cli: rework +ssh-cache internals and user interface (#12814)

This change primarily focused on a revised +ssh-cache user interface,
but it also reworks a bunch of the internals.

The primary CLI improvement is support for positional arguments and a
consistent list output format that includes both the ISO-formatted
timestamp and relative age.

ghostty +ssh-cache # List all cached destinations
    ghostty +ssh-cache user@example.com          # Show that destination
ghostty +ssh-cache example.com # Show all users on that host
ghostty +ssh-cache --add=user@example.com # Manually add a destination
    ghostty +ssh-cache --remove=user@example.com # Remove a destination
ghostty +ssh-cache --prune=30d # Remove entries older than 30 days
    ghostty +ssh-cache --clear                   # Clear entire cache

Notable, we now support a --prune operation that replaces the previous
--expire-days flag that was never actually hooked up to anything (!!).
--prune also supports a wider range of Duration-based values.

We're also much more consistent with error codes: 0=success, 1=failure,
2=usage.

While working on those changes, I also reworked the cache internals,
particularly the code around timestamp handling and errors. For example,
I dropped the explicit error sets because they were growing unwieldy,
and in practice we only matched on a subset of those errors.

Lastly, overall test coverage should be much improved, especially around
the time- and allocation-related operations.

---

*AI Disclosure:* I made a lot of iterative, AI-assisted (Claude Opus
4.7) correctness passes over this work. It was particularly helpful in
tracing through the various failure modes, and it wrote those unit tests
in the process.

src/cli/ssh-cache/DiskCache.zig

@@ -17,14 +17,6 @@ const MAX_CACHE_SIZE = 512 * 1024;
 /// Path to a file where the cache is stored.
 path: []const u8,
 
-pub const DefaultPathError = Allocator.Error || error{
-    /// The general error that is returned for any filesystem error
-    /// that may have resulted in the XDG lookup failing.
-    XdgLookupFailed,
-};
-
-pub const Error = error{ CacheIsLocked, HostnameIsInvalid };
-
 /// Returns the default path for the cache for a given program.
 ///
 /// On all platforms, this is `${XDG_STATE_HOME}/ghostty/ssh_cache`.
@@ -33,7 +25,7 @@ pub const Error = error{ CacheIsLocked, HostnameIsInvalid };
 pub fn defaultPath(
     alloc: Allocator,
     program: []const u8,
-) DefaultPathError![]const u8 {
+) ![]const u8 {
     const state_dir: []const u8 = xdg.state(
         alloc,
         .{ .subdir = program },
@@ -55,27 +47,15 @@ pub fn clear(self: DiskCache) !void {
     };
 }
 
-pub const AddResult = enum { added, updated };
+/// Add or update an entry in the cache, recording `timestamp` (Unix seconds).
-
-pub const AddError = std.fs.Dir.MakeError ||
-    std.fs.Dir.StatFileError ||
-    std.fs.File.OpenError ||
-    std.fs.File.ChmodError ||
-    std.io.Reader.LimitedAllocError ||
-    FixupPermissionsError ||
-    ReadEntriesError ||
-    WriteCacheFileError ||
-    Error;
-
-/// Add or update a hostname entry in the cache.
-/// Returns AddResult.added for new entries or AddResult.updated for existing ones.
 /// The cache file is created if it doesn't exist with secure permissions (0600).
 pub fn add(
     self: DiskCache,
     alloc: Allocator,
-    hostname: []const u8,
+    key: []const u8,
-) AddError!AddResult {
+    timestamp: i64,
-    if (!isValidCacheKey(hostname)) return error.HostnameIsInvalid;
+) !void {
+    if (!isValidCacheKey(key)) return error.InvalidCacheKey;
 
     // Create cache directory if needed
     if (std.fs.path.dirname(self.path)) |dir| {
@@ -107,58 +87,49 @@ pub fn add(
     // Lock
     // Causes a compile failure in the Zig std library on Windows, see:
     // https://github.com/ziglang/zig/issues/18430
-    if (comptime builtin.os.tag != .windows) _ = file.tryLock(.exclusive) catch return error.CacheIsLocked;
+    if (comptime builtin.os.tag != .windows) _ = file.tryLock(.exclusive) catch return error.CacheLocked;
     defer if (comptime builtin.os.tag != .windows) file.unlock();
 
     var entries = try readEntries(alloc, file);
     defer deinitEntries(alloc, &entries);
 
-    // Add or update entry
+    // Update the timestamp of an existing entry, or insert a new one. For a
-    const gop = try entries.getOrPut(hostname);
+    // new entry, dupe both strings up front so a failed allocation never
-    const result: AddResult = if (!gop.found_existing) add: {
+    // leaves a half-built slot (borrowed key, undefined value) for the
-        const hostname_copy = try alloc.dupe(u8, hostname);
+    // `deinitEntries` defer to walk.
-        errdefer alloc.free(hostname_copy);
+    if (entries.getPtr(key)) |existing| {
+        existing.timestamp = timestamp;
+    } else {
+        const key_copy = try alloc.dupe(u8, key);
+        errdefer alloc.free(key_copy);
         const terminfo_copy = try alloc.dupe(u8, "xterm-ghostty");
         errdefer alloc.free(terminfo_copy);
 
-        gop.key_ptr.* = hostname_copy;
+        try entries.put(key_copy, .{
-        gop.value_ptr.* = .{
+            .hostname = key_copy,
-            .hostname = gop.key_ptr.*,
+            .timestamp = timestamp,
-            .timestamp = std.time.timestamp(),
             .terminfo_version = terminfo_copy,
-        };
+        });
-        break :add .added;
+    }
-    } else update: {
-        // Update timestamp for existing entry
-        gop.value_ptr.timestamp = std.time.timestamp();
-        break :update .updated;
-    };
 
-    try self.writeCacheFile(entries, null);
+    try self.writeCacheFile(entries);
-    return result;
 }
 
-pub const RemoveError = std.fs.File.OpenError ||
+/// Remove an entry from the cache. Returns true if an entry was removed,
-    FixupPermissionsError ||
+/// false if the key wasn't present (or the cache file is missing).
-    ReadEntriesError ||
-    WriteCacheFileError ||
-    Error;
-
-/// Remove a hostname entry from the cache.
-/// No error is returned if the hostname doesn't exist or the cache file is missing.
 pub fn remove(
     self: DiskCache,
     alloc: Allocator,
-    hostname: []const u8,
+    key: []const u8,
-) RemoveError!void {
+) !bool {
-    if (!isValidCacheKey(hostname)) return error.HostnameIsInvalid;
+    if (!isValidCacheKey(key)) return error.InvalidCacheKey;
 
     // Open our file
     const file = std.fs.openFileAbsolute(
         self.path,
         .{ .mode = .read_write },
     ) catch |err| switch (err) {
-        error.FileNotFound => return,
+        error.FileNotFound => return false,
         else => return err,
     };
     defer file.close();
@@ -167,7 +138,7 @@ pub fn remove(
     // Lock
     // Causes a compile failure in the Zig std library on Windows, see:
     // https://github.com/ziglang/zig/issues/18430
-    if (comptime builtin.os.tag != .windows) _ = file.tryLock(.exclusive) catch return error.CacheIsLocked;
+    if (comptime builtin.os.tag != .windows) _ = file.tryLock(.exclusive) catch return error.CacheLocked;
     defer if (comptime builtin.os.tag != .windows) file.unlock();
 
     // Read existing entries
@@ -175,27 +146,73 @@ pub fn remove(
     defer deinitEntries(alloc, &entries);
 
     // Remove the entry if it exists and ensure we free the memory
-    if (entries.fetchRemove(hostname)) |kv| {
+    const removed = if (entries.fetchRemove(key)) |kv| removed: {
+        assert(kv.key.ptr == kv.value.hostname.ptr);
+        alloc.free(kv.value.hostname);
+        alloc.free(kv.value.terminfo_version);
+        break :removed true;
+    } else false;
+
+    try self.writeCacheFile(entries);
+    return removed;
+}
+
+/// Remove all entries older than `max_age_s` seconds and return how many
+/// were pruned. Returns zero (and nothing written) if the cache file is
+/// missing.
+pub fn prune(
+    self: DiskCache,
+    alloc: Allocator,
+    max_age_s: u64,
+) !usize {
+    const file = std.fs.openFileAbsolute(
+        self.path,
+        .{ .mode = .read_write },
+    ) catch |err| switch (err) {
+        error.FileNotFound => return 0,
+        else => return err,
+    };
+    defer file.close();
+    try fixupPermissions(file);
+
+    // Lock
+    // Causes a compile failure in the Zig std library on Windows, see:
+    // https://github.com/ziglang/zig/issues/18430
+    if (comptime builtin.os.tag != .windows) _ = file.tryLock(.exclusive) catch return error.CacheLocked;
+    defer if (comptime builtin.os.tag != .windows) file.unlock();
+
+    // Read existing entries
+    var entries = try readEntries(alloc, file);
+    defer deinitEntries(alloc, &entries);
+
+    // Drop expired entries from the map, then persist what remains.
+    const now = std.time.timestamp();
+    var expired: std.ArrayList([]const u8) = .empty;
+    defer expired.deinit(alloc);
+    var iter = entries.iterator();
+    while (iter.next()) |kv| {
+        const age_s = now -| kv.value_ptr.timestamp;
+        if (age_s > max_age_s) try expired.append(alloc, kv.key_ptr.*);
+    }
+    for (expired.items) |key| {
+        const kv = entries.fetchRemove(key).?;
         assert(kv.key.ptr == kv.value.hostname.ptr);
         alloc.free(kv.value.hostname);
         alloc.free(kv.value.terminfo_version);
     }
 
-    try self.writeCacheFile(entries, null);
+    try self.writeCacheFile(entries);
+    return expired.items.len;
 }
 
-pub const ContainsError = std.fs.File.OpenError ||
+/// Check if a key exists in the cache.
-    ReadEntriesError ||
-    error{HostnameIsInvalid};
-
-/// Check if a hostname exists in the cache.
 /// Returns false if the cache file doesn't exist.
 pub fn contains(
     self: DiskCache,
     alloc: Allocator,
-    hostname: []const u8,
+    key: []const u8,
-) ContainsError!bool {
+) !bool {
-    if (!isValidCacheKey(hostname)) return error.HostnameIsInvalid;
+    if (!isValidCacheKey(key)) return error.InvalidCacheKey;
 
     // Open our file
     const file = std.fs.openFileAbsolute(
@@ -211,12 +228,10 @@ pub fn contains(
     var entries = try readEntries(alloc, file);
     defer deinitEntries(alloc, &entries);
 
-    return entries.contains(hostname);
+    return entries.contains(key);
 }
 
-pub const FixupPermissionsError = (std.fs.File.StatError || std.fs.File.ChmodError);
+fn fixupPermissions(file: std.fs.File) !void {
-
-fn fixupPermissions(file: std.fs.File) FixupPermissionsError!void {
     // Windows does not support chmod
     if (comptime builtin.os.tag == .windows) return;
 
@@ -228,18 +243,10 @@ fn fixupPermissions(file: std.fs.File) FixupPermissionsError!void {
     }
 }
 
-pub const WriteCacheFileError = std.fs.Dir.OpenError ||
-    std.fs.AtomicFile.InitError ||
-    std.fs.AtomicFile.FlushError ||
-    std.fs.AtomicFile.FinishError ||
-    Entry.FormatError ||
-    error{InvalidCachePath};
-
 fn writeCacheFile(
     self: DiskCache,
     entries: std.StringHashMap(Entry),
-    expire_days: ?u32,
+) !void {
-) WriteCacheFileError!void {
     const cache_dir = std.fs.path.dirname(self.path) orelse return error.InvalidCachePath;
     const cache_basename = std.fs.path.basename(self.path);
 
@@ -255,8 +262,6 @@ fn writeCacheFile(
 
     var iter = entries.iterator();
     while (iter.next()) |kv| {
-        // Only write non-expired entries
-        if (kv.value_ptr.isExpired(expire_days)) continue;
         try kv.value_ptr.format(&atomic_file.file_writer.interface);
     }
 
@@ -299,12 +304,10 @@ pub fn deinitEntries(
     entries.deinit();
 }
 
-pub const ReadEntriesError = std.mem.Allocator.Error || std.io.Reader.LimitedAllocError;
-
 fn readEntries(
     alloc: Allocator,
     file: std.fs.File,
-) ReadEntriesError!std.StringHashMap(Entry) {
+) !std.StringHashMap(Entry) {
     var reader = file.reader(&.{});
     const content = try reader.interface.allocRemaining(
         alloc,
@@ -365,7 +368,7 @@ fn readEntries(
 }
 
 // Supports both standalone hostnames and user@hostname format
-fn isValidCacheKey(key: []const u8) bool {
+pub fn isValidCacheKey(key: []const u8) bool {
     if (key.len == 0) return false;
 
     // Check for user@hostname format
@@ -463,33 +466,23 @@ test "disk cache operations" {
     const path = try tmp.dir.realpathAlloc(alloc, "cache");
     defer alloc.free(path);
 
-    // Setup our cache
+    // Setup our cache. Adding the same key twice exercises both the new
+    // and existing-entry paths.
     const cache: DiskCache = .{ .path = path };
-    try testing.expectEqual(
+    try cache.add(alloc, "example.com", std.time.timestamp());
-        AddResult.added,
+    try cache.add(alloc, "example.com", std.time.timestamp());
-        try cache.add(alloc, "example.com"),
+    try testing.expect(try cache.contains(alloc, "example.com"));
-    );
-    try testing.expectEqual(
-        AddResult.updated,
-        try cache.add(alloc, "example.com"),
-    );
-    try testing.expect(
-        try cache.contains(alloc, "example.com"),
-    );
 
     // List
     var entries = try cache.list(alloc);
     deinitEntries(alloc, &entries);
 
-    // Remove
+    // Remove reports that it removed the entry, and a second remove of the
-    try cache.remove(alloc, "example.com");
+    // same key reports nothing to remove.
-    try testing.expect(
+    try testing.expect(try cache.remove(alloc, "example.com"));
-        !(try cache.contains(alloc, "example.com")),
+    try testing.expect(!try cache.remove(alloc, "example.com"));
-    );
+    try testing.expect(!(try cache.contains(alloc, "example.com")));
-    try testing.expectEqual(
+    try cache.add(alloc, "example.com", std.time.timestamp());
-        AddResult.added,
-        try cache.add(alloc, "example.com"),
-    );
 }
 
 test "disk cache cleans up temp files" {
@@ -505,8 +498,8 @@ test "disk cache cleans up temp files" {
     defer alloc.free(cache_path);
 
     const cache: DiskCache = .{ .path = cache_path };
-    try testing.expectEqual(AddResult.added, try cache.add(alloc, "example.com"));
+    try cache.add(alloc, "example.com", std.time.timestamp());
-    try testing.expectEqual(AddResult.added, try cache.add(alloc, "example.org"));
+    try cache.add(alloc, "example.org", std.time.timestamp());
 
     // Verify only the cache file exists and no temp files left behind
     var count: usize = 0;
@@ -518,6 +511,55 @@ test "disk cache cleans up temp files" {
     try testing.expectEqual(1, count);
 }
 
+test "disk cache prune" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var tmp = testing.tmpDir(.{});
+    defer tmp.cleanup();
+    const tmp_path = try tmp.dir.realpathAlloc(alloc, ".");
+    defer alloc.free(tmp_path);
+    const cache_path = try std.fs.path.join(alloc, &.{ tmp_path, "cache" });
+    defer alloc.free(cache_path);
+
+    const cache: DiskCache = .{ .path = cache_path };
+
+    // Back-date one entry an hour old and one 100 days old.
+    const day = std.time.s_per_day;
+    const hour = std.time.s_per_hour;
+    const now = std.time.timestamp();
+    try cache.add(alloc, "recent.com", now - hour);
+    try cache.add(alloc, "old.com", now - 100 * day);
+
+    // Prune entries older than 90 days: only old.com goes.
+    try testing.expectEqual(@as(usize, 1), try cache.prune(alloc, 90 * day));
+    try testing.expect(try cache.contains(alloc, "recent.com"));
+    try testing.expect(!try cache.contains(alloc, "old.com"));
+
+    // Pruning again removes nothing.
+    try testing.expectEqual(@as(usize, 0), try cache.prune(alloc, 90 * day));
+
+    // Sub-day granularity: a 30-minute max age prunes the hour-old entry.
+    try testing.expectEqual(@as(usize, 1), try cache.prune(alloc, 30 * std.time.s_per_min));
+    try testing.expect(!try cache.contains(alloc, "recent.com"));
+}
+
+test "disk cache prune missing file" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var tmp = testing.tmpDir(.{});
+    defer tmp.cleanup();
+
+    const tmp_path = try tmp.dir.realpathAlloc(alloc, ".");
+    defer alloc.free(tmp_path);
+    const cache_path = try std.fs.path.join(alloc, &.{ tmp_path, "cache" });
+    defer alloc.free(cache_path);
+
+    const cache: DiskCache = .{ .path = cache_path };
+    try testing.expectEqual(@as(usize, 0), try cache.prune(alloc, 30));
+}
+
 test "disk cache reads duplicate keys" {
     const testing = std.testing;
     const alloc = testing.allocator;
@@ -600,6 +642,39 @@ test "disk cache reads survive allocation failure" {
     }
 }
 
+test "disk cache add survives allocation failure" {
+    const testing = std.testing;
+
+    var tmp = testing.tmpDir(.{});
+    defer tmp.cleanup();
+    const tmp_path = try tmp.dir.realpathAlloc(testing.allocator, ".");
+    defer testing.allocator.free(tmp_path);
+    const path = try std.fs.path.join(testing.allocator, &.{ tmp_path, "cache" });
+    defer testing.allocator.free(path);
+
+    const cache: DiskCache = .{ .path = path };
+
+    // Fail the Nth allocation for every N until add completes. A failed add
+    // must not leak or leave a half-built map entry. The FailingAllocator
+    // is backed by testing.allocator to catch either. Each iteration starts
+    // from a clean cache file.
+    var fail_index: usize = 0;
+    while (true) : (fail_index += 1) {
+        std.fs.cwd().deleteFile(path) catch {};
+        var failing = std.testing.FailingAllocator.init(
+            testing.allocator,
+            .{ .fail_index = fail_index },
+        );
+        const alloc = failing.allocator();
+
+        if (cache.add(alloc, "user@example.com", 100)) |_| {
+            if (!failing.has_induced_failure) break;
+        } else |err| {
+            try testing.expectEqual(error.OutOfMemory, err);
+        }
+    }
+}
+
 test isValidHost {
     const testing = std.testing;
 

src/cli/ssh-cache/Entry.zig

@@ -42,61 +42,6 @@ pub fn format(self: Entry, writer: *std.Io.Writer) FormatError!void {
     );
 }
 
-pub fn isExpired(self: Entry, expire_days_: ?u32) bool {
-    const expire_days = expire_days_ orelse return false;
-    const now = std.time.timestamp();
-    const age_days = @divTrunc(now -| self.timestamp, std.time.s_per_day);
-    return age_days > expire_days;
-}
-
-test "cache entry expiration" {
-    const testing = std.testing;
-    const now = std.time.timestamp();
-
-    const fresh_entry: Entry = .{
-        .hostname = "test.com",
-        .timestamp = now - std.time.s_per_day, // 1 day old
-        .terminfo_version = "xterm-ghostty",
-    };
-    try testing.expect(!fresh_entry.isExpired(90));
-
-    const old_entry: Entry = .{
-        .hostname = "old.com",
-        .timestamp = now - (std.time.s_per_day * 100), // 100 days old
-        .terminfo_version = "xterm-ghostty",
-    };
-    try testing.expect(old_entry.isExpired(90));
-
-    // Test never-expire case
-    try testing.expect(!old_entry.isExpired(null));
-}
-
-test "cache entry expiration exact boundary" {
-    const testing = std.testing;
-    const now = std.time.timestamp();
-
-    // Exactly at expiration boundary
-    const boundary_entry: Entry = .{
-        .hostname = "example.com",
-        .timestamp = now - (std.time.s_per_day * 30),
-        .terminfo_version = "xterm-ghostty",
-    };
-    try testing.expect(!boundary_entry.isExpired(30));
-    try testing.expect(boundary_entry.isExpired(29));
-}
-
-test "cache entry expiration large timestamp" {
-    const testing = std.testing;
-    const now = std.time.timestamp();
-
-    const boundary_entry: Entry = .{
-        .hostname = "example.com",
-        .timestamp = now + (std.time.s_per_day * 30),
-        .terminfo_version = "xterm-ghostty",
-    };
-    try testing.expect(!boundary_entry.isExpired(30));
-}
-
 test "cache entry parsing valid formats" {
     const testing = std.testing;
 

src/cli/ssh.zig

@@ -302,7 +302,7 @@ fn runInner(
 
     // Attempt to cache (if needed) on a successful ssh execution.
     if (exit_code == 0) if (session.to_cache) |entry| {
-        if (entry.cache.add(alloc, entry.dest)) |_| {
+        if (entry.cache.add(alloc, entry.dest, std.time.timestamp())) |_| {
             verbosePrint(opts, stderr, "cache: wrote {s}", .{entry.dest});
         } else |err| {
             log.debug("cache add failed for '{s}': {}", .{ entry.dest, err });

src/cli/ssh_cache.zig

@@ -3,6 +3,7 @@ const fs = std.fs;
 const Allocator = std.mem.Allocator;
 const args = @import("args.zig");
 const Action = @import("ghostty.zig").Action;
+const Duration = @import("../config.zig").Config.Duration;
 pub const Entry = @import("ssh-cache/Entry.zig");
 pub const DiskCache = @import("ssh-cache/DiskCache.zig");
 
@@ -10,8 +11,7 @@ pub const Options = struct {
     clear: bool = false,
     add: ?[]const u8 = null,
     remove: ?[]const u8 = null,
-    host: ?[]const u8 = null,
+    prune: ?Duration = null,
-    @"expire-days": ?u32 = null,
 
     pub fn deinit(self: *Options) void {
         _ = self;
@@ -25,27 +25,36 @@ pub const Options = struct {
 
 /// Manage the SSH terminfo cache for automatic remote host setup.
 ///
-/// When SSH integration is enabled with `shell-integration-features = ssh-terminfo`,
+/// The `+ssh` action installs Ghostty's terminfo on remote hosts and records
-/// Ghostty automatically installs its terminfo on remote hosts. This command
+/// each success in this cache so it doesn't re-upload on later connections.
-/// manages the cache of successful installations to avoid redundant uploads.
+/// (`+ssh` runs automatically from the shell integration when
+/// `shell-integration-features` includes `ssh-terminfo`.) This command
+/// inspects and maintains that cache.
 ///
-/// The cache stores hostnames (or user@hostname combinations) along with timestamps.
+/// The cache stores destinations (a hostname or user@hostname) along with
-/// Entries older than the expiration period are automatically removed during cache
+/// timestamps.
-/// operations. By default, entries never expire.
 ///
-/// Only one of `--clear`, `--add`, `--remove`, or `--host` can be specified.
+/// A positional destination queries the cache: `user@hostname` shows that
-/// If multiple are specified, one of the actions will be executed but
+/// exact entry, while a bare `hostname` shows every cached entry for that
-/// it isn't guaranteed which one. This is entirely unsafe so you should split
+/// host regardless of user. With no destination and no action, the entire
-/// multiple actions into separate commands.
+/// cache is listed. A query that matches nothing exits 1.
+///
+/// At most one action (`--clear`, `--add`, `--remove`, or `--prune`) may be
+/// specified, and not together with a positional destination; combining them
+/// is an error.
+///
+/// `--prune` takes a duration with unit suffixes (`s`, `m`, `h`, `d`, `w`,
+/// `y`) and removes every entry older than it, e.g. `--prune=30d`,
+/// `--prune=6h`, `--prune=1y`.
 ///
 /// Examples:
-///   ghostty +ssh-cache                          # List all cached hosts
+///   ghostty +ssh-cache                           # List all cached destinations
-///   ghostty +ssh-cache --host=example.com       # Check if host is cached
+///   ghostty +ssh-cache user@example.com          # Show that destination
-///   ghostty +ssh-cache --add=example.com        # Manually add host to cache
+///   ghostty +ssh-cache example.com               # Show all users on that host
-///   ghostty +ssh-cache --add=user@example.com   # Add user@host combination
+///   ghostty +ssh-cache --add=user@example.com    # Manually add a destination
-///   ghostty +ssh-cache --remove=example.com     # Remove host from cache
+///   ghostty +ssh-cache --remove=user@example.com # Remove a destination
+///   ghostty +ssh-cache --prune=30d               # Remove entries older than 30 days
 ///   ghostty +ssh-cache --clear                   # Clear entire cache
-///   ghostty +ssh-cache --expire-days=30         # Set custom expiration period
 pub fn run(alloc_gpa: Allocator) !u8 {
     var arena = std.heap.ArenaAllocator.init(alloc_gpa);
     defer arena.deinit();
@@ -54,12 +63,6 @@ pub fn run(alloc_gpa: Allocator) !u8 {
     var opts: Options = .{};
     defer opts.deinit();
 
-    {
-        var iter = try args.argsIterator(alloc_gpa);
-        defer iter.deinit();
-        try args.parse(Options, alloc_gpa, &opts, &iter);
-    }
-
     var stdout_buffer: [1024]u8 = undefined;
     var stdout_file: std.fs.File = .stdout();
     var stdout_writer = stdout_file.writer(&stdout_buffer);
@@ -70,7 +73,66 @@ pub fn run(alloc_gpa: Allocator) !u8 {
     var stderr_writer = stderr_file.writer(&stderr_buffer);
     const stderr = &stderr_writer.interface;
 
-    const result = runInner(alloc, opts, stdout, stderr);
+    // The cache is queried by a positional destination (`user@host` or a
+    // bare `host`). `args.parse` rejects non-`--` tokens, so we lift the
+    // positional out here and parse only the remaining flags. `--host=X`
+    // is accepted as a deprecated spelling of the positional (it was the
+    // original shipped flag name).
+    var query: ?[]const u8 = null;
+    var flags: std.ArrayList([]const u8) = .empty;
+    {
+        var iter = try args.argsIterator(alloc_gpa);
+        defer iter.deinit();
+        while (iter.next()) |arg| {
+            const is_host_flag = std.mem.startsWith(u8, arg, "--host=");
+            if (is_host_flag) {
+                try stderr.print(
+                    "Warning: --host is deprecated; pass the destination " ++
+                        "directly, e.g. `ghostty +ssh-cache {s}`.\n",
+                    .{arg["--host=".len..]},
+                );
+            }
+            const dest: ?[]const u8 = if (is_host_flag)
+                arg["--host=".len..]
+            else if (!std.mem.startsWith(u8, arg, "-"))
+                arg
+            else
+                null;
+
+            if (dest) |d| {
+                if (query != null) {
+                    try stderr.print(
+                        "Error: only one destination may be specified.\n",
+                        .{},
+                    );
+                    stderr.flush() catch {};
+                    return 2;
+                }
+                query = try alloc.dupe(u8, d);
+            } else {
+                try flags.append(alloc, try alloc.dupe(u8, arg));
+            }
+        }
+    }
+
+    {
+        var iter = args.sliceIterator(flags.items);
+        args.parse(Options, alloc_gpa, &opts, &iter) catch |err| switch (err) {
+            error.InvalidField => {
+                try stderr.print("Error: unknown flag.\n", .{});
+                stderr.flush() catch {};
+                return 2;
+            },
+            error.InvalidValue, error.ValueRequired => {
+                try stderr.print("Error: invalid flag value.\n", .{});
+                stderr.flush() catch {};
+                return 2;
+            },
+            else => return err,
+        };
+    }
+
+    const result = runInner(alloc, opts, query, stdout, stderr);
 
     // Flushing *shouldn't* fail but...
     stdout.flush() catch {};
@@ -81,103 +143,126 @@ pub fn run(alloc_gpa: Allocator) !u8 {
 pub fn runInner(
     alloc: Allocator,
     opts: Options,
+    query: ?[]const u8,
     stdout: *std.Io.Writer,
     stderr: *std.Io.Writer,
 ) !u8 {
+    // At most one action may be specified, and a query (positional
+    // destination) is itself an action.
+    const action_count =
+        @as(usize, @intFromBool(opts.clear)) +
+        @intFromBool(opts.add != null) +
+        @intFromBool(opts.remove != null) +
+        @intFromBool(opts.prune != null) +
+        @intFromBool(query != null);
+    if (action_count > 1) {
+        try stderr.print(
+            "Error: only one of a destination, --clear, --add, --remove, " ++
+                "or --prune may be specified.\n",
+            .{},
+        );
+        return 2;
+    }
+
     // Setup our disk cache to the standard location
     const cache_path = try DiskCache.defaultPath(alloc, "ghostty");
     const cache: DiskCache = .{ .path = cache_path };
 
     if (opts.clear) {
         try cache.clear();
-        try stdout.print("Cache cleared.\n", .{});
         return 0;
     }
 
-    if (opts.add) |host| {
+    if (opts.add) |dest| {
-        const result = cache.add(alloc, host) catch |err| switch (err) {
+        cache.add(alloc, dest, std.time.timestamp()) catch |err| switch (err) {
-            DiskCache.Error.HostnameIsInvalid => {
+            error.InvalidCacheKey => {
-                try stderr.print("Error: Invalid hostname format '{s}'\n", .{host});
+                try stderr.print(
-                try stderr.print("Expected format: hostname or user@hostname\n", .{});
+                    "Error: Invalid destination '{s}' (expected hostname or user@hostname)\n",
-                return 1;
+                    .{dest},
-            },
+                );
-            DiskCache.Error.CacheIsLocked => {
+                return 2;
-                try stderr.print("Error: Cache is busy, try again\n", .{});
-                return 1;
             },
             else => {
                 try stderr.print(
                     "Error: Unable to add '{s}' to cache. Error: {}\n",
-                    .{ host, err },
+                    .{ dest, err },
                 );
                 return 1;
             },
         };
-
-        switch (result) {
-            .added => try stdout.print("Added '{s}' to cache.\n", .{host}),
-            .updated => try stdout.print("Updated '{s}' cache entry.\n", .{host}),
-        }
         return 0;
     }
 
-    if (opts.remove) |host| {
+    if (opts.remove) |dest| {
-        cache.remove(alloc, host) catch |err| switch (err) {
+        const removed = cache.remove(alloc, dest) catch |err| switch (err) {
-            DiskCache.Error.HostnameIsInvalid => {
+            error.InvalidCacheKey => {
-                try stderr.print("Error: Invalid hostname format '{s}'\n", .{host});
+                try stderr.print(
-                try stderr.print("Expected format: hostname or user@hostname\n", .{});
+                    "Error: Invalid destination '{s}' (expected hostname or user@hostname)\n",
-                return 1;
+                    .{dest},
-            },
+                );
-            DiskCache.Error.CacheIsLocked => {
+                return 2;
-                try stderr.print("Error: Cache is busy, try again\n", .{});
-                return 1;
             },
             else => {
                 try stderr.print(
                     "Error: Unable to remove '{s}' from cache. Error: {}\n",
-                    .{ host, err },
+                    .{ dest, err },
                 );
                 return 1;
             },
         };
-        try stdout.print("Removed '{s}' from cache.\n", .{host});
+        // Silence on success; a no-op removal is an error (exit 1).
+        if (!removed) {
+            try stderr.print("Error: '{s}' is not in the cache.\n", .{dest});
+            return 1;
+        }
         return 0;
     }
 
-    if (opts.host) |host| {
+    if (opts.prune) |max_age| {
-        const cached = cache.contains(alloc, host) catch |err| switch (err) {
+        const max_age_s = max_age.duration / std.time.ns_per_s;
-            error.HostnameIsInvalid => {
+        if (max_age_s == 0) {
-                try stderr.print("Error: Invalid hostname format '{s}'\n", .{host});
-                try stderr.print("Expected format: hostname or user@hostname\n", .{});
-                return 1;
-            },
-            else => {
             try stderr.print(
-                    "Error: Unable to check host '{s}' in cache. Error: {}\n",
+                "Error: --prune requires a duration of at least one second.\n",
-                    .{ host, err },
+                .{},
             );
+            return 2;
+        }
+        const pruned = cache.prune(alloc, max_age_s) catch |err| {
+            try stderr.print("Error: Unable to prune cache. Error: {}\n", .{err});
             return 1;
-            },
         };
-
+        try stdout.print("Pruned cache entries: {d}\n", .{pruned});
-        if (cached) {
-            try stdout.print(
-                "'{s}' has Ghostty terminfo installed.\n",
-                .{host},
-            );
         return 0;
-        } else {
-            try stdout.print(
-                "'{s}' does not have Ghostty terminfo installed.\n",
-                .{host},
-            );
-            return 1;
-        }
     }
 
-    // Default action: list all hosts
     var entries = try cache.list(alloc);
     defer DiskCache.deinitEntries(alloc, &entries);
+
+    // A positional query filters the listing: an exact `user@host` match,
+    // or every entry on a bare `host`.
+    if (query) |q| {
+        if (!DiskCache.isValidCacheKey(q)) {
+            try stderr.print(
+                "Error: Invalid destination '{s}' (expected hostname or user@hostname)\n",
+                .{q},
+            );
+            return 2;
+        }
+
+        var matches: std.StringHashMap(Entry) = .init(alloc);
+        defer matches.deinit();
+        var iter = entries.iterator();
+        while (iter.next()) |kv| {
+            const key = kv.key_ptr.*;
+            if (matchesQuery(key, q)) try matches.put(key, kv.value_ptr.*);
+        }
+
+        if (matches.count() == 0) return 1;
+        try listEntries(alloc, &matches, stdout);
+        return 0;
+    }
+
+    // List all destinations by default.
     try listEntries(alloc, &entries, stdout);
     return 0;
 }
@@ -187,10 +272,7 @@ fn listEntries(
     entries: *const std.StringHashMap(Entry),
     writer: *std.Io.Writer,
 ) !void {
-    if (entries.count() == 0) {
+    if (entries.count() == 0) return;
-        try writer.print("No hosts in cache.\n", .{});
-        return;
-    }
 
     // Sort entries by hostname for consistent output
     var items: std.ArrayList(Entry) = .empty;
@@ -207,22 +289,200 @@ fn listEntries(
         }
     }.lessThan);
 
-    try writer.print("Cached hosts ({d}):\n", .{items.items.len});
+    // Align the timestamp column by padding destinations to the widest.
-    const now = std.time.timestamp();
+    var widest: usize = 0;
-
     for (items.items) |entry| {
-        const age_days = @divTrunc(now - entry.timestamp, std.time.s_per_day);
+        widest = @max(widest, entry.hostname.len);
-        if (age_days == 0) {
-            try writer.print("  {s} (today)\n", .{entry.hostname});
-        } else if (age_days == 1) {
-            try writer.print("  {s} (yesterday)\n", .{entry.hostname});
-        } else {
-            try writer.print("  {s} ({d} days ago)\n", .{ entry.hostname, age_days });
     }
+
+    const now = std.time.timestamp();
+    for (items.items) |entry| {
+        try writer.print("{s}", .{entry.hostname});
+        try writer.splatByteAll(' ', widest - entry.hostname.len + 2);
+
+        var iso_buf: [20]u8 = undefined;
+        var age_buf: [32]u8 = undefined;
+        try writer.print("{s} ({s})\n", .{
+            formatTimestamp(&iso_buf, entry.timestamp),
+            relativeAge(&age_buf, now, entry.timestamp),
+        });
     }
 }
 
+/// Whether a cache `key` matches a positional `query`. A `user@host` query
+/// (containing `@`) matches one exact key; a bare `host` query matches every
+/// key on that host regardless of user, comparing against the key's host
+/// component (everything after its first `@`, or the whole key if userless).
+fn matchesQuery(key: []const u8, query: []const u8) bool {
+    if (std.mem.indexOfScalar(u8, query, '@') != null) {
+        return std.mem.eql(u8, key, query);
+    }
+
+    const at = std.mem.indexOfScalar(u8, key, '@');
+    const host = if (at) |i| key[i + 1 ..] else key;
+    return std.mem.eql(u8, host, query);
+}
+
+test matchesQuery {
+    const testing = std.testing;
+
+    // Exact user@host: only the identical key.
+    try testing.expect(matchesQuery("user@example.com", "user@example.com"));
+    try testing.expect(!matchesQuery("root@example.com", "user@example.com"));
+    try testing.expect(!matchesQuery("example.com", "user@example.com"));
+
+    // Bare host: every key on that host, plus a keyless entry for it.
+    try testing.expect(matchesQuery("user@example.com", "example.com"));
+    try testing.expect(matchesQuery("root@example.com", "example.com"));
+    try testing.expect(matchesQuery("example.com", "example.com"));
+    try testing.expect(!matchesQuery("user@other.com", "example.com"));
+}
+
+/// Format a Unix timestamp as an ISO-8601 UTC string
+/// (`YYYY-MM-DDTHH:MM:SSZ`) into `buf`, which must be at least 20 bytes.
+/// Out-of-range input is clamped so this can't crash on a garbage cache line.
+fn formatTimestamp(buf: []u8, timestamp: i64) []const u8 {
+    // Clamp to [epoch, last second of 9999-12-31Z]: `std.time.epoch`
+    // accumulates the year in a `u16` (panics beyond that), and the buffer
+    // only fits a 4-digit year.
+    const secs: u64 = @intCast(std.math.clamp(timestamp, 0, 253402300799));
+
+    const epoch = std.time.epoch;
+    const epoch_secs: epoch.EpochSeconds = .{ .secs = secs };
+    const day = epoch_secs.getEpochDay();
+    const year_day = day.calculateYearDay();
+    const month_day = year_day.calculateMonthDay();
+    const ds = epoch_secs.getDaySeconds();
+    return std.fmt.bufPrint(buf, "{d:0>4}-{d:0>2}-{d:0>2}T{d:0>2}:{d:0>2}:{d:0>2}Z", .{
+        year_day.year,
+        month_day.month.numeric(),
+        month_day.day_index + 1,
+        ds.getHoursIntoDay(),
+        ds.getMinutesIntoHour(),
+        ds.getSecondsIntoMinute(),
+    }) catch unreachable;
+}
+
+test formatTimestamp {
+    const testing = std.testing;
+    var buf: [20]u8 = undefined;
+
+    try testing.expectEqualStrings(
+        "2026-05-05T22:49:33Z",
+        formatTimestamp(&buf, 1778021373),
+    );
+
+    // Epoch.
+    try testing.expectEqualStrings(
+        "1970-01-01T00:00:00Z",
+        formatTimestamp(&buf, 0),
+    );
+
+    // Out-of-range inputs clamp instead of overflowing the [20]u8 /
+    // panicking inside std: negatives floor at the epoch, huge values cap
+    // at the last second of year 9999.
+    try testing.expectEqualStrings(
+        "1970-01-01T00:00:00Z",
+        formatTimestamp(&buf, -5),
+    );
+    try testing.expectEqualStrings(
+        "9999-12-31T23:59:59Z",
+        formatTimestamp(&buf, std.math.maxInt(i64)),
+    );
+}
+
+/// Format the age of `timestamp` (relative to `now`, both Unix seconds)
+/// as a coarse relative time into `buf`, e.g. "2w ago". Uses `Duration`'s
+/// unit vocabulary but keeps only the single largest unit for scannability.
+/// A non-positive age (timestamp at or after `now`) is "now".
+fn relativeAge(buf: []u8, now: i64, timestamp: i64) []const u8 {
+    // Saturating so a garbage timestamp can't overflow; clamp at 0 so a
+    // future timestamp becomes a zero age rather than going negative.
+    const age: u64 = @intCast(@max(0, now -| timestamp));
+    if (age == 0) return "now";
+
+    // Round down to the largest unit that fits, so Duration.format emits
+    // only that unit (e.g. 19d -> 2w, 90m -> 1h).
+    const units = [_]u64{
+        365 * std.time.s_per_day, // y
+        std.time.s_per_week, // w
+        std.time.s_per_day, // d
+        std.time.s_per_hour, // h
+        std.time.s_per_min, // m
+        1, // s
+    };
+    const unit = for (units) |u| {
+        if (age >= u) break u;
+    } else 1;
+
+    // Cap the age so `age * ns_per_s` can't overflow u64 (a garbage, e.g.
+    // hugely negative, timestamp otherwise yields an age near i64-max).
+    const max_age = std.math.maxInt(u64) / std.time.ns_per_s;
+    const rounded = @min(age, max_age) / unit * unit;
+    const d: Duration = .{ .duration = rounded * std.time.ns_per_s };
+    return std.fmt.bufPrint(buf, "{f} ago", .{d}) catch unreachable;
+}
+
+test relativeAge {
+    const testing = std.testing;
+    var buf: [32]u8 = undefined;
+    const now: i64 = 2_000_000_000; // fixed reference
+    const min = std.time.s_per_min;
+    const hour = std.time.s_per_hour;
+    const day = std.time.s_per_day;
+
+    // Out-of-range timestamps don't crash: a huge future one saturates to
+    // a non-positive age ("now"); a negative one is a large but real age.
+    try testing.expectEqualStrings("now", relativeAge(&buf, now, std.math.maxInt(i64)));
+    try testing.expectEqualStrings("63y ago", relativeAge(&buf, now, -100));
+
+    // A huge age (garbage timestamp) saturates the ns conversion instead of
+    // overflowing; it must not crash and must fit the buffer.
+    try testing.expect(std.mem.endsWith(u8, relativeAge(&buf, std.math.maxInt(i64), 0), " ago"));
+
+    // Future timestamp (clock skew) and same-instant read "now".
+    try testing.expectEqualStrings("now", relativeAge(&buf, now, now + 100));
+    try testing.expectEqualStrings("now", relativeAge(&buf, now, now));
+
+    // Only the single largest unit is kept (smaller units rounded away).
+    try testing.expectEqualStrings("30s ago", relativeAge(&buf, now, now - 30));
+    try testing.expectEqualStrings("1m ago", relativeAge(&buf, now, now - min));
+    try testing.expectEqualStrings("1m ago", relativeAge(&buf, now, now - 90)); // 90s -> 1m
+    try testing.expectEqualStrings("1h ago", relativeAge(&buf, now, now - hour));
+    try testing.expectEqualStrings("1h ago", relativeAge(&buf, now, now - (hour + 30 * min))); // 1h30m -> 1h
+    try testing.expectEqualStrings("1d ago", relativeAge(&buf, now, now - day));
+    try testing.expectEqualStrings("2w ago", relativeAge(&buf, now, now - 19 * day)); // 19d -> 2w
+}
+
 test {
     _ = DiskCache;
     _ = Entry;
 }
+
+test "runInner rejects multiple actions" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    var stdout: std.Io.Writer.Allocating = .init(alloc);
+    defer stdout.deinit();
+    var stderr: std.Io.Writer.Allocating = .init(alloc);
+    defer stderr.deinit();
+
+    // The check runs before any cache access, so it never touches disk.
+    const code = try runInner(alloc, .{
+        .add = "example.com",
+        .remove = "other.com",
+    }, null, &stdout.writer, &stderr.writer);
+
+    try testing.expectEqual(@as(u8, 2), code);
+    try testing.expectEqualStrings("", stdout.written());
+    try testing.expect(std.mem.indexOf(u8, stderr.written(), "only one") != null);
+
+    // A positional query is itself an action: query + a flag conflicts.
+    stderr.clearRetainingCapacity();
+    const code2 = try runInner(alloc, .{
+        .clear = true,
+    }, "example.com", &stdout.writer, &stderr.writer);
+    try testing.expectEqual(@as(u8, 2), code2);
+    try testing.expect(std.mem.indexOf(u8, stderr.written(), "only one") != null);
+}