diff --git a/zenith/src/zenith_harness/acp_runner.py b/zenith/src/zenith_harness/acp_runner.py
index 26bfc8d..2d09ac7 100644
--- a/zenith/src/zenith_harness/acp_runner.py
+++ b/zenith/src/zenith_harness/acp_runner.py
@@ -95,14 +95,18 @@ def _augment_acp_command(command: str, provider) -> str:
     For codex-acp this is the no-ask, no-sandbox combo — equivalent to
     `codex --dangerously-bypass-approvals-and-sandbox`, which codex-acp
     does not expose as a flag but accepts via `-c` overrides.
+
+    For hermes the command is passed through unchanged.
     """
-    if getattr(provider, "name", None) == "codex":
+    name = getattr(provider, "name", None)
+    if name == "codex":
         return (
             command
             + ' -c sandbox_mode="danger-full-access"'
             + ' -c approval_policy="never"'
             + ' -c model_reasoning_effort="xhigh"'
         )
+    # hermes: no-op
     return command
 
 
@@ -113,12 +117,16 @@ def _acp_subprocess_env(provider) -> dict[str, str]:
     `/usr/bin/env node`, and pass sandbox-disable hints through env. The
     command line also receives `sandbox_mode="danger-full-access"` in
     `_augment_acp_command`.
+
+    For hermes the env is passed through unchanged.
     """
     env = os.environ.copy()
-    if getattr(provider, "name", None) == "codex":
+    name = getattr(provider, "name", None)
+    if name == "codex":
         # Env-var hints — harmless if codex ignores them.
         env["CODEX_SANDBOX"] = "danger-full-access"
         env["CODEX_DISABLE_SANDBOX"] = "1"
+    # hermes: no special env needed
     return env
 
 
diff --git a/zenith/src/zenith_harness/assets.py b/zenith/src/zenith_harness/assets.py
index a0ffe26..eb3d802 100644
--- a/zenith/src/zenith_harness/assets.py
+++ b/zenith/src/zenith_harness/assets.py
@@ -111,6 +111,9 @@ def bundled_agents_dir(self, provider_name: str) -> Path:
         """Per-provider subagents directory (`bundled/providers/<name>/agents/`)."""
         return self.config.bundled_dir / "providers" / provider_name / "agents"
 
+    def bundled_prompts_dir(self) -> Path:
+        return self.config.bundled_dir / "prompts"
+
     def _iter_skill_dirs(
         self, project_id: str | None
     ) -> list[tuple[Literal["project", "personal", "bundled"], Path]]:
diff --git a/zenith/src/zenith_harness/bundled/prompts/orchestrator/hermes_addendum.md b/zenith/src/zenith_harness/bundled/prompts/orchestrator/hermes_addendum.md
new file mode 100644
index 0000000..21df599
--- /dev/null
+++ b/zenith/src/zenith_harness/bundled/prompts/orchestrator/hermes_addendum.md
@@ -0,0 +1,72 @@
+# Hermes Addendum — Orchestrator Recall & Session Memory
+
+This addendum applies when Hermes is the orchestrator provider. It extends the base orchestrator prompt with Hermes-specific recall mechanisms.
+
+## Hermes Total Recall
+
+Hermes maintains a persistent session database (`~/.hermes/state.db` with FTS5) that survives across sessions, compressions, and restarts. Use it as a **queryable append-only log** of every zenith state read.
+
+### Recall Protocol
+
+**Before every `inspect_project` / `advance_project` / `decide_attention` call:**
+```
+session_search(query="project_id mission_id", role_filter="user,assistant,tool")
+```
+
+**After every MCP tool call that returns zenith state:**
+```
+memory(action="add", target="memory", content="zenith state: {project_id} {mission_id} {state} {key_findings}")
+```
+
+### Query Patterns
+
+| Need | Query |
+|------|-------|
+| Last known state | `session_search(query="project_id state", limit=1, sort="newest")` |
+| All attention items | `session_search(query="attention_needed project_id", limit=10)` |
+| Decision history | `session_search(query="decide_attention project_id", role_filter="assistant,tool")` |
+| Contract changes | `session_search(query="contract VAL- project_id", limit=20)` |
+| Failed tasks | `session_search(query="failed project_id", limit=10)` |
+
+### Memory Promotion
+
+When Hermes session compression drops context, **promote critical findings to Zenith disk state first:**
+
+```python
+# Before compression triggers (at ~50% threshold):
+# 1. Write to mission.md / MEMORY.md / decisions/
+# 2. Then let Hermes compress
+```
+
+The Zenith disk state (`brief.md`, `mission.md`, `contract/`, `decisions/`, `MEMORY.md`) is the **canonical memory**. Hermes session DB is the **audit trail**.
+
+### Skills Loading
+
+Hermes loads skills from:
+- `.hermes/skills/` (project-specific, written by `zenith init`)
+- `~/.hermes/skills/` (user-installed)
+- Bundled skills (copied to `.hermes/skills/` by `zenith init`)
+
+To load a skill mid-mission: `/skill engineering-mission-playbook` or `hermes -s engineering-mission-playbook chat ...`
+
+### Compression Awareness
+
+Default threshold: 50% context window. Lower for zenith missions:
+```bash
+hermes config set compression.threshold 0.3
+hermes config set compression.target_ratio 0.2
+```
+
+### Slash Commands in Mission
+
+| Command | Use |
+|---------|-----|
+| `/inspect` | Show current session info (tokens, tools, skills) |
+| `/memory` | Search/add memory entries |
+| `/session_search` | Query past zenith sessions |
+| `/skill <name>` | Load a skill |
+| `/reload-skills` | Re-scan skill directories |
+
+---
+
+**Rule:** Every zenith state transition (start_project → submit_plan → advance_project → attention → decide → advance → end_mission) should leave a trace in both Hermes session DB *and* Zenith disk state. The disk state is the contract; the session DB is the witness.
\ No newline at end of file
diff --git a/zenith/src/zenith_harness/cli.py b/zenith/src/zenith_harness/cli.py
index 7e20918..ec68677 100644
--- a/zenith/src/zenith_harness/cli.py
+++ b/zenith/src/zenith_harness/cli.py
@@ -442,6 +442,11 @@ def _setup_provider_assets(
         if not path.exists():
             path.parent.mkdir(parents=True, exist_ok=True)
             body = loader.load_prompt_file("orchestrator", "system_prompt.md")
+            # Append Hermes-specific addendum for Hermes provider
+            if provider.name == "hermes":
+                addendum_path = loader.bundled_prompts_dir() / "orchestrator" / "hermes_addendum.md"
+                if addendum_path.exists():
+                    body += "\n\n---\n\n" + addendum_path.read_text(encoding="utf-8")
             path.write_text(body, encoding="utf-8")
             click.echo(f"Created {path}")
 
diff --git a/zenith/src/zenith_harness/coordinator.py b/zenith/src/zenith_harness/coordinator.py
index 3fa17bb..3c11bef 100644
--- a/zenith/src/zenith_harness/coordinator.py
+++ b/zenith/src/zenith_harness/coordinator.py
@@ -284,15 +284,18 @@ def _dispatch_batch(
         handoffs = self._dispatch_requests(requests)
 
         attention: list[AttentionItemInternal] = []
+        # Batch write all attempts to disk concurrently
+        self.store.save_attempts(
+            self.project_id,
+            mid,
+            [
+                (attempt.spawn_ts, attempt.task.id, handoffs[attempt.task.id])
+                for attempt in sorted(batch_attempts, key=lambda item: item.task.id)
+            ]
+        )
+
         for attempt in sorted(batch_attempts, key=lambda item: item.task.id):
             handoff = handoffs[attempt.task.id]
-            self.store.save_attempt(
-                self.project_id,
-                mid,
-                attempt.spawn_ts,
-                attempt.task.id,
-                handoff,
-            )
             attention.extend(
                 self._apply_handoff_collect(mid, attempt.task, handoff, attempt.spawn_ts)
             )
diff --git a/zenith/src/zenith_harness/providers.py b/zenith/src/zenith_harness/providers.py
index 4c24d51..69043c5 100644
--- a/zenith/src/zenith_harness/providers.py
+++ b/zenith/src/zenith_harness/providers.py
@@ -3,16 +3,18 @@
 from dataclasses import dataclass
 from typing import Literal
 
-ProviderName = Literal["claude", "codex"]
+ProviderName = Literal["claude", "codex", "hermes"]
 ConfigFormat = Literal["mcp_json", "codex_config"]
 
 ORCHESTRATOR_PROVIDER_NAMES: tuple[ProviderName, ...] = (
     "claude",
     "codex",
+    "hermes",
 )
 WORKER_PROVIDER_NAMES: tuple[ProviderName, ...] = (
     "claude",
     "codex",
+    "hermes",
 )
 
 
@@ -138,6 +140,17 @@ def _dedupe_paths(paths: tuple[str, ...]) -> tuple[str, ...]:
         orchestrator_prompt_output_path=".codex/orchestrator_prompt.md",
         acp_supports_system_prompt=False,
     ),
+    "hermes": ProviderDefinition(
+        name="hermes",
+        skill_dirs=(".hermes/skills", ".agents/skills"),
+        skill_alias_dirs=(".hermes/skills", ".agents/skills"),
+        config_format="mcp_json",
+        default_worker_acp_command="hermes acp",
+        agent_output_dir=".hermes/agents",
+        orchestrator_prompt_output_path=".hermes/orchestrator_prompt.md",
+        acp_supports_system_prompt=True,
+        acp_runtime_mode=None,
+    ),
 }
 
 
diff --git a/zenith/src/zenith_harness/storage.py b/zenith/src/zenith_harness/storage.py
index da1d9c0..07b514b 100644
--- a/zenith/src/zenith_harness/storage.py
+++ b/zenith/src/zenith_harness/storage.py
@@ -19,6 +19,8 @@
 import os
 import re
 import shutil
+import concurrent.futures
+
 from dataclasses import dataclass
 from datetime import UTC, datetime
 from pathlib import Path
@@ -443,6 +445,22 @@ def save_attempt(
         atomic_write_text(md_path, attempt_to_markdown(handoff))
         return json_path
 
+
+    def save_attempts(
+        self,
+        project_id: str,
+        mission_id: str,
+        items: list[tuple[str, str, WorkHandoff | ValidateHandoff]],
+    ) -> None:
+        def save_one(item: tuple[str, str, WorkHandoff | ValidateHandoff]) -> None:
+            spawn_ts, node_id, handoff = item
+            self.save_attempt(project_id, mission_id, spawn_ts, node_id, handoff)
+
+        workers = min(32, (os.cpu_count() or 1) + 4)
+        with concurrent.futures.ThreadPoolExecutor(max_workers=workers) as executor:
+            # list() to force evaluation and wait for completion/errors
+            list(executor.map(save_one, items))
+
     def read_attempt(
         self,
         project_id: str,