diff --git a/Cargo.lock b/Cargo.lock
index 011688b6..28a1a7d2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1376,6 +1376,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "futures-util",
+ "hive-sh4re",
  "matrix-sdk",
  "reqwest",
  "rmcp",
diff --git a/hive-ag3nt/src/mcp_loose_ends.rs b/hive-ag3nt/src/mcp_loose_ends.rs
index c61f4260..7b6f4aad 100644
--- a/hive-ag3nt/src/mcp_loose_ends.rs
+++ b/hive-ag3nt/src/mcp_loose_ends.rs
@@ -10,20 +10,10 @@
 
 use std::path::PathBuf;
 
-/// NOTE: the base-dir resolution logic here is intentionally mirrored in
-/// `hive-bash-mcp/src/paths.rs::mcp_loose_ends_dir()`. They can't share
-/// code across crates — keep them in sync if the fallback logic changes.
+/// Resolution lives in `hive_sh4re::paths` so the harness + every MCP
+/// daemon agree on where loose-end summary files are written.
 fn loose_ends_dir() -> PathBuf {
-    let base = if let Some(p) = std::env::var_os("HYPERHIVE_HARNESS_DIR") {
-        PathBuf::from(p)
-    } else {
-        let state = std::env::var("HYPERHIVE_STATE_DIR").unwrap_or_default();
-        let state_path = PathBuf::from(&state);
-        state_path
-            .parent()
-            .map_or_else(|| PathBuf::from(state), |p| p.join("harness"))
-    };
-    base.join("mcp-loose-ends")
+    hive_sh4re::paths::mcp_loose_ends_dir()
 }
 
 /// Collect all loose-end summary strings published by external MCP daemons.
diff --git a/hive-bash-mcp/src/paths.rs b/hive-bash-mcp/src/paths.rs
index 178838a1..90714e4b 100644
--- a/hive-bash-mcp/src/paths.rs
+++ b/hive-bash-mcp/src/paths.rs
@@ -20,22 +20,13 @@ pub fn daemon_socket() -> PathBuf {
         .map_or_else(|| PathBuf::from(DEFAULT_DAEMON_SOCKET), PathBuf::from)
 }
 
-/// Base harness directory. Uses `HYPERHIVE_HARNESS_DIR` if set (injected
-/// by the hive-c0re meta flake after the harness/state split); falls
-/// back to a `harness/` sibling of the state dir for pre-split
-/// deployments. Shared by every per-agent harness artifact path below.
+/// Base harness directory. Shared resolution lives in
+/// `hive_sh4re::paths::harness_dir` so the harness + every MCP daemon
+/// agree on the layout. Re-exported here as the base for the per-agent
+/// artifact paths below.
 #[must_use]
 pub fn harness_dir() -> PathBuf {
-    if let Some(p) = std::env::var_os("HYPERHIVE_HARNESS_DIR") {
-        PathBuf::from(p)
-    } else {
-        // Pre-split fallback: derive harness/ as a sibling of state/.
-        let state = std::env::var("HYPERHIVE_STATE_DIR").unwrap_or_default();
-        let state_path = PathBuf::from(&state);
-        state_path
-            .parent()
-            .map_or_else(|| PathBuf::from(state), |p| p.join("harness"))
-    }
+    hive_sh4re::paths::harness_dir()
 }
 
 /// Base directory for task files.
@@ -64,13 +55,9 @@ pub fn hyperhive_socket() -> PathBuf {
 /// Directory where MCP daemons write loose-end summary files for the harness.
 /// Each daemon writes `<name>.json` here; the harness scans the dir in
 /// `get_loose_ends` to surface active work from all MCPs generically.
-///
-/// NOTE: the base-dir resolution logic here is intentionally mirrored in
-/// `hive-ag3nt/src/mcp_loose_ends.rs::loose_ends_dir()`. They can't share
-/// code across crates — keep them in sync if the fallback logic changes.
 #[must_use]
 pub fn mcp_loose_ends_dir() -> PathBuf {
-    harness_dir().join("mcp-loose-ends")
+    hive_sh4re::paths::mcp_loose_ends_dir()
 }
 
 /// Full path for a task's JSON metadata file.
diff --git a/hive-matrix-mcp/Cargo.toml b/hive-matrix-mcp/Cargo.toml
index ef4cfeef..9f74495a 100644
--- a/hive-matrix-mcp/Cargo.toml
+++ b/hive-matrix-mcp/Cargo.toml
@@ -9,6 +9,7 @@ workspace = true
 [dependencies]
 anyhow.workspace = true
 futures-util.workspace = true
+hive-sh4re.workspace = true
 matrix-sdk.workspace = true
 reqwest.workspace = true
 rmcp.workspace = true
diff --git a/hive-matrix-mcp/src/paths.rs b/hive-matrix-mcp/src/paths.rs
index 92918dd9..9993a776 100644
--- a/hive-matrix-mcp/src/paths.rs
+++ b/hive-matrix-mcp/src/paths.rs
@@ -70,20 +70,9 @@ pub fn hyperhive_socket() -> PathBuf {
 /// Directory where MCP daemons write loose-end summary files for the harness.
 /// Each daemon writes `<name>.json` here; the harness scans the dir in
 /// `get_loose_ends` to surface active work from all MCPs generically.
-///
-/// NOTE: the base-dir resolution logic here is intentionally mirrored in
-/// `hive-ag3nt/src/mcp_loose_ends.rs::loose_ends_dir()`. They can't share
-/// code across crates — keep them in sync if the fallback logic changes.
+/// Resolution lives in `hive_sh4re::paths` so the harness + every MCP
+/// daemon agree on the location.
 #[must_use]
 pub fn mcp_loose_ends_dir() -> PathBuf {
-    let base = if let Some(p) = std::env::var_os("HYPERHIVE_HARNESS_DIR") {
-        PathBuf::from(p)
-    } else {
-        let state = std::env::var("HYPERHIVE_STATE_DIR").unwrap_or_default();
-        let state_path = PathBuf::from(&state);
-        state_path
-            .parent()
-            .map_or_else(|| PathBuf::from(state), |p| p.join("harness"))
-    };
-    base.join("mcp-loose-ends")
+    hive_sh4re::paths::mcp_loose_ends_dir()
 }
diff --git a/hive-sh4re/src/lib.rs b/hive-sh4re/src/lib.rs
index 191677bf..7308761e 100644
--- a/hive-sh4re/src/lib.rs
+++ b/hive-sh4re/src/lib.rs
@@ -3,6 +3,7 @@
 use serde::{Deserialize, Serialize};
 
 pub mod assets;
+pub mod paths;
 pub mod priv_proto;
 
 // -----------------------------------------------------------------------------
diff --git a/hive-sh4re/src/paths.rs b/hive-sh4re/src/paths.rs
new file mode 100644
index 00000000..f19b3ef4
--- /dev/null
+++ b/hive-sh4re/src/paths.rs
@@ -0,0 +1,33 @@
+//! Shared in-container filesystem-path resolution.
+//!
+//! Every process that runs inside an agent container - the harness plus
+//! the out-of-process MCP daemons (bash, matrix, ...) - must resolve the
+//! harness directory layout identically. These helpers previously had to
+//! be hand-mirrored across crates (each copy carrying a "keep in sync"
+//! comment) because there was no shared home for them; they live here so
+//! the resolution exists exactly once.
+
+use std::path::PathBuf;
+
+/// Base harness directory for the current agent. Uses `HYPERHIVE_HARNESS_DIR`
+/// if set (injected by the hive-c0re meta flake after the harness/state
+/// split); falls back to a `harness/` sibling of `HYPERHIVE_STATE_DIR` for
+/// pre-split / dev deployments.
+#[must_use]
+pub fn harness_dir() -> PathBuf {
+    if let Some(p) = std::env::var_os("HYPERHIVE_HARNESS_DIR") {
+        return PathBuf::from(p);
+    }
+    let state = std::env::var("HYPERHIVE_STATE_DIR").unwrap_or_default();
+    let state_path = PathBuf::from(&state);
+    state_path
+        .parent()
+        .map_or_else(|| PathBuf::from(state), |p| p.join("harness"))
+}
+
+/// Directory where out-of-process MCP daemons write loose-end summary
+/// files (`<name>.json`) for the harness to scan in `get_loose_ends`.
+#[must_use]
+pub fn mcp_loose_ends_dir() -> PathBuf {
+    harness_dir().join("mcp-loose-ends")
+}