feat(logging): add --log-dir CLI flag to redirect app logs

docs/configuration.md

@@ -159,6 +159,8 @@ Logs rotate by size. When `architect.log` exceeds 10 MiB, it is archived to a ti
 
 Event markers (startup/shutdown and grid/full view transitions) are always recorded at `INFO` level.
 
+Pass `--log-dir <path>` on the command line to write `architect.log` (and its rotated archives) to a custom directory instead of the default location, e.g. `zig build run -- --log-dir /path/to/logs` or `just run --log-dir /path/to/logs`.
+
 ### Worktree Configuration
 
 ```toml

docs/development.md

@@ -58,6 +58,13 @@ just run
 zig build run
 ```
 
+Run with a custom log directory (see `docs/configuration.md` for logging details):
+```bash
+just run --log-dir .tmp/architect-debug-logs
+# or
+zig build run -- --log-dir .tmp/architect-debug-logs
+```
+
 ## Dependencies and Tooling
 
 - **ghostty-vt** is fetched as a pinned tarball via the Zig package manager (`build.zig.zon`).

justfile

@@ -17,11 +17,11 @@ build:
 test:
     zig build test
 
-run:
-    zig build run
+run *args:
+    zig build run -- {{args}}
 
-run-release:
-    zig build run -Doptimize=ReleaseFast
+run-release *args:
+    zig build run -Doptimize=ReleaseFast -- {{args}}
 
 lint:
     #!/usr/bin/env bash

src/app/runtime.zig

@@ -1193,7 +1193,7 @@ fn startQuitFlow(
     return false;
 }
 
-pub fn run() !void {
+pub fn run(log_dir_override: ?[]const u8) !void {
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     defer _ = gpa.deinit();
     const allocator = gpa.allocator();
@@ -1243,6 +1243,7 @@ pub fn run() !void {
     var file_logging_enabled = false;
     logging_mod.init(allocator, .{
         .min_level = config.logging.getMinLevel(),
+        .directory_override = log_dir_override,
     }) catch |err| {
         std.debug.print("Failed to initialize file logging: {}\n", .{err});
     };

src/cli_args.zig

@@ -0,0 +1,53 @@
+const std = @import("std");
+
+pub const ParsedArgs = struct {
+    log_dir_override: ?[]const u8 = null,
+};
+
+pub const ParseError = error{
+    MissingLogDirValue,
+    UnknownArgument,
+};
+
+pub const usage_text = "usage: architect [--log-dir <path>]\n";
+
+/// Parses CLI arguments, excluding argv[0] (the executable path).
+/// Returned slices borrow from `args` and are only valid as long as `args` is.
+pub fn parse(args: []const []const u8) ParseError!ParsedArgs {
+    var result: ParsedArgs = .{};
+    var i: usize = 0;
+    while (i < args.len) : (i += 1) {
+        const arg = args[i];
+        if (std.mem.eql(u8, arg, "--log-dir")) {
+            i += 1;
+            if (i >= args.len) return error.MissingLogDirValue;
+            result.log_dir_override = args[i];
+        } else {
+            return error.UnknownArgument;
+        }
+    }
+    return result;
+}
+
+test "parse with no arguments leaves log_dir_override unset" {
+    const parsed = try parse(&.{});
+    try std.testing.expectEqual(@as(?[]const u8, null), parsed.log_dir_override);
+}
+
+test "parse --log-dir sets log_dir_override" {
+    const parsed = try parse(&.{ "--log-dir", "/tmp/architect-logs" });
+    try std.testing.expectEqualStrings("/tmp/architect-logs", parsed.log_dir_override.?);
+}
+
+test "parse --log-dir without a value returns MissingLogDirValue" {
+    try std.testing.expectError(error.MissingLogDirValue, parse(&.{"--log-dir"}));
+}
+
+test "parse rejects unknown arguments" {
+    try std.testing.expectError(error.UnknownArgument, parse(&.{"--bogus"}));
+}
+
+test "parse takes the last --log-dir when passed multiple times" {
+    const parsed = try parse(&.{ "--log-dir", "/first", "--log-dir", "/second" });
+    try std.testing.expectEqualStrings("/second", parsed.log_dir_override.?);
+}

src/main.zig

@@ -2,6 +2,7 @@ const std = @import("std");
 const builtin = @import("builtin");
 const runtime = @import("app/runtime.zig");
 const logging = @import("logging.zig");
+const cli_args = @import("cli_args.zig");
 
 pub const std_options: std.Options = .{
     // Keep compile-time logging permissive; runtime filtering is handled by
@@ -11,7 +12,16 @@ pub const std_options: std.Options = .{
 };
 
 pub fn main() !void {
-    try runtime.run();
+    const allocator = std.heap.page_allocator;
+    const argv = try std.process.argsAlloc(allocator);
+    defer std.process.argsFree(allocator, argv);
+
+    const parsed = cli_args.parse(argv[1..]) catch |err| {
+        std.debug.print("architect: {s}\n{s}", .{ @errorName(err), cli_args.usage_text });
+        std.process.exit(1);
+    };
+
+    try runtime.run(parsed.log_dir_override);
 }
 
 // Zig only collects tests from files reachable through this block, so every
@@ -27,6 +37,7 @@ test {
     _ = @import("app/layout.zig");
     _ = @import("app/runtime.zig");
     _ = @import("app/terminal_history.zig");
+    _ = @import("cli_args.zig");
     _ = @import("colors.zig");
     _ = @import("config.zig");
     _ = @import("font.zig");