Support Grok Build CLI as a provider

README.md

@@ -12,7 +12,7 @@
 
 Reach for it whenever you don't want to explain the whole job again: an agent hits its usage limit, you switch tools mid-task, you pick up older work, or you want a clean record of what happened.
 
-Works with **Amp**, **Claude Code**, **Codex**, **Copilot CLI**, **Cursor**, **Cline**, **Kimi**, **Antigravity**, **OpenCode**, **Pi Agent**, **ZCode**, and **DeepSeek Harness**.
+Works with **Amp**, **Claude Code**, **Codex**, **Copilot CLI**, **Cursor**, **Cline**, **Kimi**, **Antigravity**, **OpenCode**, **Pi Agent**, **ZCode**, **Grok Build**, and **DeepSeek Harness**.
 
 <div align="center">
 
@@ -56,7 +56,7 @@ herdr plugin install wilbeibi/herdr-catchup
 
 ## Usage
 
-Agents: amp · `claude` · `codex` · `copilot` · `cursor` · `cline` · `kimi` · `agy` (Antigravity) · `opencode` · `pi-agent` · `zcode` · `deepseek` (dsh)
+Agents: amp · `claude` · `codex` · `copilot` · `cursor` · `cline` · `kimi` · `agy` (Antigravity) · `opencode` · `pi-agent` · `zcode` · `deepseek` (dsh) · `grok`
 
 Omit `<agent>` and catchup uses whichever agent has the newest session in this directory. Inside a live session, that's usually the session you're in.
 

SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: catchup
-description: Recovers the conversation and failed tool calls of a previous Codex, Amp, Claude Code, Antigravity, Cline, Copilot CLI, Cursor, DeepSeek Harness, Kimi, OpenCode, Pi Agent, or ZCode session. Use when the user says "catch up", "what did the last session do", "get me up to speed", "I switched agents", asks to recover/summarize a previous session before continuing, or asks to diagnose or report a catchup failure. Do NOT use for the current conversation, git history, or any non-agent log.
+description: Recovers the conversation and failed tool calls of a previous Codex, Amp, Claude Code, Antigravity, Cline, Copilot CLI, Cursor, DeepSeek Harness, Grok Build, Kimi, OpenCode, Pi Agent, or ZCode session. Use when the user says "catch up", "what did the last session do", "get me up to speed", "I switched agents", asks to recover/summarize a previous session before continuing, or asks to diagnose or report a catchup failure. Do NOT use for the current conversation, git history, or any non-agent log.
 ---
 
 # catchup
@@ -27,7 +27,7 @@ catchup fork <agent>               # native resume, full state
 catchup fork <agent> --into <other>  # seed a different agent with the transcript
 ```
 
-Agents: `amp`, `codex`, `claude`, `agy` (Antigravity), `cline`, `copilot`, `cursor`, `deepseek` (dsh), `kimi`, `opencode`, `pi-agent`, `zcode`.
+Agents: `amp`, `codex`, `claude`, `agy` (Antigravity), `cline`, `copilot`, `cursor`, `deepseek` (dsh), `grok`, `kimi`, `opencode`, `pi-agent`, `zcode`.
 
 ## Before loading a transcript
 

internal/cli/agentlist_test.go

@@ -127,6 +127,7 @@ func TestProseNamesEveryAgent(t *testing.T) {
 		session.ProviderCopilot:  "Copilot CLI",
 		session.ProviderCursor:   "Cursor",
 		session.ProviderDeepSeek: "DeepSeek Harness",
+		session.ProviderGrok:     "Grok Build",
 		session.ProviderKimi:     "Kimi",
 		session.ProviderOpenCode: "OpenCode",
 		session.ProviderPiAgent:  "Pi Agent",

internal/cli/cli.go

@@ -30,6 +30,7 @@ import (
 	"github.com/wilbeibi/catchup/internal/copilot"
 	"github.com/wilbeibi/catchup/internal/cursor"
 	"github.com/wilbeibi/catchup/internal/deepseek"
+	"github.com/wilbeibi/catchup/internal/grok"
 	"github.com/wilbeibi/catchup/internal/kimi"
 	"github.com/wilbeibi/catchup/internal/opencode"
 	"github.com/wilbeibi/catchup/internal/piagent"
@@ -44,7 +45,7 @@ const helpText = `Usage: catchup [agent[/<rank>]] [flags]        read a past ses
        catchup install-skill [agent]
 
 Agents: amp, codex, claude, agy (Antigravity), cline, copilot, cursor, deepseek (dsh),
-kimi, opencode, pi-agent, zcode
+grok, kimi, opencode, pi-agent, zcode
 Omit the agent to use whichever has the newest session here. Bare ` + "`catchup`" + `
 prints that session in full, as Markdown. The flags refine three things:
 which session, how much of it, and as what.
@@ -385,6 +386,8 @@ func selectProvider(name string) (session.Provider, error) {
 		return cursor.New(), nil
 	case session.ProviderDeepSeek:
 		return deepseek.New(), nil
+	case session.ProviderGrok:
+		return grok.New(), nil
 	case session.ProviderKimi:
 		return kimi.New(), nil
 	case session.ProviderOpenCode:
@@ -935,6 +938,10 @@ func intoCommand(target, prompt, model string) (string, []string, error) {
 		// -i starts interactive and auto-executes the prompt; a bare -p is
 		// non-interactive and exits when the answer lands.
 		return "copilot", append(modelArgs("--model", model), "-i", prompt), nil
+	case session.ProviderGrok:
+		// The TUI takes its opening prompt as a positional argument (a bare -p
+		// runs headless and exits); options must precede it.
+		return "grok", append(modelArgs("-m", model), prompt), nil
 	case session.ProviderKimi:
 		// Kimi rejects positional arguments and its -p flag is
 		// non-interactive print mode, so there is no way to start an
@@ -1035,6 +1042,13 @@ func forkCommand(src session.Source, model string) (string, []string, error) {
 		// Copilot has no fork; --resume is its native resume, and it takes
 		// the id inline (a bare --resume opens the session picker).
 		return "copilot", append([]string{"--resume=" + src.Ref.SessionID}, modelArgs("--model", model)...), nil
+	case session.ProviderGrok:
+		if src.Ref.SessionID == "" {
+			return "", nil, fmt.Errorf("fork grok: missing session id")
+		}
+		// --fork-session branches into a new id instead of appending to the
+		// original, which is what catchup's native fork means.
+		return "grok", append([]string{"--resume", src.Ref.SessionID, "--fork-session"}, modelArgs("-m", model)...), nil
 	case session.ProviderCursor:
 		if src.Ref.SessionID == "" {
 			return "", nil, fmt.Errorf("fork cursor: missing session id")

internal/cli/cli_test.go

@@ -146,6 +146,43 @@ func piAgentRoot(t *testing.T) session.Roots {
 	return session.Roots{PiAgent: root}
 }
 
+// grokRoot writes one Grok session under a percent-encoded cwd group and
+// returns a Roots pointing at it. summary.json is the index entry; the
+// transcript is chat_history.jsonl.
+func grokRoot(t *testing.T) session.Roots {
+	t.Helper()
+	root := t.TempDir()
+	dir := filepath.Join(root, "sessions", "%2Fhome%2Fu%2Fsrc%2Fproj", "gr-1")
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	summary := `{"info":{"id":"gr-1","cwd":"/home/u/src/proj"},"generated_title":"grok session","last_active_at":"2026-07-18T15:20:00Z"}`
+	chat, err := os.ReadFile("../grok/testdata/chat_history.jsonl")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "summary.json"), []byte(summary), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "chat_history.jsonl"), []byte(chat), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	return session.Roots{Grok: root}
+}
+
+func TestRunReadsGrokSession(t *testing.T) {
+	roots := grokRoot(t)
+	out := run(t, roots, "grok", "--id", "gr-1", "--since-compact")
+	for _, want := range []string{"agent: grok", "session: gr-1", "title: grok session", "support grok", "the compaction summary", "I will read the log."} {
+		if !strings.Contains(out, want) {
+			t.Errorf("grok read missing %q:\n%s", want, out)
+		}
+	}
+	if strings.Contains(out, "injected context") {
+		t.Error("--since-compact kept an obsolete compaction marker")
+	}
+}
+
 func runWithCwd(t *testing.T, roots session.Roots, cwd string, args ...string) string {
 	t.Helper()
 	var out, errOut bytes.Buffer
@@ -732,6 +769,8 @@ func TestForkCommand(t *testing.T) {
 		// which would swallow a separated id as an unrelated argument.
 		{"copilot", session.Source{Ref: session.Ref{Provider: session.ProviderCopilot, SessionID: "gh1"}}, "", "copilot --resume=gh1"},
 		{"copilot with model", session.Source{Ref: session.Ref{Provider: session.ProviderCopilot, SessionID: "gh1"}}, "gpt-5.4", "copilot --resume=gh1 --model gpt-5.4"},
+		{"grok", session.Source{Ref: session.Ref{Provider: session.ProviderGrok, SessionID: "gr1"}}, "", "grok --resume gr1 --fork-session"},
+		{"grok with model", session.Source{Ref: session.Ref{Provider: session.ProviderGrok, SessionID: "gr1"}}, "grok-4.7", "grok --resume gr1 --fork-session -m grok-4.7"},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -811,9 +850,10 @@ func runBoth(t *testing.T, roots session.Roots, cwd string, args ...string) (str
 func TestRunListAcrossAgents(t *testing.T) {
 	roots := codexRoot(t)
 	roots.Claude = claudeRoot(t).Claude
+	roots.Grok = grokRoot(t).Grok
 
 	out, _ := runBoth(t, roots, "", "--list")
-	for _, want := range []string{"codex/1", "claude/1", "claude/2"} {
+	for _, want := range []string{"codex/1", "claude/1", "claude/2", "grok/1"} {
 		if !strings.Contains(out, want) {
 			t.Errorf("cross-agent listing missing %q:\n%s", want, out)
 		}
@@ -1004,6 +1044,7 @@ func TestIntoCommandModelPlacement(t *testing.T) {
 		{session.ProviderAgy, "--model M -i PROMPT"},
 		{session.ProviderOpenCode, "--model M --prompt PROMPT"},
 		{session.ProviderCopilot, "--model M -i PROMPT"},
+		{session.ProviderGrok, "-m M PROMPT"},
 	}
 	for _, tt := range tests {
 		t.Run(tt.target, func(t *testing.T) {