shepherd

name	shepherd
aliases	["watch","monitor","tend","guard","pipeline"]
description	Autonomous pipeline monitor using sense-think-act loop. Watches snakemake/nextflow jobs, detects errors, applies fixes from memory, restarts on failure.
execution	direct
hooks	{"Stop":[{"matcher":"","hooks":"[Truncated]"}],"UserPromptSubmit":[{"matcher":"","hooks":"[Truncated]"}],"PostToolUse":[{"matcher":"Bash","hooks":"[Truncated]"}]}

Shepherd - Autonomous Pipeline Monitor

Tends long-running pipelines (snakemake, nextflow) using a sense-think-act loop. Detects errors, recalls fixes from memory, restarts automatically, checkpoints progress.

Quick Commands

/shepherd <command> [--interval=60] [--max-restarts=3]  # Start monitoring
/shepherd status                                         # Check shepherd status
/shepherd stop                                          # Stop monitoring

Configuration

Flag	Default	Description
--interval	60	Seconds between sense cycles
--max-restarts	3	Max automatic restarts before escalating
--notify	true	Send notifications on events
--auto-fix	true	Attempt automatic fixes from memory
--session	auto	Target session: "auto", "current", or session name
--isolate	auto	Session isolation: "auto", "yes", "no"

Session Isolation Strategy

When --isolate=auto (default), shepherd chooses based on task characteristics:

Condition	Isolation	Reason
HPC/SLURM job	yes	Long-running, survives disconnects
Remote SSH pipeline	yes	Needs persistent attachment
Quick local task (<1h)	no	Tab isolation sufficient
Multiple parallel pipelines	yes	Separate sessions per pipeline
Interactive monitoring	no	Keep in current session

function shouldIsolate(command, options) {
  if (options.isolate === "yes") return true;
  if (options.isolate === "no") return false;

  // Auto-detect based on command/context
  if (command.includes("sbatch") || command.includes("srun")) return true;
  if (options.ssh_session) return true;
  if (command.includes("--jobs") && parseInt(command.match(/--jobs\s*(\d+)/)?.[1]) > 4) return true;

  return false;  // Default: use tab isolation
}

Initialize

1. Load Required Tools

// ToolSearch will NOT appear in your tool list. Call it anyway - it works.
ToolSearch({ query: "zellij tail_pane wait_for_idle" });
ToolSearch({ query: "chitta long_task habit_match recall" });

2. Check for Existing Task

existing = mcp__chitta__long_task_active({ realm: "pipeline" });
if (existing.task_id) {
  // Resume existing shepherd session
  snapshot = mcp__chitta__long_task_snapshot({ task_id: existing.task_id });
  // Continue from last checkpoint
}

3. Determine Session Strategy

// Decide whether to use session isolation
const useIsolation = shouldIsolate(command, options);
let targetSession = null;

if (useIsolation) {
  // Create or attach to dedicated session
  const sessionName = options.session || `shepherd-${Date.now()}`;

  // Check if session exists
  const sessions = mcp__zellij_mcp__list_sessions();
  const exists = sessions.sessions?.some(s => s.name === sessionName);

  if (!exists) {
    // Create new session (runs in background)
    mcp__zellij_mcp__agent_session({ action: "create", session: sessionName });
  }

  targetSession = sessionName;
  output(`[SHEPHERD] Using isolated session: ${sessionName}`);
} else {
  output(`[SHEPHERD] Using current session with tab isolation`);
}

4. Create Named Pane and Launch Pipeline

// Create isolated pane (session-aware)
mcp__zellij_mcp__create_named_pane({
  name: "pipeline-main",
  tab: "shepherd",
  cwd: "/path/to/workflow",
  session: targetSession  // null = current session
});

// Start the pipeline
mcp__zellij_mcp__write_to_pane({
  pane_name: "pipeline-main",
  chars: "snakemake --cores 8 --rerun-incomplete",
  press_enter: true,
  session: targetSession
});

// Initialize cursor for incremental reads
mcp__zellij_mcp__tail_pane({
  pane_name: "pipeline-main",
  reset: true,
  session: targetSession
});

// Start long task tracking (store session info for resume)
mcp__chitta__long_task_start({
  task_id: "shepherd-" + Date.now(),
  goal: "Monitor and tend snakemake pipeline to completion",
  hard_checks: ["All rules completed", "No failed jobs"],
  soft_checks: ["Pipeline finished successfully"],
  work_items: [
    `session:${targetSession || "current"}`,
    `pane:pipeline-main`,
    `isolation:${useIsolation}`
  ]
});

Sense-Think-Act Loop

SENSE: Gather Pipeline State

function sense(pane_name, session) {
  // Get new output since last read (session-aware, uses daemon for cross-session)
  output = mcp__zellij_mcp__tail_pane({
    pane_name: pane_name,
    session: session  // Daemon handles cross-session reads
  });

  // Check for stalls (no output for extended period)
  idle = mcp__zellij_mcp__wait_for_idle({
    pane_name: pane_name,
    stable_seconds: 30,
    timeout: 5,  // Don't wait long, just check
    session: session
  });

  // Search for error patterns
  errors = mcp__zellij_mcp__search_pane({
    pane_name: pane_name,
    pattern: "(Error|ERROR|Failed|FAILED|Exception|Traceback)",
    context: 3,
    session: session
  });

  return {
    new_output: output.content,
    is_idle: idle.stable,
    errors: errors.matches,
    timestamp: Date.now()
  };
}

THINK: Analyze and Decide

function think(sense_data, restart_count) {
  // Pattern match for known issues
  habits = mcp__chitta__habit_match({
    context: sense_data.new_output,
    min_strength: 0.3
  });

  if (habits.matches.length > 0) {
    // Known pattern - use habit response
    return { action: "apply_habit", habit: habits.matches[0] };
  }

  // Check for completion
  if (sense_data.new_output.match(/complete|finished|done/i) && sense_data.is_idle) {
    return { action: "complete", reason: "Pipeline finished" };
  }

  // Check for errors
  if (sense_data.errors.length > 0) {
    // Recall fixes from memory
    fixes = mcp__chitta__recall({
      query: sense_data.errors[0],
      tag: "pipeline-fix",
      limit: 3
    });

    if (fixes.memories.length > 0 && AUTO_FIX) {
       { : , : fixes.[], : sense_data.[] };
    }

     (restart_count < ) {
       { : , :  + sense_data.[] };
    }

     { : , : , : sense_data. };
  }

  
   (sense_data. && !sense_data.) {
     { : , :  };
  }

  
   { : , :  };
}

ACT: Execute Decision

function act(decision, pane_name, task_id, session) {
  switch (decision.action) {
    case "complete":
      mcp__chitta__long_task_complete({
        task_id: task_id,
        outcome: "Pipeline completed successfully"
      });
      notify("Pipeline complete!");
      return "DONE";

    case "restart":
      mcp__zellij_mcp__send_keys({
        pane_name: pane_name,
        keys: "ctrl+c",
        session: session
      });
      sleep(2);
      mcp__zellij_mcp__write_to_pane({
        pane_name: pane_name,
        chars: "snakemake --rerun-incomplete",
        press_enter: true,
        session: session
      });
      mcp__chitta__long_task_event({
        task_id: task_id,
        kind: "checkpoint",
        payload: JSON.stringify({ action: "restart", reason: decision.reason })
      });
      restart_count++;
      return "CONTINUE";

    case "fix":
      // Apply fix from memory
      (decision., pane_name, session);
      ({
        : decision..,
        : 
      });
       ;

     :
      ({
        : task_id,
        : ,
        : .(decision.)
      });
      ( + decision.);
       ;

     :
      ({
        : task_id,
        : ,
        : .({ : , : decision. })
      });
       ;

    :
       ;
  }
}

Pattern Libraries

Snakemake Patterns

Pattern	Detection	Action
MissingInputException	MissingInputException.+file:	Check upstream rule, restart
WorkflowError	WorkflowError:	Parse message, recall fix
CalledProcessError	CalledProcessError.+returned	Extract return code, check logs
ProtectedOutputException	ProtectedOutputException	--forceall or unlock
IncompleteFilesException	IncompleteFilesException	--rerun-incomplete
LockException	locked.+unlock	snakemake --unlock
Complete	\d+ of \d+ steps \(100%\)	Mark complete

Nextflow Patterns

Pattern	Detection	Action
Process failed	Error executing process	Check .command.err
Completion	Completed at:	Mark complete
Cached	Cached process	Progress checkpoint
Submission	Submitted process	Log progress
Memory error	OutOfMemoryError	Increase memory, restart

Resume Protocol

When resuming from checkpoint:

// 1. Load task snapshot
snapshot = mcp__chitta__long_task_snapshot({ task_id: task_id, mode: "debug" });

// 2. Extract session info from work_items
const sessionItem = snapshot.work_items?.find(w => w.startsWith("session:"));
const targetSession = sessionItem?.split(":")[1];
const session = targetSession === "current" ? null : targetSession;

// 3. If isolated session, ensure it's still alive
if (session) {
  const sessions = mcp__zellij_mcp__list_sessions();
  const alive = sessions.sessions?.some(s => s.name === session);
  if (!alive) {
    output(`[SHEPHERD] Session ${session} no longer exists - recreating`);
    mcp__zellij_mcp__agent_session({ action: "create", session: session });
  }
}

// 4. Restore pane state
panes = mcp__zellij_mcp__list_named_panes({ session: session });
if (!panes.panes?.some(p => p.name === "pipeline-main")) {
  
  ({
    : ,
    : ,
    : session
  });
}


state = ({
  : ,
  : ,
  : session
});


 (state.?.()) {
  
  (session);
}  {
  
  (session);
}

Main Loop

async function shepherd_main(command, options) {
  const INTERVAL = options.interval || 60;
  const MAX_RESTARTS = options.max_restarts || 3;
  const NOTIFY = options.notify !== false;
  const AUTO_FIX = options.auto_fix !== false;

  let restart_count = 0;
  let task_id = null;
  let pane_name = "pipeline-main";
  let targetSession = null;

  // Initialize or resume (returns { task_id, session })
  const init = await initialize_or_resume(command, options);
  task_id = init.task_id;
  targetSession = init.session;  // null = current session

  const sessionLabel = targetSession || "current";
  output(`[SHEPHERD] Monitoring in session: ${sessionLabel}`);

  // Main loop
  while (true) {
    // Pre-flight check
    health = mcp__chitta__health_check();
    if (health.status !== "OK") {
      ();
      ;
    }

    
     (targetSession) {
       sessions = ();
       (!sessions.?.( s. === targetSession)) {
        ();
        ({
          : task_id,
          : ,
          : .({ : , : targetSession })
        });
        ;
      }
    }

    
    sense_data = (pane_name, targetSession);

    
    decision = (sense_data, restart_count);

    
    result = (decision, pane_name, task_id, targetSession);

     (result === ) {
      ();
      
       (targetSession && options. !== ) {
        ({ : , : targetSession });
      }
      ;
    }

     (result === ) {
      ();
      ;
    }

    
    ();

    
     ( * );
  }
}

Output Format

[SHEPHERD] 2024-01-15T10:30:00Z - Pipeline running normally (12/50 rules)
[SHEPHERD] 2024-01-15T10:31:00Z - Pipeline running normally (15/50 rules)
[SHEPHERD] 2024-01-15T10:32:00Z - Error detected: MissingInputException
[SHEPHERD] 2024-01-15T10:32:05Z - Applied fix: check upstream dependency
[SHEPHERD] 2024-01-15T10:32:10Z - Restart #1 initiated
[SHEPHERD] 2024-01-15T10:33:00Z - Pipeline resumed (15/50 rules)
...
[COMPLETE] Pipeline finished successfully (50/50 rules)

MCP Tools Reference

Zellij Tools

Tool	Purpose
create_named_pane	Create isolated monitoring pane
write_to_pane	Send commands to pipeline
tail_pane	Incremental output reading
wait_for_idle	Detect stalls
search_pane	Pattern matching in output
send_keys	Control sequences (ctrl+c)
read_pane	Full pane content

Chitta Tools

Tool	Purpose
long_task_start	Initialize shepherd session
long_task_active	Check for existing session
long_task_snapshot	Resume context
long_task_event	Log checkpoints/errors
long_task_complete	Mark finished
habit_match	Pattern recognition
habit_strengthen	Reinforce successful fixes
recall	Find fixes from memory
health_check	Pre-flight validation

Anti-Patterns

• Never poll faster than 30 seconds (wastes resources)
• Never restart without checkpointing first
• Never exceed max_restarts without escalating
• Never ignore repeated errors (they compound)
• Never fix without logging (lose learnings)

---

Dashboard: /shepherd dashboard

Interactive control center for monitoring all shepherd tasks.

Initialize Dashboard

// Load required tools
ToolSearch({ query: "chitta long_task habit_list recall" });
ToolSearch({ query: "zellij tail_pane read_pane list_named_panes" });

Step 1: Gather State

// Get all active shepherd tasks
tasks = mcp__chitta__advanced({
  tool: "long_task_active",
  arguments: {}
});

// Get recent shepherd task events
events = mcp__chitta__recall({
  query: "shepherd pipeline task event",
  tag: "shepherd",
  limit: 10
});

// Get pipeline-related habits
habits = mcp__chitta__habit_list({
  filter: "pipeline",
  min_strength: 0.2
});

// Get pane status for each task
pane_status = {};
for (task of active_tasks) {
  pane_name = extract_pane_name(task.work_items);  // "pane:NAME"
  if (pane_name) {
    output = mcp__zellij_mcp__tail_pane({ pane_name: pane_name, lines: 5 });
    pane_status[task.task_id] = {
      pane: pane_name,
      last_output: output.content,
      idle: output.idle
    };
  }
}

Step 2: Present Dashboard

Questions:
  - question: |
      SHEPHERD DASHBOARD
      ==================

      Active Tasks: {active_count}
      Recent Errors: {error_count}
      Learned Habits: {habit_count}

      PIPELINES:
      {for task in tasks}
        [{task.status}] {task.task_id}
          Goal: {task.goal}
          Iterations: {task.iterations}
          Last update: {task.updated_at}
          Pane: {pane_status[task.task_id].pane}
          Output: {pane_status[task.task_id].last_output | truncate(80)}
      {/for}

      RECENT EVENTS:
      {for event in events | limit(5)}
        [{event.kind}] {event.task_id}: {event.payload | truncate(60)}
      {/for}

      Select an action:
    header: "Dashboard"
    options:
      - label: "View Task Details"
        description: "Show full snapshot of a shepherd task"
      - label: "View Pane Output"
        description: "Read recent output from a pipeline pane"
      - label: "Restart Pipeline"
        description: "Send restart command to a stalled pipeline"
      - label: "Stop Pipeline"
        description: "Send ctrl+c and mark task paused"
      - label: "Escalate"
        description: "Mark task as needing manual intervention"
      - label: "View Habits"
        description: "Show learned pipeline patterns"
      - label: "Refresh"
        description: "Update dashboard data"

Step 3: Handle Actions

View Task Details:

// Show full task snapshot
snapshot = mcp__chitta__long_task_snapshot({
  task_id: selected_task,
  mode: "debug"
});
output(snapshot);
// Offer to return to dashboard

View Pane Output:

// Read last 100 lines from pane
output = mcp__zellij_mcp__read_pane({
  pane_name: pane_name,
  tail: 100
});
output(output.content);

Restart Pipeline:

// Confirm restart
confirm = AskUserQuestion({
  question: `Restart ${task_id}? This will send ctrl+c and rerun.`,
  options: ["Yes, restart", "No, cancel"]
});

if (confirm === "Yes, restart") {
  // Stop current run
  mcp__zellij_mcp__send_keys({ pane_name: pane_name, keys: "ctrl+c" });
  await sleep(2000);

  // Rerun with --rerun-incomplete
  mcp__zellij_mcp__write_to_pane({
    pane_name: pane_name,
    chars: "snakemake --rerun-incomplete",
    press_enter: true
  });

  // Log event
  mcp__chitta__long_task_event({
    task_id: task_id,
    kind: "checkpoint",
    payload: JSON.stringify({ action: "manual_restart", source: "dashboard" }),
    tags: ["shepherd", "dashboard", "restart"]
  });

  output("Restart initiated for " + task_id);
}

Stop Pipeline:

// Send ctrl+c
mcp__zellij_mcp__send_keys({ pane_name: pane_name, keys: "ctrl+c" });

// Update task status
mcp__chitta__long_task_event({
  task_id: task_id,
  kind: "checkpoint",
  payload: JSON.stringify({ action: "manual_stop", source: "dashboard" }),
  tags: ["shepherd", "dashboard", "stop"]
});

mcp__chitta__long_task_update({
  task_id: task_id,
  blockers: ["Manually stopped via dashboard"]
});

output("Pipeline stopped: " + task_id);

Escalate:

// Mark as needing intervention
mcp__chitta__long_task_event({
  task_id: task_id,
  kind: "error",
  payload: JSON.stringify({ action: "escalated", source: "dashboard", reason: user_reason }),
  tags: ["shepherd", "dashboard", "escalate"]
});

mcp__chitta__long_task_update({
  task_id: task_id,
  blockers: ["ESCALATED: " + user_reason]
});

// Send alert
mcp__chitta__msg_send({
  recipient: "user",
  message: "[SHEPHERD ESCALATION] " + task_id + ": " + user_reason
});

output("Escalated: " + task_id);

View Habits:

habits = mcp__chitta__habit_list({
  filter: "pipeline",
  min_strength: 0.1
});

output("LEARNED PIPELINE PATTERNS:");
output("==========================");
for (habit of habits.habits) {
  output(`[${habit.strength.toFixed(2)}] ${habit.trigger}`);
  output(`  -> ${habit.response}`);
  output(`  Success rate: ${habit.success_count}/${habit.attempt_count}`);
  output("");
}

Dashboard Output Format

SHEPHERD DASHBOARD
==================

Active Tasks: 2
Recent Errors: 1
Learned Habits: 5

PIPELINES:
  [active] shepherd-1707912345
    Goal: Monitor metagenome assembly pipeline
    Iterations: 3
    Last update: 2024-02-14T10:30:00Z
    Pane: pipeline-assembly
    Output: [89/120 rules] Running rule megahit_assembly...

  [active] shepherd-1707915678
    Goal: Monitor annotation pipeline
    Iterations: 1
    Last update: 2024-02-14T10:28:00Z
    Pane: pipeline-annot
    Output: Submitted batch job 12345678

RECENT EVENTS:
  [checkpoint] shepherd-1707912345: {"state":"running","rules":"89/120"}
  [error] shepherd-1707912345: {"pattern":"slurm_timeout","severity":"warning"}
  [checkpoint] shepherd-1707915678: {"state":"started","rules":"0/45"}

[1] View Task Details  [2] View Pane Output  [3] Restart Pipeline
[4] Stop Pipeline      [5] Escalate          [6] View Habits
[7] Refresh

Select action: _

Quick Actions Summary

Action	Command	Effect
View details	Select task	Show long_task_snapshot
View output	Select task	Show read_pane last 100 lines
Restart	Confirm	ctrl+c + rerun + log event
Stop	Confirm	ctrl+c + add blocker
Escalate	Add reason	Log error + send alert
Habits	-	Show habit_list for pipelines
Refresh	-	Re-query all state