split hivectl main.rs into per-domain modules (#2509)

hivectl/src/choom.rs

@@ -0,0 +1,74 @@
+//! `hivectl choom <agent>` — drop into an interactive Claude session inside
+//! an agent container by exec-ing `machinectl shell` running claude as the
+//! agent user, mirroring the harness's per-turn claude invocation.
+
+#[cfg(unix)]
+use std::os::unix::process::CommandExt as _;
+
+use anyhow::{Result, bail};
+
+use crate::util::agent_exists;
+
+/// Drop into an interactive Claude session in the agent container.
+///
+/// Execs `machinectl shell <name>@h-<name>` running claude as the agent
+/// user from its state dir, reproducing the harness's per-turn claude
+/// invocation (flags, session selection, why it never collides with the
+/// live harness session). See `docs/tools/hivectl.md` (Choom) for the
+/// full rationale. Inherits the caller's PTY; requires root + a running
+/// container.
+pub(crate) fn choom(name: &str, resume_session: Option<&str>) -> Result<()> {
+    if !agent_exists(name)? {
+        bail!(
+            "no such agent: '{name}' (no state dir under {}/)",
+            hive_host_sock::AGENTS_ROOT
+        );
+    }
+    let container = hive_host_sock::container_name(name);
+    // Enter as the agent's unix user (== agent name) so claude reads the
+    // right `$HOME/.claude`.
+    let target = format!("{name}@{container}");
+    let claude = "/run/current-system/sw/bin/claude";
+    // Bind-mounted state dir; matches `hive-agent::paths::state_dir()`.
+    let state_dir = format!("/agents/{name}/state");
+    // Per-turn config the harness writes; matches `paths::config_dir()`.
+    let cfg = "/run/hive-config";
+    // `--resume <value>` passes through as `claude --resume <value>` —
+    // the rejoin-by-id surface. (claude's `--continue` is a bare flag
+    // that resumes the cwd's latest session — the harness's — and would
+    // consume a trailing value as the first PROMPT; choom never uses
+    // it.) The value is single-quoted into the shell script, so reject
+    // an embedded single quote (the only char that breaks
+    // single-quoting) to rule out injection — session ids never
+    // contain one.
+    let session_arg = match resume_session {
+        Some(val) => {
+            if val.contains('\'') {
+                bail!("invalid --resume value '{val}': must not contain a single quote");
+            }
+            format!("set -- --resume '{val}';")
+        }
+        None => "set --;".to_string(),
+    };
+    // Build claude's argv as the harness does, each flag included only
+    // when its file is present so a half-up container degrades to a bare
+    // session. `name` is `[a-z0-9._-]` so there's nothing to quote.
+    let inner = format!(
+        "cd {state_dir} || exit 1; {session_arg} \
+         [ -f {cfg}/claude-settings.json ] && set -- \"$@\" --settings {cfg}/claude-settings.json; \
+         [ -f {cfg}/claude-mcp-config.json ] && set -- \"$@\" --mcp-config {cfg}/claude-mcp-config.json; \
+         [ -f {cfg}/claude-system-prompt.md ] && set -- \"$@\" --system-prompt-file {cfg}/claude-system-prompt.md; \
+         exec {claude} \"$@\""
+    );
+    let mut cmd = std::process::Command::new("machinectl");
+    cmd.arg("shell")
+        .arg(&target)
+        .arg("/bin/sh")
+        .arg("-lc")
+        .arg(&inner);
+    // exec() replaces the current process — we inherit stdin/stdout/stderr
+    // (the caller's PTY) so the Claude session is fully interactive.
+    // This call only returns on error.
+    let err = cmd.exec();
+    Err(anyhow::anyhow!("exec machinectl: {err}"))
+}