feat(missions): bring the direct session executor onto a live branch

Rescues session_executor from the stranded spike branch. Multi-provider
missions are not needed for now, so the direct path is worth nailing down:
run a mission as one `claude -p` session against its checkout instead of
routing turns through ZeroClaw.

Measured today against a real checkout in the runtime container, using the
executor's exact argv:

  direct `claude -p`   7s, file written
  via ZeroClaw         minutes per turn, and THREE config failures before
                       it worked at all (no credential in the mission
                       container; Write/Edit denied; no tools granted --
                       the last of which COMPLETED a mission having
                       written nothing)

Each of those failures came from the same root: with claude_cli, ZeroClaw
is a WebSocket-to-subprocess adapter whose own controls (risk profiles,
tool gating, memory) do not reach the subprocess. The adapter adds
failure modes without adding governance.

What ZeroClaw still earns for the rest of the platform is unchanged and
not in question here: interactive chat, the brain, A2A and door identity,
terminal, agent routines, and non-Claude providers.

Not yet wired into phase_runner — this commit only makes the executor
reachable and keeps it building. SessionOutcome::delivered() still
requires a clean exit AND an observed branch, because a 0-exit session
that pushed nothing was measured at ~5%.

405 tests, clippy clean.

Co-Authored-By: Claude Opus 5 <[email protected]>

crates/cm-api/src/lib.rs

@@ -23,6 +23,7 @@ pub mod library;
 pub mod mission_delivery;
 pub mod papers;
 pub mod phase_config;
+pub mod session_executor;
 pub mod runtime_preflight;
 pub mod mission_runtime;
 pub mod mission_workspace;

crates/cm-api/src/session_executor.rs

@@ -0,0 +1,238 @@
+//! Run a whole mission as ONE headless agent session.
+//!
+//! The alternative to `phase_runner`. Instead of splitting a mission into
+//! phases that hand work to each other through a shared checkout, this hands
+//! the entire task to a single agent session and asks the forge afterwards
+//! what actually landed.
+//!
+//! # Why
+//!
+//! The phase machinery moves state between processes through a filesystem, and
+//! that seam produced most of a week's defects: two uids fighting over
+//! `.git/objects`, a missing git identity, `reset --hard` deleting the
+//! previous phase's work, a capture base overloaded with two meanings. None of
+//! those failures are *possible* inside one session, because there is no
+//! handoff to get wrong — step two knows what step one did because it is the
+//! same context.
+//!
+//! Measured against the same task (create a file, read it back, extend it,
+//! push it): the phase path took nine production runs and five distinct bug
+//! fixes to do reliably; a single session did it in 23 seconds, 19 times out
+//! of 20, first try.
+//!
+//! # What this deliberately does NOT trust
+//!
+//! The agent's own account of what it did. In the same 60-run experiment one
+//! session exited 0, ran for 18 seconds, and pushed nothing — a clean exit
+//! status with no work delivered, about 5% of the time. That is the same
+//! "reported success while doing nothing" shape as every scaffolding bug, and
+//! it is why [`verify_landed`] asks the forge rather than reading the summary.
+//!
+//! Deleting the phase machinery is justified by the evidence. Deleting the
+//! verification is not — the evidence points the other way.
+
+use std::time::Duration;
+use uuid::Uuid;
+
+use crate::container_exec;
+
+/// Ceiling for one mission session. Long, because a real coding task with a
+/// test suite legitimately takes minutes; bounded, because a wedged session
+/// must not hold a container forever.
+const SESSION_TIMEOUT: Duration = Duration::from_secs(3600);
+
+/// Tools the session may use without prompting.
+///
+/// `--dangerously-skip-permissions` is refused by the CLI when running as
+/// root, which mission containers do, and blanket bypass is the wrong default
+/// for something driving a real repository anyway. An explicit allow-list is
+/// both accepted as root and easier to defend.
+const ALLOWED_TOOLS: &[&str] = &["Read", "Edit", "Write", "Bash"];
+
+/// What one session did, as observed from outside it.
+#[derive(Debug, Clone)]
+pub struct SessionOutcome {
+    /// The agent's closing summary. Diagnostic only — never evidence.
+    pub summary: String,
+    pub exit_code: Option<i64>,
+    /// Whether the expected branch actually appeared on the forge.
+    pub landed: bool,
+    /// Head sha of the branch, when it landed.
+    pub head_sha: Option<String>,
+}
+
+impl SessionOutcome {
+    /// The session both finished cleanly *and* delivered.
+    ///
+    /// Both halves are required. `exit_code == Some(0)` alone is what the
+    /// 5% silent-nothing case looks like from the inside.
+    pub fn delivered(&self) -> bool {
+        self.exit_code == Some(0) && self.landed
+    }
+}
+
+/// Build the instruction for a mission session.
+///
+/// One statement of the whole job, not a per-phase directive. The branch name
+/// is stated rather than left to the agent so there is a fixed thing to verify
+/// against afterwards — an agent that picks its own branch name is an agent
+/// whose work cannot be checked without asking it where the work went.
+pub fn session_prompt(task: &str, repo_path: &str, branch: &str) -> String {
+    format!(
+        "You are working in the git repository at {repo_path}.\n\
+         \n\
+         TASK\n\
+         {task}\n\
+         \n\
+         WHEN THE WORK IS DONE\n\
+         Commit it and push to a new branch named exactly `{branch}`.\n\
+         The remote `origin` is already configured with credentials.\n\
+         \n\
+         If the task cannot be completed as written — a file it refers to does \
+         not exist, a premise is wrong, the tests cannot run — say so plainly \
+         and do NOT push. An honest report that the work could not be done is \
+         worth more than a branch that looks finished.\n"
+    )
+}
+
+/// Run one mission session inside an existing container.
+pub async fn run_session(
+    container: &str,
+    repo_path: &str,
+    task: &str,
+    branch: &str,
+) -> Result<(String, Option<i64>), String> {
+    let docker = container_exec::connect()?;
+    let prompt = session_prompt(task, repo_path, branch);
+    let mut argv = vec!["claude".to_string(), "-p".to_string()];
+    argv.push("--allowedTools".into());
+    argv.extend(ALLOWED_TOOLS.iter().map(|t| t.to_string()));
+    argv.push("--permission-mode".into());
+    argv.push("acceptEdits".into());
+    argv.push(prompt);
+
+    let out = container_exec::exec(
+        &docker,
+        container,
+        Some(repo_path),
+        &argv,
+        SESSION_TIMEOUT,
+    )
+    .await?;
+    Ok((out.combined(), out.exit_code))
+}
+
+/// Ask the forge whether the branch exists, and at what commit.
+///
+/// The whole point of the module. Everything above this line is the agent's
+/// account of events; this is the only part that is evidence.
+pub async fn verify_landed(
+    api_base: &str,
+    token: &str,
+    branch: &str,
+) -> Result<Option<String>, String> {
+    let url = format!("{api_base}/branches/{}", urlencode(branch));
+    let client = reqwest::Client::new();
+    let resp = client
+        .get(&url)
+        .header("Authorization", format!("token {token}"))
+        .timeout(Duration::from_secs(30))
+        .send()
+        .await
+        .map_err(|e| format!("query branch: {e}"))?;
+    if resp.status().as_u16() == 404 {
+        return Ok(None);
+    }
+    if !resp.status().is_success() {
+        return Err(format!("forge returned {}", resp.status()));
+    }
+    let body: serde_json::Value = resp
+        .json()
+        .await
+        .map_err(|e| format!("decode branch response: {e}"))?;
+    Ok(body
+        .get("commit")
+        .and_then(|c| c.get("id"))
+        .and_then(|v| v.as_str())
+        .map(str::to_string))
+}
+
+/// Percent-encode the path segment. Branch names contain `/`, which would
+/// otherwise split the URL path and query the wrong endpoint.
+fn urlencode(s: &str) -> String {
+    s.bytes()
+        .map(|b| match b {
+            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => {
+                (b as char).to_string()
+            }
+            _ => format!("%{b:02X}"),
+        })
+        .collect()
+}
+
+/// Branch a session-executed mission pushes to.
+pub fn session_branch(mission_id: Uuid) -> String {
+    format!("clawmates/session-{}", &mission_id.simple().to_string()[..12])
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn the_prompt_names_the_branch_and_forbids_a_dishonest_push() {
+        let p = session_prompt("Add a file.", "/mission/repo", "clawmates/session-abc");
+        assert!(p.contains("clawmates/session-abc"), "branch must be fixed");
+        assert!(p.contains("/mission/repo"));
+        assert!(
+            p.contains("do NOT push"),
+            "the prompt must give an honest exit that is not a branch"
+        );
+    }
+
+    /// A clean exit is not delivery. This is the 5% case from the 60-run
+    /// experiment: `rc=0`, 18 seconds of work, no branch.
+    #[test]
+    fn a_clean_exit_without_a_branch_is_not_delivery() {
+        let silent = SessionOutcome {
+            summary: "All steps completed.".into(),
+            exit_code: Some(0),
+            landed: false,
+            head_sha: None,
+        };
+        assert!(
+            !silent.delivered(),
+            "exit 0 with nothing on the forge must never count as delivered"
+        );
+
+        let real = SessionOutcome {
+            landed: true,
+            head_sha: Some("abc123".into()),
+            ..silent.clone()
+        };
+        assert!(real.delivered());
+
+        // And a failed session that somehow pushed is also not a success.
+        let broken = SessionOutcome {
+            exit_code: Some(1),
+            landed: true,
+            head_sha: Some("abc123".into()),
+            summary: String::new(),
+        };
+        assert!(!broken.delivered());
+    }
+
+    #[test]
+    fn branch_names_survive_url_encoding() {
+        assert_eq!(urlencode("clawmates/session-01"), "clawmates%2Fsession-01");
+        assert_eq!(urlencode("plain"), "plain");
+    }
+
+    #[test]
+    fn a_session_branch_is_stable_and_namespaced() {
+        let id = Uuid::now_v7();
+        let b = session_branch(id);
+        assert_eq!(b, session_branch(id));
+        assert!(b.starts_with("clawmates/session-"));
+    }
+}