-test "serializeRequest - tool result with image part emits image block" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    const id = try allocator.dupe(u8, "tu_img");
-    var parts: std.ArrayList(conversation.ResultPartStored) = .empty;
-    try parts.append(allocator, .{ .text = try conversation.textualBlockFromSlice(allocator, "the file:") });
-    try parts.append(allocator, .{ .media = .{
-        .media_type = try allocator.dupe(u8, "image/png"),
-        .data = try conversation.textualBlockFromSlice(allocator, "iVBOR=="),
-    } });
-    var blocks: std.ArrayList(conversation.ContentBlock) = .empty;
-    try blocks.append(allocator, .{ .ToolResult = .{ .tool_use_id = id, .parts = parts } });
-    try conv.messages.append(allocator, .{ .role = .user, .content = blocks });
-
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const cfg = testConfig("claude-x");
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-
-    const msg = parsed.value.object.get("messages").?.array.items[0].object;
-    const arr = msg.get("content").?.array.items[0].object.get("content").?.array.items;
-    try testing.expectEqual(@as(usize, 2), arr.len);
-    try testing.expectEqualStrings("text", arr[0].object.get("type").?.string);
-    try testing.expectEqualStrings("image", arr[1].object.get("type").?.string);
-    const src = arr[1].object.get("source").?.object;
-    try testing.expectEqualStrings("base64", src.get("type").?.string);
-    try testing.expectEqualStrings("image/png", src.get("media_type").?.string);
-    try testing.expectEqualStrings("iVBOR==", src.get("data").?.string);
-}
-
-test "serializeRequest - thinking disabled omits thinking and effort fields" {
-    const allocator = testing.allocator;
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try addUserText(&conv, "hi");
-
-    var cfg = testConfig("claude-x");
-    cfg.thinking = .disabled;
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    const root = parsed.value.object;
-    try testing.expect(root.get("thinking") == null);
-    try testing.expect(root.get("effort") == null);
-}
-
-test "serializeRequest - thinking enabled explicit budget" {
-    const allocator = testing.allocator;
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try addUserText(&conv, "hi");
-
-    var cfg = testConfig("claude-x"); // max_tokens = 1024
-    cfg.thinking = .enabled;
-    cfg.thinking_budget_tokens = 500; // within max_tokens
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    const root = parsed.value.object;
-    const th = root.get("thinking").?.object;
-    try testing.expectEqualStrings("enabled", th.get("type").?.string);
-    try testing.expectEqual(@as(i64, 500), th.get("budget_tokens").?.integer);
-    try testing.expectEqualStrings("summarized", th.get("display").?.string);
-    try testing.expect(root.get("effort") == null);
-}
-
-test "serializeRequest - thinking enabled null budget falls back to max_tokens - 1" {
-    const allocator = testing.allocator;
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try addUserText(&conv, "hi");
-
-    var cfg = testConfig("claude-x"); // max_tokens = 1024
-    cfg.thinking = .enabled;
-    cfg.thinking_budget_tokens = null;
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    const th = parsed.value.object.get("thinking").?.object;
-    try testing.expectEqual(@as(i64, 1023), th.get("budget_tokens").?.integer);
-}
-
-test "serializeRequest - thinking enabled budget clamped when >= max_tokens" {
-    const allocator = testing.allocator;
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try addUserText(&conv, "hi");
-
-    var cfg = testConfig("claude-x"); // max_tokens = 1024
-    cfg.thinking = .enabled;
-    cfg.thinking_budget_tokens = 2_000; // > max_tokens
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    const th = parsed.value.object.get("thinking").?.object;
-    // Clamped to max_tokens - 1 = 1023
-    try testing.expectEqual(@as(i64, 1023), th.get("budget_tokens").?.integer);
-}
-
-test "serializeRequest - thinking adaptive default effort" {
-    const allocator = testing.allocator;
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try addUserText(&conv, "hi");
-
-    var cfg = testConfig("claude-x");
-    cfg.thinking = .adaptive;
-    // effort defaults to .medium
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    const root = parsed.value.object;
-    const th = root.get("thinking").?.object;
-    try testing.expectEqualStrings("adaptive", th.get("type").?.string);
-    try testing.expectEqualStrings("summarized", th.get("display").?.string);
-    try testing.expect(th.get("budget_tokens") == null);
-    try testing.expect(root.get("effort") == null);
-    const oc = root.get("output_config").?.object;
-    try testing.expectEqualStrings("medium", oc.get("effort").?.string);
-}
-
-test "serializeRequest - thinking adaptive explicit effort levels" {
-    const allocator = testing.allocator;
-    const efforts = [_]struct { e: config_mod.Effort, name: []const u8 }{
-        .{ .e = .low, .name = "low" },
-        .{ .e = .medium, .name = "medium" },
-        .{ .e = .high, .name = "high" },
-        .{ .e = .xhigh, .name = "xhigh" },
-        .{ .e = .max, .name = "max" },
-    };
-    for (efforts) |entry| {
-        var conv = conversation.Conversation.init(allocator);
-        defer conv.deinit();
-        try addUserText(&conv, "hi");
-
-        var cfg = testConfig("claude-x");
-        cfg.thinking = .adaptive;
-        cfg.effort = entry.e;
-        var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-        defer empty_tools.deinit();
-        const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-        defer allocator.free(body);
-
-        var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-        defer parsed.deinit();
-        const oc = parsed.value.object.get("output_config").?.object;
-        try testing.expectEqualStrings(entry.name, oc.get("effort").?.string);
-    }
-}
-
-test "serializeRequest - thinking adaptive ignores budget_tokens" {
-    const allocator = testing.allocator;
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-    try addUserText(&conv, "hi");
-
-    var cfg = testConfig("claude-x");
-    cfg.thinking = .adaptive;
-    cfg.thinking_budget_tokens = 9_999; // should be ignored
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-    const th = parsed.value.object.get("thinking").?.object;
-    try testing.expect(th.get("budget_tokens") == null);
-}
-
-test "serializeRequest - empty ToolUse input becomes {} not invalid JSON" {
-    const allocator = testing.allocator;
-
-    var conv = conversation.Conversation.init(allocator);
-    defer conv.deinit();
-
-    const id = try allocator.dupe(u8, "tu_1");
-    const name = try allocator.dupe(u8, "noargs");
-    try conv.addAssistantMessage(&.{
-        .{ .ToolUse = .{ .id = id, .name = name, .input = .empty } },
-    }, null);
-
-    var empty_tools = tool_registry_mod.ToolRegistry.init(allocator);
-    defer empty_tools.deinit();
-    const cfg = testConfig("claude-x");
-    const body = try serializeRequest(allocator, &cfg, &conv, &empty_tools);
-    defer allocator.free(body);
-
-    var parsed = try std.json.parseFromSlice(std.json.Value, allocator, body, .{});
-    defer parsed.deinit();
-
-    const tu = parsed.value.object.get("messages").?.array.items[0]
-        .object.get("content").?.array.items[0].object;
-    try testing.expectEqualStrings("tool_use", tu.get("type").?.string);
-    try testing.expect(tu.get("input").? == .object);
-    try testing.expectEqual(@as(usize, 0), tu.get("input").?.object.count());
-}