fix(config): marker set/clear no-op outside a git repository

docs/src/content/docs/claude-code.md

@@ -117,8 +117,8 @@ Activity tracking is not plugin-specific. The plugins above only call `wt` on th
 
 Three things to get right:
 
-- **Run the command inside the worktree.** Each one resolves the branch from its working directory, so a hook that runs elsewhere marks the wrong branch, and one that runs outside a repository fails. Where the host pins the working directory elsewhere, pass the global `-C <worktree>`, which moves both the repository lookup and the branch resolution. `--branch <branch>` names the branch on its own, but the repository lookup still comes from the working directory — that, not a missing worktree argument, is why a caller pinned outside the repository needs `-C`. Elsewhere, a command that names a branch ([`wt switch`](/switch/), [`wt remove`](/remove/), `wt step diff --branch`) already names the worktree it acts on, and `-C` is for reaching a different repository rather than a different worktree.
-- **Don't let a failed marker call fail the session.** Both `set` and `clear` exit non-zero outside a repository, and hosts differ on what a non-zero hook does. Append `|| true` (or the host's equivalent) to every call unless you want that surfaced.
+- **Run the command inside the worktree.** Each one resolves the branch from its working directory, so a hook that runs elsewhere marks the wrong branch, and one that runs outside a repository silently does nothing. Where the host pins the working directory elsewhere, pass the global `-C <worktree>`, which moves both the repository lookup and the branch resolution. `--branch <branch>` names the branch on its own, but the repository lookup still comes from the working directory — that, not a missing worktree argument, is why a caller pinned outside the repository needs `-C`. Elsewhere, a command that names a branch ([`wt switch`](/switch/), [`wt remove`](/remove/), `wt step diff --branch`) already names the worktree it acts on, and `-C` is for reaching a different repository rather than a different worktree.
+- **Don't let a failed marker call fail the session.** Outside a repository both `set` and `clear` do nothing and exit 0, but an invalid `--branch` or a failed git config write still exits non-zero, and hosts differ on what a non-zero hook does. Append `|| true` (or the host's equivalent) to every call unless you want that surfaced.
 - **Clear on exit.** A marker set on session start persists until something clears it, so pair every set with a clear on the host's session-end event — and expect the same stale marker as above if the process is killed first.
 
 ## Worktree isolation (Claude Code only)

plugins/worktrunk/skills/worktrunk/reference/claude-code.md

@@ -109,8 +109,8 @@ Activity tracking is not plugin-specific. The plugins above only call `wt` on th
 
 Three things to get right:
 
-- **Run the command inside the worktree.** Each one resolves the branch from its working directory, so a hook that runs elsewhere marks the wrong branch, and one that runs outside a repository fails. Where the host pins the working directory elsewhere, pass the global `-C <worktree>`, which moves both the repository lookup and the branch resolution. `--branch <branch>` names the branch on its own, but the repository lookup still comes from the working directory — that, not a missing worktree argument, is why a caller pinned outside the repository needs `-C`. Elsewhere, a command that names a branch ([`wt switch`](https://worktrunk.dev/switch/), [`wt remove`](https://worktrunk.dev/remove/), `wt step diff --branch`) already names the worktree it acts on, and `-C` is for reaching a different repository rather than a different worktree.
-- **Don't let a failed marker call fail the session.** Both `set` and `clear` exit non-zero outside a repository, and hosts differ on what a non-zero hook does. Append `|| true` (or the host's equivalent) to every call unless you want that surfaced.
+- **Run the command inside the worktree.** Each one resolves the branch from its working directory, so a hook that runs elsewhere marks the wrong branch, and one that runs outside a repository silently does nothing. Where the host pins the working directory elsewhere, pass the global `-C <worktree>`, which moves both the repository lookup and the branch resolution. `--branch <branch>` names the branch on its own, but the repository lookup still comes from the working directory — that, not a missing worktree argument, is why a caller pinned outside the repository needs `-C`. Elsewhere, a command that names a branch ([`wt switch`](https://worktrunk.dev/switch/), [`wt remove`](https://worktrunk.dev/remove/), `wt step diff --branch`) already names the worktree it acts on, and `-C` is for reaching a different repository rather than a different worktree.
+- **Don't let a failed marker call fail the session.** Outside a repository both `set` and `clear` do nothing and exit 0, but an invalid `--branch` or a failed git config write still exits non-zero, and hosts differ on what a non-zero hook does. Append `|| true` (or the host's equivalent) to every call unless you want that surfaced.
 - **Clear on exit.** A marker set on session start persists until something clears it, so pair every set with a clear on the host's session-end event — and expect the same stale marker as above if the process is killed first.
 
 ## Worktree isolation (Claude Code only)

src/commands/config/state.rs

@@ -76,7 +76,7 @@ use crate::commands::picker::preview_cache;
 use anyhow::Context;
 use color_print::cformat;
 use path_slash::PathExt as _;
-use worktrunk::git::{BranchRef, Repository, resolve_input_path, sha_cache};
+use worktrunk::git::{BranchRef, CommandError, Repository, resolve_input_path, sha_cache};
 use worktrunk::path::format_path_for_display;
 use worktrunk::styling::{
     eprintln, format_heading, format_with_gutter, hint_message, info_message, println,
@@ -834,9 +834,39 @@ pub fn handle_state_get(
     Ok(())
 }
 
+/// True when `err` is `Repository::current()` failing with the exit 128 that
+/// `git rev-parse --git-common-dir` returns when the discovery path has no
+/// usable git repository. That covers the missing-repo case the marker hooks
+/// hit, and equally an unreadable or corrupt `.git`, which git reports the
+/// same way and which no-ops just as harmlessly for a marker. Any other exit
+/// code still propagates, so the #3921 fallback stays off unrelated failures.
+///
+/// The exit code is the whole check on purpose. git translates
+/// `not a git repository`, and the translation ships in the distro package,
+/// so matching that text would leave every non-English user on the old
+/// behavior with nothing in the suite able to catch it.
+fn is_missing_repository_error(err: &anyhow::Error) -> bool {
+    CommandError::find_in(err).is_some_and(|cmd_err| cmd_err.exit_code == Some(128))
+}
+
 /// Handle the state set command
 pub fn handle_state_set(key: &str, value: String, branch: Option<String>) -> anyhow::Result<()> {
-    let repo = Repository::current()?;
+    let repo = match Repository::current() {
+        Ok(repo) => repo,
+        Err(err) if key == "marker" && is_missing_repository_error(&err) => {
+            // The Claude Code / Codex / Gemini marker hooks call `marker set`
+            // unconditionally on every turn (`UserPromptSubmit`, `Stop`, …),
+            // regardless of whether the session's directory is inside a git
+            // repository. Before this, a session started outside a repo made
+            // every one of those calls print `git rev-parse --git-common-dir
+            // failed (exit 128)` to stderr and exit 1 — silently discarded by
+            // the hook's own `|| true`, but still a spurious failure on every
+            // turn. Treat "no repository here" as the no-op it already
+            // behaves like from the hook's perspective (#3921).
+            return Ok(());
+        }
+        Err(err) => return Err(err),
+    };
 
     match key {
         "default-branch" => {
@@ -893,7 +923,15 @@ pub fn handle_state_set(key: &str, value: String, branch: Option<String>) -> any
 
 /// Handle the state clear command
 pub fn handle_state_clear(key: &str, branch: Option<String>, all: bool) -> anyhow::Result<()> {
-    let repo = Repository::current()?;
+    let repo = match Repository::current() {
+        Ok(repo) => repo,
+        Err(err) if key == "marker" && is_missing_repository_error(&err) => {
+            // `SessionEnd` fires the same unconditional `marker clear` call —
+            // see the matching comment in `handle_state_set`.
+            return Ok(());
+        }
+        Err(err) => return Err(err),
+    };
 
     match key {
         "default-branch" => {

tests/integration_tests/config_state.rs

@@ -1094,6 +1094,78 @@ fn test_state_clear_marker_all_empty(repo: TestRepo) {
     assert_snapshot!(String::from_utf8_lossy(&output.stderr), @"○ No markers to clear");
 }
 
+/// `marker set`/`marker clear` run unconditionally from the Claude Code,
+/// Codex, and Gemini plugin hooks (`UserPromptSubmit`, `Stop`, `SessionEnd`,
+/// …), whether or not the session's directory is inside a git repository.
+/// Outside a repository, both must no-op silently — exit 0, nothing on
+/// stdout or stderr — rather than the pre-fix behavior of printing
+/// `git rev-parse --git-common-dir failed (exit 128)` and exiting 1, a
+/// failure the hooks' own `|| true` already discarded (#3921).
+#[rstest]
+fn test_state_set_marker_outside_repo_is_noop() {
+    let mut cmd = wt_command();
+    cmd.args(["config", "state", "marker", "set", "🤖"]);
+    let output = cmd.output().unwrap();
+
+    assert!(
+        output.status.success(),
+        "stderr: {}",
+        String::from_utf8_lossy(&output.stderr)
+    );
+    assert_eq!(String::from_utf8_lossy(&output.stdout), "");
+    assert_eq!(String::from_utf8_lossy(&output.stderr), "");
+}
+
+#[rstest]
+fn test_state_clear_marker_outside_repo_is_noop() {
+    let mut cmd = wt_command();
+    cmd.args(["config", "state", "marker", "clear"]);
+    let output = cmd.output().unwrap();
+
+    assert!(
+        output.status.success(),
+        "stderr: {}",
+        String::from_utf8_lossy(&output.stderr)
+    );
+    assert_eq!(String::from_utf8_lossy(&output.stdout), "");
+    assert_eq!(String::from_utf8_lossy(&output.stderr), "");
+}
+
+/// The no-op fallback is scoped to `marker` — a state key without a git
+/// hook depending on it, run outside a repository, must keep failing the
+/// way every `wt` command does. Guards against widening the `#3921` fix
+/// beyond the one command the hooks actually call unconditionally.
+#[rstest]
+fn test_state_set_default_branch_outside_repo_still_fails() {
+    let mut cmd = wt_command();
+    cmd.args(["config", "state", "default-branch", "set", "main"]);
+    let output = cmd.output().unwrap();
+
+    assert!(!output.status.success());
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("git rev-parse --git-common-dir failed"),
+        "stderr: {stderr}"
+    );
+}
+
+/// Same guard as `test_state_set_default_branch_outside_repo_still_fails`,
+/// for the `clear` side — `handle_state_clear` has its own `Repository::current()`
+/// match with its own fallback arm.
+#[rstest]
+fn test_state_clear_default_branch_outside_repo_still_fails() {
+    let mut cmd = wt_command();
+    cmd.args(["config", "state", "default-branch", "clear"]);
+    let output = cmd.output().unwrap();
+
+    assert!(!output.status.success());
+    let stderr = String::from_utf8_lossy(&output.stderr);
+    assert!(
+        stderr.contains("git rev-parse --git-common-dir failed"),
+        "stderr: {stderr}"
+    );
+}
+
 // ============================================================================
 // logs
 // ============================================================================