diff --git a/lib/crates/fabro-agent/src/cli.rs b/lib/crates/fabro-agent/src/cli.rs
index c15c48ddb..2e97d76ca 100644
--- a/lib/crates/fabro-agent/src/cli.rs
+++ b/lib/crates/fabro-agent/src/cli.rs
@@ -539,7 +539,6 @@ pub async fn run_with_args_and_client(
                             task,
                             ..
                         } => {
-                            let short_id = &agent_id[..8.min(agent_id.len())];
                             let task_preview = if task.len() > 60 {
                                 &task[..crate::truncation::floor_char_boundary(task, 60)]
                             } else {
@@ -548,7 +547,7 @@ pub async fn run_with_args_and_client(
                             eprintln!(
                                 "  {}",
                                 s.dim.apply_to(format!(
-                                    "\u{25b6} subagent {short_id} spawned (depth={depth}) task={task_preview:?}"
+                                    "\u{25b6} subagent {agent_id} spawned (depth={depth}) task={task_preview:?}"
                                 )),
                             );
                         }
@@ -558,11 +557,10 @@ pub async fn run_with_args_and_client(
                             success,
                             turns_used,
                         } => {
-                            let short_id = &agent_id[..8.min(agent_id.len())];
                             eprintln!(
                                 "  {}",
                                 s.dim.apply_to(format!(
-                                    "\u{25a0} subagent {short_id} completed (depth={depth}, success={success}, turns={turns_used})"
+                                    "\u{25a0} subagent {agent_id} completed (depth={depth}, success={success}, turns={turns_used})"
                                 )),
                             );
                         }
@@ -571,20 +569,18 @@ pub async fn run_with_args_and_client(
                             depth,
                             error,
                         } => {
-                            let short_id = &agent_id[..8.min(agent_id.len())];
                             eprintln!(
                                 "  {}",
                                 s.red.apply_to(format!(
-                                    "\u{2717} subagent {short_id} failed (depth={depth}): {error}"
+                                    "\u{2717} subagent {agent_id} failed (depth={depth}): {error}"
                                 )),
                             );
                         }
                         AgentEvent::SubAgentClosed { agent_id, depth } => {
-                            let short_id = &agent_id[..8.min(agent_id.len())];
                             eprintln!(
                                 "  {}",
                                 s.dim.apply_to(format!(
-                                    "\u{25a0} subagent {short_id} closed (depth={depth})"
+                                    "\u{25a0} subagent {agent_id} closed (depth={depth})"
                                 )),
                             );
                         }
@@ -593,11 +589,10 @@ pub async fn run_with_args_and_client(
                             event: child_event,
                             ..
                         } if verbose => {
-                            let short_id = &agent_id[..8.min(agent_id.len())];
                             eprintln!(
                                 "  {}",
                                 s.dim
-                                    .apply_to(format!("[subagent {short_id}] {child_event:?}")),
+                                    .apply_to(format!("[subagent {agent_id}] {child_event:?}")),
                             );
                         }
                         _ => {}
diff --git a/lib/crates/fabro-agent/src/subagent.rs b/lib/crates/fabro-agent/src/subagent.rs
index b29124be4..a1bfd21a8 100644
--- a/lib/crates/fabro-agent/src/subagent.rs
+++ b/lib/crates/fabro-agent/src/subagent.rs
@@ -64,7 +64,7 @@ impl SubAgentManager {
             )));
         }
 
-        let agent_id = uuid::Uuid::new_v4().to_string();
+        let agent_id = format!("{:08x}", uuid::Uuid::new_v4().as_fields().0);
         let followup_queue = session.followup_queue_handle();
         let cancel_token = session.cancel_token();
 
diff --git a/lib/crates/fabro-cli/src/commands/run_progress.rs b/lib/crates/fabro-cli/src/commands/run_progress.rs
index 8b7a5857a..56c5ef9ef 100644
--- a/lib/crates/fabro-cli/src/commands/run_progress.rs
+++ b/lib/crates/fabro-cli/src/commands/run_progress.rs
@@ -1419,11 +1419,10 @@ impl ProgressUI {
             }
             AgentEvent::SubAgentSpawned { agent_id, task, .. } if self.verbose => {
                 let dim = Style::new().dim();
-                let short_id = &agent_id[..agent_id.len().min(8)];
                 self.insert_subagent_line_for_stage(
                     stage_node_id,
                     &dim.apply_to(format!(
-                        "\u{25b8} subagent[{short_id}] \"{}\"",
+                        "\u{25b8} subagent[{agent_id}] \"{}\"",
                         truncate(task, 50)
                     ))
                     .to_string(),
@@ -1435,11 +1434,10 @@ impl ProgressUI {
                 success,
                 ..
             } if self.verbose => {
-                let short_id = &agent_id[..agent_id.len().min(8)];
                 let glyph = if *success { green_check() } else { red_cross() };
                 self.insert_subagent_line_for_stage(
                     stage_node_id,
-                    &format!("{glyph} subagent[{short_id}] ({turns_used} turns)"),
+                    &format!("{glyph} subagent[{agent_id}] ({turns_used} turns)"),
                 );
             }
             _ => {}
diff --git a/plan.md b/plan.md
new file mode 100644
index 000000000..45c8811ee
--- /dev/null
+++ b/plan.md
@@ -0,0 +1,71 @@
+# Plan: Use short hex IDs for subagents instead of UUIDs
+
+## Summary
+
+GitHub issue #126: Subagent IDs are currently full UUID v4 strings (36 chars, e.g. `550e8400-e29b-41d4-a716-446655440000`). These are verbose in CLI output and error-prone when referenced by the LLM in tools like `send_input`, `wait`, and `close_agent`. The codebase already truncates agent IDs to 8 chars for display in multiple places. This change replaces UUID generation with a random 8-char hex string (e.g. `a3f1b20c`) so the full ID matches what's already displayed.
+
+## Files to modify
+
+### 1. `lib/crates/fabro-agent/Cargo.toml`
+- Add `rand.workspace = true` to `[dependencies]`. (`rand = "0.8"` is already defined in workspace root `Cargo.toml`; other crates like `fabro-cli`, `fabro-llm`, `fabro-workflows` already use it.)
+- Do **not** remove `uuid.workspace = true` — it's still used in `session.rs:58` for session IDs.
+
+### 2. `lib/crates/fabro-agent/src/subagent.rs`
+- **Line 67**: Replace `uuid::Uuid::new_v4().to_string()` with `format!("{:08x}", rand::random::<u32>())`.
+- This generates 8-char lowercase hex strings with ~4 billion possible values — collision-free within a session.
+
+### 3. `lib/crates/fabro-agent/src/cli.rs`
+Remove the `short_id` truncation pattern in 5 places. Since IDs are now 8 chars, `short_id == agent_id`, so use `agent_id` directly:
+
+- **Line 542** (`SubAgentSpawned` handler): Remove `let short_id = &agent_id[..8.min(agent_id.len())];` and replace `{short_id}` with `{agent_id}` in the format string.
+- **Line 561** (`SubAgentCompleted` handler): Same removal and replacement.
+- **Line 574** (`SubAgentFailed` handler): Same removal and replacement.
+- **Line 583** (`SubAgentClosed` handler): Same removal and replacement.
+- **Line 596** (`SubAgentEvent` handler, verbose mode): Same removal and replacement.
+
+### 4. `lib/crates/fabro-cli/src/commands/run_progress.rs`
+Remove the `short_id` truncation pattern in 2 places:
+
+- **Line 1416** (`SubAgentSpawned` handler): Remove `let short_id = &agent_id[..agent_id.len().min(8)];` and replace `{short_id}` with `{agent_id}` in the format string.
+- **Line 1432** (`SubAgentCompleted` handler): Same removal and replacement.
+
+## Step-by-step implementation
+
+1. **Add `rand` dependency to `fabro-agent`**:
+   In `lib/crates/fabro-agent/Cargo.toml`, add `rand.workspace = true` to the `[dependencies]` section (e.g. after the `uuid.workspace = true` line).
+
+2. **Replace UUID generation in `subagent.rs`**:
+   In `lib/crates/fabro-agent/src/subagent.rs` line 67, change:
+   ```rust
+   let agent_id = uuid::Uuid::new_v4().to_string();
+   ```
+   to:
+   ```rust
+   let agent_id = format!("{:08x}", rand::random::<u32>());
+   ```
+
+3. **Remove `short_id` truncation in `cli.rs`**:
+   In `lib/crates/fabro-agent/src/cli.rs`, for each of the 5 occurrences of `let short_id = &agent_id[..8.min(agent_id.len())];` (lines 542, 561, 574, 583, 596):
+   - Delete the `let short_id = ...` line.
+   - Replace `{short_id}` with `{agent_id}` in the corresponding format string on the same match arm.
+
+4. **Remove `short_id` truncation in `run_progress.rs`**:
+   In `lib/crates/fabro-cli/src/commands/run_progress.rs`, for each of the 2 occurrences of `let short_id = &agent_id[..agent_id.len().min(8)];` (lines 1416, 1432):
+   - Delete the `let short_id = ...` line.
+   - Replace `{short_id}` with `{agent_id}` in the corresponding format string.
+
+## Verification
+
+- `cargo build --workspace` — clean build with no errors.
+- `cargo test -p fabro-agent` — all existing subagent tests pass. Tests use hardcoded IDs like `"sa-1"`, not UUIDs, so no test changes needed.
+- `cargo clippy --workspace -- -D warnings` — no new warnings.
+- `cargo fmt --check --all` — formatting is clean.
+
+## Test cases
+
+No new test cases are needed. The existing tests in `subagent.rs` (e.g. `spawn_creates_agent_and_returns_id`) already verify that:
+- `agent_id` is non-empty
+- The agent can be looked up by its ID
+- Spawn/wait/close/send_input work with the generated IDs
+
+The generated IDs will now be 8 chars instead of 36, but the tests don't assert on length or format, so they pass unchanged.