feat(#2067): choom takes optional session id to resume, else blank session

docs/tools/hivectl-cli.md

@@ -379,13 +379,14 @@ Generate the federation peer-config block for THIS hive — the nix a peer opera
 
 Open an interactive Claude session inside an agent container.
 
-Execs `machinectl shell <name>@h-<name>` running claude as the agent user from its state dir, with the same settings / MCP config / system prompt the harness uses. Each launch starts a fresh, named ("choom") session so it never collides with the harness's live session in the same project dir. Requires root + a running container.
+Execs `machinectl shell <name>@h-<name>` running claude as the agent user from its state dir, with the same settings / MCP config / system prompt the harness uses. Without a session id you get a fresh blank session each launch; pass one to resume an earlier choom session (`--resume <id>`). Either way it never collides with the harness's live session — the harness pins its own session id via `--resume`, so a blank choom session is invisible to it. Requires root + a running container.
 
-**Usage:** `hivectl choom <NAME>`
+**Usage:** `hivectl choom <NAME> [SESSION]`
 
 ###### **Arguments:**
 
 * `<NAME>` — Agent name (e.g. `damocles`, `iris`)
+* `<SESSION>` — Optional session id to resume (`claude --resume <id>`). Omit for a fresh blank session
 
 
 

docs/tools/hivectl.md

@@ -127,13 +127,16 @@ running claude from the agent's state dir. Requires root (same as all
 `machinectl shell` operations).
 
 ```bash
-hivectl choom iris                # fresh Claude session named "choom" in iris's container
+hivectl choom iris                # fresh blank Claude session in iris's container
+hivectl choom iris <session-id>   # resume an earlier choom session
 ```
 
-Each launch starts a fresh session named `choom` (claude mints its own
+With no session id, claude starts a fresh blank session (mints its own
-id), so it never collides with the harness's live session in the same
+id). Pass a session id to resume it (`claude --resume <id>`); you can
-project dir. The operator can rejoin a prior choom session later with
+rename it in-session. Either way choom never collides with the harness's
-`claude --resume choom`. The container must be running.
+live session in the same project dir: the harness pins its own id via
+`--resume`, so a blank choom session is invisible to it. The container
+must be running.
 
 choom reproduces the harness's own claude invocation so the operator
 lands in a faithful copy of the agent's environment:

hive-c0re/src/bin/hivectl.rs

@@ -112,13 +112,18 @@ enum Cmd {
     ///
     /// Execs `machinectl shell <name>@h-<name>` running claude as the
     /// agent user from its state dir, with the same settings / MCP config
-    /// / system prompt the harness uses. Each launch starts a fresh,
+    /// / system prompt the harness uses. Without a session id you get a
-    /// named ("choom") session so it never collides with the harness's
+    /// fresh blank session each launch; pass one to resume an earlier
-    /// live session in the same project dir. Requires root + a running
+    /// choom session (`--resume <id>`). Either way it never collides with
-    /// container.
+    /// the harness's live session — the harness pins its own session id
+    /// via `--resume`, so a blank choom session is invisible to it.
+    /// Requires root + a running container.
     Choom {
         /// Agent name (e.g. `damocles`, `iris`).
         name: String,
+        /// Optional session id to resume (`claude --resume <id>`). Omit
+        /// for a fresh blank session.
+        session: Option<String>,
     },
     /// Stop containers hive-wide in one operator action. Bare `hivectl
     /// stop` stops **everything** — all sub-agents plus the ci, forge,
@@ -625,7 +630,7 @@ async fn main() -> Result<()> {
         Cmd::Subvol { cmd } => match cmd {
             SubvolCmd::Upgrade { name, yes } => subvol_upgrade(&socket, &name, yes).await,
         },
-        Cmd::Choom { name } => choom(&name),
+        Cmd::Choom { name, session } => choom(&name, session.as_deref()),
         Cmd::Quota { cmd } => match cmd {
             QuotaCmd::Enable => quota_enable().await,
             QuotaCmd::Show { name } => quota_show(name.as_deref()).await,
@@ -1029,14 +1034,15 @@ fn agent_exists(name: &str) -> Result<bool> {
 /// 3. **Pass the harness's flags** (`--settings` / `--mcp-config` /
 ///    `--system-prompt-file` from `/run/hive-config/`), each only if its
 ///    file exists so a half-up container degrades to a bare session.
-/// 4. **Use a fresh, named session.** `--name choom` starts a brand-new
+/// 4. **Pick the session explicitly.** With no `session` arg, claude
-///    session (claude mints a random id) tagged "choom", so it never
+///    starts a fresh blank session (mints a random id). Pass a session
-///    resumes the harness's live session in this shared project dir. The
+///    id to resume it (`--resume <id>`); the operator can rename it
-///    operator can rejoin a prior choom session later via `claude
+///    in-session. Either way choom never clobbers the harness's live
-///    --resume choom`.
+///    session: the harness pins its own id via `--resume`, so a blank
+///    choom session in this shared project dir is invisible to it.
 ///
 /// Inherits the caller's PTY. Requires root + a running container.
-fn choom(name: &str) -> Result<()> {
+fn choom(name: &str, session: Option<&str>) -> Result<()> {
     if !agent_exists(name)? {
         bail!("no such agent: '{name}' (no state dir under /var/lib/hyperhive/agents/)");
     }
@@ -1053,15 +1059,33 @@ fn choom(name: &str) -> Result<()> {
     // `hive-config`); matches `hive-ag3nt::paths::config_dir()`. These
     // are the exact files the harness passes to claude each turn.
     let cfg = "/run/hive-config";
+    // A session id (if given) is resumed via `--resume <id>`; with none,
+    // claude starts a fresh blank session. The id is interpolated into
+    // the shell script, so constrain it to a safe charset first to rule
+    // out injection (real session ids are UUIDs).
+    let session_arg = match session {
+        Some(sid) => {
+            if sid.is_empty()
+                || !sid
+                    .bytes()
+                    .all(|b| b.is_ascii_alphanumeric() || b"-_.".contains(&b))
+            {
+                bail!(
+                    "invalid session id '{sid}': expected a claude session id (alphanumerics, '-', '_', '.')"
+                );
+            }
+            format!("set -- --resume {sid};")
+        }
+        None => "set --;".to_string(),
+    };
     // Build the claude argv as the harness does, but only include each
     // flag when its file is present so a half-up container falls back to
     // a bare session rather than a hard claude error. `name` is
-    // constrained to `[a-z0-9._-]` so there's nothing to quote.
+    // constrained to `[a-z0-9._-]` so there's nothing to quote. choom
-    // `--name choom` starts a fresh, named session each launch (claude
+    // never collides with the harness's live session in this same project
-    // mints its own id), so choom never collides with the harness's live
+    // dir: the harness pins its own session id via `--resume`.
-    // session in this same project dir; `--resume choom` rejoins it later.
     let inner = format!(
-        "cd {state_dir} || exit 1; set -- --name choom; \
+        "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; \