diff --git a/crates/app_operation_system/src/handler.rs b/crates/app_operation_system/src/handler.rs
index dc16bd5..524b6cc 100644
--- a/crates/app_operation_system/src/handler.rs
+++ b/crates/app_operation_system/src/handler.rs
@@ -1 +1,3 @@
 pub mod doc;
+pub mod segment;
+pub mod station;
diff --git a/crates/app_operation_system/src/handler/segment.rs b/crates/app_operation_system/src/handler/segment.rs
new file mode 100644
index 0000000..af66783
--- /dev/null
+++ b/crates/app_operation_system/src/handler/segment.rs
@@ -0,0 +1,595 @@
+use axum::{
+    extract::{Path, Query, State},
+    http::StatusCode,
+    response::IntoResponse,
+    Json,
+};
+use serde::Deserialize;
+use serde_json::json;
+use uuid::Uuid;
+use validator::Validate;
+
+use plc_platform_core::util::response::ApiErr;
+
+use crate::{
+    service::segment as segment_service,
+    AppState,
+};
+
+const SEGMENT_TYPES: &[&str] = &[
+    "front_load",
+    "robot",
+    "front_release",
+    "front_transfer",
+    "kiln_infeed",
+    "kiln_step",
+    "kiln_outfeed",
+    "tail_transfer",
+    "tail_step",
+    "unload",
+    "return",
+];
+
+const SEGMENT_MODES: &[&str] = &["auto", "remote_manual", "local_manual", "disabled"];
+
+const ACTION_KINDS: &[&str] = &[
+    "open_door",
+    "close_door",
+    "push_forward",
+    "push_retract",
+    "pull_run",
+    "pull_retract",
+    "transfer_move_to",
+    "step_once",
+    "robot_permit",
+    "robot_release",
+    "wait_signal",
+    "pulse_cmd",
+];
+
+const ON_TIMEOUT_VALUES: &[&str] = &["fault", "retry", "block"];
+
+const INTERLOCK_APPLIES_TO: &[&str] = &["start_allow", "start_deny", "run_halt"];
+
+const RULE_KINDS: &[&str] = &[
+    "point_eq",
+    "station_vacant",
+    "station_occupied",
+    "equipment_origin",
+    "equipment_no_fault",
+    "equipment_remote",
+    "safety_chain_ok",
+];
+
+fn validate_enum(name: &'static str, value: &str, allowed: &[&str]) -> Result<(), ApiErr> {
+    if allowed.contains(&value) {
+        Ok(())
+    } else {
+        Err(ApiErr::BadRequest(
+            format!("invalid {}: {}", name, value),
+            Some(json!({ "allowed": allowed })),
+        ))
+    }
+}
+
+#[derive(Debug, Deserialize, Validate)]
+pub struct ListSegmentQuery {
+    #[validate(length(min = 1, max = 50))]
+    pub line_code: Option<String>,
+}
+
+pub async fn list_segments(
+    State(state): State<AppState>,
+    Query(query): Query<ListSegmentQuery>,
+) -> Result<impl IntoResponse, ApiErr> {
+    query.validate()?;
+    let segments =
+        segment_service::list_segments(&state.platform.pool, query.line_code.as_deref()).await?;
+    Ok(Json(segments))
+}
+
+pub async fn get_segment(
+    State(state): State<AppState>,
+    Path(segment_id): Path<Uuid>,
+) -> Result<impl IntoResponse, ApiErr> {
+    let segment = segment_service::get_segment_by_id(&state.platform.pool, segment_id)
+        .await?
+        .ok_or_else(|| ApiErr::NotFound("Segment not found".to_string(), None))?;
+    Ok(Json(segment))
+}
+
+pub async fn get_segment_detail(
+    State(state): State<AppState>,
+    Path(segment_id): Path<Uuid>,
+) -> Result<impl IntoResponse, ApiErr> {
+    let segment = segment_service::get_segment_by_id(&state.platform.pool, segment_id)
+        .await?
+        .ok_or_else(|| ApiErr::NotFound("Segment not found".to_string(), None))?;
+    let steps = segment_service::list_steps(&state.platform.pool, segment_id).await?;
+    let interlocks =
+        segment_service::list_interlocks(&state.platform.pool, segment_id).await?;
+    let resources =
+        segment_service::list_resources(&state.platform.pool, segment_id).await?;
+
+    Ok(Json(json!({
+        "segment": segment,
+        "steps": steps,
+        "interlocks": interlocks,
+        "resources": resources,
+    })))
+}
+
+#[derive(Debug, Deserialize, Validate)]
+pub struct CreateSegmentReq {
+    #[validate(length(min = 1, max = 100))]
+    pub code: String,
+    #[validate(length(min = 1, max = 100))]
+    pub name: String,
+    #[validate(length(min = 1, max = 32))]
+    pub segment_type: String,
+    #[validate(length(min = 1, max = 50))]
+    pub line_code: Option<String>,
+    pub priority: Option<i32>,
+    pub enabled: Option<bool>,
+    #[validate(length(min = 1, max = 32))]
+    pub mode: Option<String>,
+    pub require_manual_ack_after_fault: Option<bool>,
+    pub description: Option<String>,
+}
+
+pub async fn create_segment(
+    State(state): State<AppState>,
+    Json(payload): Json<CreateSegmentReq>,
+) -> Result<impl IntoResponse, ApiErr> {
+    payload.validate()?;
+    validate_enum("segment_type", &payload.segment_type, SEGMENT_TYPES)?;
+    let mode = payload.mode.as_deref().unwrap_or("disabled");
+    validate_enum("mode", mode, SEGMENT_MODES)?;
+
+    if segment_service::get_segment_by_code(&state.platform.pool, &payload.code)
+        .await?
+        .is_some()
+    {
+        return Err(ApiErr::BadRequest(
+            "Segment code already exists".to_string(),
+            None,
+        ));
+    }
+
+    let segment_id = segment_service::create_segment(
+        &state.platform.pool,
+        segment_service::CreateSegmentParams {
+            code: &payload.code,
+            name: &payload.name,
+            segment_type: &payload.segment_type,
+            line_code: payload.line_code.as_deref(),
+            priority: payload.priority.unwrap_or(0),
+            enabled: payload.enabled.unwrap_or(true),
+            mode,
+            require_manual_ack_after_fault: payload.require_manual_ack_after_fault.unwrap_or(true),
+            description: payload.description.as_deref(),
+        },
+    )
+    .await?;
+
+    Ok((
+        StatusCode::CREATED,
+        Json(json!({ "id": segment_id, "ok_msg": "Segment created" })),
+    ))
+}
+
+#[derive(Debug, Deserialize, Validate)]
+pub struct UpdateSegmentReq {
+    #[validate(length(min = 1, max = 100))]
+    pub code: Option<String>,
+    #[validate(length(min = 1, max = 100))]
+    pub name: Option<String>,
+    #[validate(length(min = 1, max = 32))]
+    pub segment_type: Option<String>,
+    #[validate(length(min = 1, max = 50))]
+    pub line_code: Option<String>,
+    pub priority: Option<i32>,
+    pub enabled: Option<bool>,
+    #[validate(length(min = 1, max = 32))]
+    pub mode: Option<String>,
+    pub require_manual_ack_after_fault: Option<bool>,
+    pub description: Option<String>,
+}
+
+pub async fn update_segment(
+    State(state): State<AppState>,
+    Path(segment_id): Path<Uuid>,
+    Json(payload): Json<UpdateSegmentReq>,
+) -> Result<impl IntoResponse, ApiErr> {
+    payload.validate()?;
+    if let Some(s) = payload.segment_type.as_deref() {
+        validate_enum("segment_type", s, SEGMENT_TYPES)?;
+    }
+    if let Some(m) = payload.mode.as_deref() {
+        validate_enum("mode", m, SEGMENT_MODES)?;
+    }
+
+    let existing = segment_service::get_segment_by_id(&state.platform.pool, segment_id)
+        .await?
+        .ok_or_else(|| ApiErr::NotFound("Segment not found".to_string(), None))?;
+
+    if let Some(code) = payload.code.as_deref() {
+        if let Some(other) =
+            segment_service::get_segment_by_code(&state.platform.pool, code).await?
+        {
+            if other.id != existing.id {
+                return Err(ApiErr::BadRequest(
+                    "Segment code already exists".to_string(),
+                    None,
+                ));
+            }
+        }
+    }
+
+    segment_service::update_segment(
+        &state.platform.pool,
+        segment_id,
+        segment_service::UpdateSegmentParams {
+            code: payload.code.as_deref(),
+            name: payload.name.as_deref(),
+            segment_type: payload.segment_type.as_deref(),
+            line_code: payload.line_code.as_deref(),
+            priority: payload.priority,
+            enabled: payload.enabled,
+            mode: payload.mode.as_deref(),
+            require_manual_ack_after_fault: payload.require_manual_ack_after_fault,
+            description: payload.description.as_deref(),
+        },
+    )
+    .await?;
+
+    Ok(Json(json!({ "ok_msg": "Segment updated" })))
+}
+
+pub async fn delete_segment(
+    State(state): State<AppState>,
+    Path(segment_id): Path<Uuid>,
+) -> Result<impl IntoResponse, ApiErr> {
+    let deleted = segment_service::delete_segment(&state.platform.pool, segment_id).await?;
+    if !deleted {
+        return Err(ApiErr::NotFound("Segment not found".to_string(), None));
+    }
+    Ok(StatusCode::NO_CONTENT)
+}
+
+// Steps
+
+pub async fn list_steps(
+    State(state): State<AppState>,
+    Path(segment_id): Path<Uuid>,
+) -> Result<impl IntoResponse, ApiErr> {
+    let steps = segment_service::list_steps(&state.platform.pool, segment_id).await?;
+    Ok(Json(steps))
+}
+
+#[derive(Debug, Deserialize, Validate)]
+pub struct CreateStepReq {
+    #[validate(range(min = 1))]
+    pub step_no: i32,
+    #[validate(length(min = 1, max = 64))]
+    pub step_code: String,
+    #[validate(length(min = 1, max = 32))]
+    pub action_kind: String,
+    pub target_equipment_id: Option<Uuid>,
+    pub target_station_id: Option<Uuid>,
+    #[validate(length(min = 1, max = 32))]
+    pub confirm_signal_role: Option<String>,
+    pub confirm_point_id: Option<Uuid>,
+    pub expected_value: Option<bool>,
+    #[validate(range(min = 1))]
+    pub timeout_ms: Option<i32>,
+    #[validate(length(min = 1, max = 32))]
+    pub command_role: Option<String>,
+    #[validate(length(min = 1, max = 32))]
+    pub stop_command_role: Option<String>,
+    #[validate(range(min = 1))]
+    pub pulse_ms: Option<i32>,
+    pub hold_until_confirm: Option<bool>,
+    pub cancel_on_fault: Option<bool>,
+    pub next_step_no_on_success: Option<i32>,
+    pub next_step_no_on_failure: Option<i32>,
+    #[validate(length(min = 1, max = 16))]
+    pub on_timeout: Option<String>,
+    pub description: Option<String>,
+}
+
+pub async fn create_step(
+    State(state): State<AppState>,
+    Path(segment_id): Path<Uuid>,
+    Json(payload): Json<CreateStepReq>,
+) -> Result<impl IntoResponse, ApiErr> {
+    payload.validate()?;
+    validate_enum("action_kind", &payload.action_kind, ACTION_KINDS)?;
+    let on_timeout = payload.on_timeout.as_deref().unwrap_or("fault");
+    validate_enum("on_timeout", on_timeout, ON_TIMEOUT_VALUES)?;
+
+    segment_service::get_segment_by_id(&state.platform.pool, segment_id)
+        .await?
+        .ok_or_else(|| ApiErr::NotFound("Segment not found".to_string(), None))?;
+
+    let step_id = segment_service::create_step(
+        &state.platform.pool,
+        segment_service::CreateStepParams {
+            segment_id,
+            step_no: payload.step_no,
+            step_code: &payload.step_code,
+            action_kind: &payload.action_kind,
+            target_equipment_id: payload.target_equipment_id,
+            target_station_id: payload.target_station_id,
+            confirm_signal_role: payload.confirm_signal_role.as_deref(),
+            confirm_point_id: payload.confirm_point_id,
+            expected_value: payload.expected_value.unwrap_or(true),
+            timeout_ms: payload.timeout_ms.unwrap_or(30000),
+            command_role: payload.command_role.as_deref(),
+            stop_command_role: payload.stop_command_role.as_deref(),
+            pulse_ms: payload.pulse_ms,
+            hold_until_confirm: payload.hold_until_confirm.unwrap_or(false),
+            cancel_on_fault: payload.cancel_on_fault.unwrap_or(true),
+            next_step_no_on_success: payload.next_step_no_on_success,
+            next_step_no_on_failure: payload.next_step_no_on_failure,
+            on_timeout,
+            description: payload.description.as_deref(),
+        },
+    )
+    .await?;
+
+    Ok((
+        StatusCode::CREATED,
+        Json(json!({ "id": step_id, "ok_msg": "Step created" })),
+    ))
+}
+
+#[derive(Debug, Deserialize, Validate)]
+pub struct UpdateStepReq {
+    #[validate(length(min = 1, max = 64))]
+    pub step_code: Option<String>,
+    #[validate(length(min = 1, max = 32))]
+    pub action_kind: Option<String>,
+    pub target_equipment_id: Option<Uuid>,
+    pub target_station_id: Option<Uuid>,
+    #[validate(length(min = 1, max = 32))]
+    pub confirm_signal_role: Option<String>,
+    pub confirm_point_id: Option<Uuid>,
+    pub expected_value: Option<bool>,
+    #[validate(range(min = 1))]
+    pub timeout_ms: Option<i32>,
+    #[validate(length(min = 1, max = 32))]
+    pub command_role: Option<String>,
+    #[validate(length(min = 1, max = 32))]
+    pub stop_command_role: Option<String>,
+    #[validate(range(min = 1))]
+    pub pulse_ms: Option<i32>,
+    pub hold_until_confirm: Option<bool>,
+    pub cancel_on_fault: Option<bool>,
+    pub next_step_no_on_success: Option<i32>,
+    pub next_step_no_on_failure: Option<i32>,
+    #[validate(length(min = 1, max = 16))]
+    pub on_timeout: Option<String>,
+    pub description: Option<String>,
+}
+
+pub async fn update_step(
+    State(state): State<AppState>,
+    Path((segment_id, step_no)): Path<(Uuid, i32)>,
+    Json(payload): Json<UpdateStepReq>,
+) -> Result<impl IntoResponse, ApiErr> {
+    payload.validate()?;
+    if let Some(a) = payload.action_kind.as_deref() {
+        validate_enum("action_kind", a, ACTION_KINDS)?;
+    }
+    if let Some(t) = payload.on_timeout.as_deref() {
+        validate_enum("on_timeout", t, ON_TIMEOUT_VALUES)?;
+    }
+
+    segment_service::get_step(&state.platform.pool, segment_id, step_no)
+        .await?
+        .ok_or_else(|| ApiErr::NotFound("Step not found".to_string(), None))?;
+
+    segment_service::update_step(
+        &state.platform.pool,
+        segment_id,
+        step_no,
+        segment_service::UpdateStepParams {
+            step_code: payload.step_code.as_deref(),
+            action_kind: payload.action_kind.as_deref(),
+            target_equipment_id: payload.target_equipment_id,
+            target_station_id: payload.target_station_id,
+            confirm_signal_role: payload.confirm_signal_role.as_deref(),
+            confirm_point_id: payload.confirm_point_id,
+            expected_value: payload.expected_value,
+            timeout_ms: payload.timeout_ms,
+            command_role: payload.command_role.as_deref(),
+            stop_command_role: payload.stop_command_role.as_deref(),
+            pulse_ms: payload.pulse_ms,
+            hold_until_confirm: payload.hold_until_confirm,
+            cancel_on_fault: payload.cancel_on_fault,
+            next_step_no_on_success: payload.next_step_no_on_success,
+            next_step_no_on_failure: payload.next_step_no_on_failure,
+            on_timeout: payload.on_timeout.as_deref(),
+            description: payload.description.as_deref(),
+        },
+    )
+    .await?;
+
+    Ok(Json(json!({ "ok_msg": "Step updated" })))
+}
+
+pub async fn delete_step(
+    State(state): State<AppState>,
+    Path((segment_id, step_no)): Path<(Uuid, i32)>,
+) -> Result<impl IntoResponse, ApiErr> {
+    let deleted = segment_service::delete_step(&state.platform.pool, segment_id, step_no).await?;
+    if !deleted {
+        return Err(ApiErr::NotFound("Step not found".to_string(), None));
+    }
+    Ok(StatusCode::NO_CONTENT)
+}
+
+// Interlocks
+
+pub async fn list_interlocks(
+    State(state): State<AppState>,
+    Path(segment_id): Path<Uuid>,
+) -> Result<impl IntoResponse, ApiErr> {
+    let interlocks =
+        segment_service::list_interlocks(&state.platform.pool, segment_id).await?;
+    Ok(Json(interlocks))
+}
+
+#[derive(Debug, Deserialize, Validate)]
+pub struct CreateInterlockReq {
+    #[validate(length(min = 1, max = 32))]
+    pub applies_to: String,
+    #[validate(length(min = 1, max = 32))]
+    pub rule_kind: String,
+    pub point_id: Option<Uuid>,
+    pub station_id: Option<Uuid>,
+    pub equipment_id: Option<Uuid>,
+    pub expected_value: Option<bool>,
+    pub description: Option<String>,
+}
+
+pub async fn create_interlock(
+    State(state): State<AppState>,
+    Path(segment_id): Path<Uuid>,
+    Json(payload): Json<CreateInterlockReq>,
+) -> Result<impl IntoResponse, ApiErr> {
+    payload.validate()?;
+    validate_enum("applies_to", &payload.applies_to, INTERLOCK_APPLIES_TO)?;
+    validate_enum("rule_kind", &payload.rule_kind, RULE_KINDS)?;
+
+    segment_service::get_segment_by_id(&state.platform.pool, segment_id)
+        .await?
+        .ok_or_else(|| ApiErr::NotFound("Segment not found".to_string(), None))?;
+
+    let interlock_id = segment_service::create_interlock(
+        &state.platform.pool,
+        segment_service::CreateInterlockParams {
+            segment_id,
+            applies_to: &payload.applies_to,
+            rule_kind: &payload.rule_kind,
+            point_id: payload.point_id,
+            station_id: payload.station_id,
+            equipment_id: payload.equipment_id,
+            expected_value: payload.expected_value,
+            description: payload.description.as_deref(),
+        },
+    )
+    .await?;
+
+    Ok((
+        StatusCode::CREATED,
+        Json(json!({ "id": interlock_id, "ok_msg": "Interlock created" })),
+    ))
+}
+
+pub async fn delete_interlock(
+    State(state): State<AppState>,
+    Path((segment_id, interlock_id)): Path<(Uuid, Uuid)>,
+) -> Result<impl IntoResponse, ApiErr> {
+    let deleted =
+        segment_service::delete_interlock(&state.platform.pool, segment_id, interlock_id).await?;
+    if !deleted {
+        return Err(ApiErr::NotFound("Interlock not found".to_string(), None));
+    }
+    Ok(StatusCode::NO_CONTENT)
+}
+
+// Resources (declared keys for a segment)
+
+pub async fn list_resources(
+    State(state): State<AppState>,
+    Path(segment_id): Path<Uuid>,
+) -> Result<impl IntoResponse, ApiErr> {
+    let resources =
+        segment_service::list_resources(&state.platform.pool, segment_id).await?;
+    Ok(Json(resources))
+}
+
+#[derive(Debug, Deserialize, Validate)]
+pub struct ReplaceResourcesReq {
+    pub resource_keys: Vec<String>,
+}
+
+pub async fn replace_resources(
+    State(state): State<AppState>,
+    Path(segment_id): Path<Uuid>,
+    Json(payload): Json<ReplaceResourcesReq>,
+) -> Result<impl IntoResponse, ApiErr> {
+    for key in &payload.resource_keys {
+        if key.is_empty() || key.len() > 64 {
+            return Err(ApiErr::BadRequest(
+                "resource_key must be 1..=64 chars".to_string(),
+                Some(json!({ "key": key })),
+            ));
+        }
+    }
+
+    segment_service::get_segment_by_id(&state.platform.pool, segment_id)
+        .await?
+        .ok_or_else(|| ApiErr::NotFound("Segment not found".to_string(), None))?;
+
+    segment_service::replace_resources(&state.platform.pool, segment_id, &payload.resource_keys)
+        .await?;
+
+    Ok(Json(
+        json!({ "ok_msg": "Resources replaced", "count": payload.resource_keys.len() }),
+    ))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn validate_enum_rejects_unknown() {
+        assert!(validate_enum("mode", "weird", SEGMENT_MODES).is_err());
+        assert!(validate_enum("mode", "auto", SEGMENT_MODES).is_ok());
+    }
+
+    #[test]
+    fn create_segment_req_rejects_blank_code() {
+        let payload = CreateSegmentReq {
+            code: "".to_string(),
+            name: "Dry-1 infeed".to_string(),
+            segment_type: "kiln_infeed".to_string(),
+            line_code: None,
+            priority: None,
+            enabled: None,
+            mode: None,
+            require_manual_ack_after_fault: None,
+            description: None,
+        };
+        assert!(payload.validate().is_err());
+    }
+
+    #[test]
+    fn create_step_req_rejects_zero_step_no() {
+        let payload = CreateStepReq {
+            step_no: 0,
+            step_code: "S1".to_string(),
+            action_kind: "open_door".to_string(),
+            target_equipment_id: None,
+            target_station_id: None,
+            confirm_signal_role: None,
+            confirm_point_id: None,
+            expected_value: None,
+            timeout_ms: None,
+            command_role: None,
+            stop_command_role: None,
+            pulse_ms: None,
+            hold_until_confirm: None,
+            cancel_on_fault: None,
+            next_step_no_on_success: None,
+            next_step_no_on_failure: None,
+            on_timeout: None,
+            description: None,
+        };
+        assert!(payload.validate().is_err());
+    }
+}
diff --git a/crates/app_operation_system/src/handler/station.rs b/crates/app_operation_system/src/handler/station.rs
new file mode 100644
index 0000000..bdf201a
--- /dev/null
+++ b/crates/app_operation_system/src/handler/station.rs
@@ -0,0 +1,317 @@
+use axum::{
+    extract::{Path, Query, State},
+    http::StatusCode,
+    response::IntoResponse,
+    Json,
+};
+use serde::Deserialize;
+use serde_json::json;
+use uuid::Uuid;
+use validator::Validate;
+
+use plc_platform_core::util::response::ApiErr;
+
+use crate::{service::station as station_service, AppState};
+
+const STATION_TYPES: &[&str] = &[
+    "load",
+    "dry_in",
+    "dry_step",
+    "dry_out",
+    "fire_in",
+    "fire_step",
+    "fire_out",
+    "transfer",
+    "unload",
+    "return",
+];
+
+const SIGNAL_ROLES: &[&str] = &[
+    "presence",
+    "vacancy",
+    "arrived",
+    "allow_in",
+    "done",
+    "fault",
+];
+
+fn validate_station_type(value: &str) -> Result<(), ApiErr> {
+    if STATION_TYPES.contains(&value) {
+        Ok(())
+    } else {
+        Err(ApiErr::BadRequest(
+            format!("invalid station_type: {}", value),
+            Some(json!({ "allowed": STATION_TYPES })),
+        ))
+    }
+}
+
+fn validate_signal_role(value: &str) -> Result<(), ApiErr> {
+    if SIGNAL_ROLES.contains(&value) {
+        Ok(())
+    } else {
+        Err(ApiErr::BadRequest(
+            format!("invalid signal_role: {}", value),
+            Some(json!({ "allowed": SIGNAL_ROLES })),
+        ))
+    }
+}
+
+#[derive(Debug, Deserialize, Validate)]
+pub struct ListStationQuery {
+    #[validate(length(min = 1, max = 50))]
+    pub line_code: Option<String>,
+}
+
+pub async fn list_stations(
+    State(state): State<AppState>,
+    Query(query): Query<ListStationQuery>,
+) -> Result<impl IntoResponse, ApiErr> {
+    query.validate()?;
+    let stations =
+        station_service::list_stations(&state.platform.pool, query.line_code.as_deref()).await?;
+    Ok(Json(stations))
+}
+
+pub async fn get_station(
+    State(state): State<AppState>,
+    Path(station_id): Path<Uuid>,
+) -> Result<impl IntoResponse, ApiErr> {
+    let station = station_service::get_station_by_id(&state.platform.pool, station_id)
+        .await?
+        .ok_or_else(|| ApiErr::NotFound("Station not found".to_string(), None))?;
+    let signals =
+        station_service::list_station_signals(&state.platform.pool, station_id).await?;
+    Ok(Json(json!({
+        "station": station,
+        "signals": signals,
+    })))
+}
+
+#[derive(Debug, Deserialize, Validate)]
+pub struct CreateStationReq {
+    #[validate(length(min = 1, max = 100))]
+    pub code: String,
+    #[validate(length(min = 1, max = 100))]
+    pub name: String,
+    #[validate(length(min = 1, max = 50))]
+    pub line_code: Option<String>,
+    #[validate(length(min = 1, max = 50))]
+    pub segment_code: Option<String>,
+    #[validate(length(min = 1, max = 32))]
+    pub station_type: String,
+    pub enabled: Option<bool>,
+    pub description: Option<String>,
+}
+
+pub async fn create_station(
+    State(state): State<AppState>,
+    Json(payload): Json<CreateStationReq>,
+) -> Result<impl IntoResponse, ApiErr> {
+    payload.validate()?;
+    validate_station_type(&payload.station_type)?;
+
+    if station_service::get_station_by_code(&state.platform.pool, &payload.code)
+        .await?
+        .is_some()
+    {
+        return Err(ApiErr::BadRequest(
+            "Station code already exists".to_string(),
+            None,
+        ));
+    }
+
+    let station_id = station_service::create_station(
+        &state.platform.pool,
+        station_service::CreateStationParams {
+            code: &payload.code,
+            name: &payload.name,
+            line_code: payload.line_code.as_deref(),
+            segment_code: payload.segment_code.as_deref(),
+            station_type: &payload.station_type,
+            enabled: payload.enabled.unwrap_or(true),
+            description: payload.description.as_deref(),
+        },
+    )
+    .await?;
+
+    Ok((
+        StatusCode::CREATED,
+        Json(json!({ "id": station_id, "ok_msg": "Station created" })),
+    ))
+}
+
+#[derive(Debug, Deserialize, Validate)]
+pub struct UpdateStationReq {
+    #[validate(length(min = 1, max = 100))]
+    pub code: Option<String>,
+    #[validate(length(min = 1, max = 100))]
+    pub name: Option<String>,
+    #[validate(length(min = 1, max = 50))]
+    pub line_code: Option<String>,
+    #[validate(length(min = 1, max = 50))]
+    pub segment_code: Option<String>,
+    #[validate(length(min = 1, max = 32))]
+    pub station_type: Option<String>,
+    pub enabled: Option<bool>,
+    pub description: Option<String>,
+}
+
+pub async fn update_station(
+    State(state): State<AppState>,
+    Path(station_id): Path<Uuid>,
+    Json(payload): Json<UpdateStationReq>,
+) -> Result<impl IntoResponse, ApiErr> {
+    payload.validate()?;
+    if let Some(t) = payload.station_type.as_deref() {
+        validate_station_type(t)?;
+    }
+
+    let existing = station_service::get_station_by_id(&state.platform.pool, station_id)
+        .await?
+        .ok_or_else(|| ApiErr::NotFound("Station not found".to_string(), None))?;
+
+    if let Some(code) = payload.code.as_deref() {
+        if let Some(other) =
+            station_service::get_station_by_code(&state.platform.pool, code).await?
+        {
+            if other.id != existing.id {
+                return Err(ApiErr::BadRequest(
+                    "Station code already exists".to_string(),
+                    None,
+                ));
+            }
+        }
+    }
+
+    station_service::update_station(
+        &state.platform.pool,
+        station_id,
+        station_service::UpdateStationParams {
+            code: payload.code.as_deref(),
+            name: payload.name.as_deref(),
+            line_code: payload.line_code.as_deref(),
+            segment_code: payload.segment_code.as_deref(),
+            station_type: payload.station_type.as_deref(),
+            enabled: payload.enabled,
+            description: payload.description.as_deref(),
+        },
+    )
+    .await?;
+
+    Ok(Json(json!({ "ok_msg": "Station updated" })))
+}
+
+pub async fn delete_station(
+    State(state): State<AppState>,
+    Path(station_id): Path<Uuid>,
+) -> Result<impl IntoResponse, ApiErr> {
+    let deleted = station_service::delete_station(&state.platform.pool, station_id).await?;
+    if !deleted {
+        return Err(ApiErr::NotFound("Station not found".to_string(), None));
+    }
+    Ok(StatusCode::NO_CONTENT)
+}
+
+#[derive(Debug, Deserialize, Validate)]
+pub struct UpsertStationSignalReq {
+    #[validate(length(min = 1, max = 32))]
+    pub signal_role: String,
+    pub point_id: Option<Uuid>,
+    #[validate(length(min = 1, max = 32))]
+    pub derived_from_role: Option<String>,
+    pub invert_value: Option<bool>,
+}
+
+pub async fn upsert_station_signal(
+    State(state): State<AppState>,
+    Path(station_id): Path<Uuid>,
+    Json(payload): Json<UpsertStationSignalReq>,
+) -> Result<impl IntoResponse, ApiErr> {
+    payload.validate()?;
+    validate_signal_role(&payload.signal_role)?;
+    if let Some(role) = payload.derived_from_role.as_deref() {
+        validate_signal_role(role)?;
+    }
+    if payload.point_id.is_none() && payload.derived_from_role.is_none() {
+        return Err(ApiErr::BadRequest(
+            "either point_id or derived_from_role must be provided".to_string(),
+            None,
+        ));
+    }
+
+    station_service::get_station_by_id(&state.platform.pool, station_id)
+        .await?
+        .ok_or_else(|| ApiErr::NotFound("Station not found".to_string(), None))?;
+
+    let signal = station_service::upsert_station_signal(
+        &state.platform.pool,
+        station_id,
+        station_service::UpsertStationSignalParams {
+            signal_role: payload.signal_role,
+            point_id: payload.point_id,
+            derived_from_role: payload.derived_from_role,
+            invert_value: payload.invert_value.unwrap_or(false),
+        },
+    )
+    .await?;
+
+    Ok(Json(signal))
+}
+
+pub async fn delete_station_signal(
+    State(state): State<AppState>,
+    Path((station_id, role)): Path<(Uuid, String)>,
+) -> Result<impl IntoResponse, ApiErr> {
+    validate_signal_role(&role)?;
+    let deleted =
+        station_service::delete_station_signal(&state.platform.pool, station_id, &role).await?;
+    if !deleted {
+        return Err(ApiErr::NotFound(
+            "Station signal binding not found".to_string(),
+            None,
+        ));
+    }
+    Ok(StatusCode::NO_CONTENT)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::model::StationSignalRole;
+
+    #[test]
+    fn create_station_req_rejects_blank_code() {
+        let payload = CreateStationReq {
+            code: "".to_string(),
+            name: "Dry-1 In".to_string(),
+            line_code: None,
+            segment_code: None,
+            station_type: "dry_in".to_string(),
+            enabled: None,
+            description: None,
+        };
+        assert!(payload.validate().is_err());
+    }
+
+    #[test]
+    fn validate_station_type_rejects_unknown() {
+        assert!(validate_station_type("nope").is_err());
+        assert!(validate_station_type("dry_in").is_ok());
+    }
+
+    #[test]
+    fn station_signal_role_enum_covers_handler_allowlist() {
+        let known = [
+            StationSignalRole::Presence,
+            StationSignalRole::Vacancy,
+            StationSignalRole::Arrived,
+            StationSignalRole::AllowIn,
+            StationSignalRole::Done,
+            StationSignalRole::Fault,
+        ];
+        for role in known {
+            assert!(SIGNAL_ROLES.contains(&role.as_str()));
+        }
+    }
+}
diff --git a/crates/app_operation_system/src/lib.rs b/crates/app_operation_system/src/lib.rs
index f54e2f1..f5d717a 100644
--- a/crates/app_operation_system/src/lib.rs
+++ b/crates/app_operation_system/src/lib.rs
@@ -2,7 +2,9 @@ pub mod app;
 pub mod control;
 pub mod event;
 pub mod handler;
+pub mod model;
 pub mod router;
+pub mod service;
 
 pub use app::{run, test_state, AppState};
 pub use router::build_router;
diff --git a/crates/app_operation_system/src/model.rs b/crates/app_operation_system/src/model.rs
new file mode 100644
index 0000000..21b715d
--- /dev/null
+++ b/crates/app_operation_system/src/model.rs
@@ -0,0 +1,292 @@
+use chrono::{DateTime, Utc};
+use plc_platform_core::util::datetime::utc_to_local_str;
+use serde::{Deserialize, Serialize};
+use sqlx::FromRow;
+use uuid::Uuid;
+
+// Station (design doc §4.2.1)
+
+#[derive(Debug, Clone, Serialize, Deserialize, FromRow)]
+pub struct Station {
+    pub id: Uuid,
+    pub code: String,
+    pub name: String,
+    pub line_code: Option<String>,
+    pub segment_code: Option<String>,
+    pub station_type: String,
+    pub enabled: bool,
+    pub description: Option<String>,
+    #[serde(serialize_with = "utc_to_local_str")]
+    pub created_at: DateTime<Utc>,
+    #[serde(serialize_with = "utc_to_local_str")]
+    pub updated_at: DateTime<Utc>,
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum StationType {
+    Load,
+    DryIn,
+    DryStep,
+    DryOut,
+    FireIn,
+    FireStep,
+    FireOut,
+    Transfer,
+    Unload,
+    Return,
+}
+
+impl StationType {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            StationType::Load => "load",
+            StationType::DryIn => "dry_in",
+            StationType::DryStep => "dry_step",
+            StationType::DryOut => "dry_out",
+            StationType::FireIn => "fire_in",
+            StationType::FireStep => "fire_step",
+            StationType::FireOut => "fire_out",
+            StationType::Transfer => "transfer",
+            StationType::Unload => "unload",
+            StationType::Return => "return",
+        }
+    }
+}
+
+// StationSignal (design doc §4.2.2)
+
+#[derive(Debug, Clone, Serialize, Deserialize, FromRow)]
+pub struct StationSignal {
+    pub id: Uuid,
+    pub station_id: Uuid,
+    pub signal_role: String,
+    pub point_id: Option<Uuid>,
+    pub derived_from_role: Option<String>,
+    pub invert_value: bool,
+    #[serde(serialize_with = "utc_to_local_str")]
+    pub created_at: DateTime<Utc>,
+    #[serde(serialize_with = "utc_to_local_str")]
+    pub updated_at: DateTime<Utc>,
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum StationSignalRole {
+    Presence,
+    Vacancy,
+    Arrived,
+    AllowIn,
+    Done,
+    Fault,
+}
+
+impl StationSignalRole {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            StationSignalRole::Presence => "presence",
+            StationSignalRole::Vacancy => "vacancy",
+            StationSignalRole::Arrived => "arrived",
+            StationSignalRole::AllowIn => "allow_in",
+            StationSignalRole::Done => "done",
+            StationSignalRole::Fault => "fault",
+        }
+    }
+}
+
+// ProcessSegment (design doc §4.2.3)
+
+#[derive(Debug, Clone, Serialize, Deserialize, FromRow)]
+pub struct ProcessSegment {
+    pub id: Uuid,
+    pub code: String,
+    pub name: String,
+    pub segment_type: String,
+    pub line_code: Option<String>,
+    pub priority: i32,
+    pub enabled: bool,
+    pub mode: String,
+    pub require_manual_ack_after_fault: bool,
+    pub description: Option<String>,
+    #[serde(serialize_with = "utc_to_local_str")]
+    pub created_at: DateTime<Utc>,
+    #[serde(serialize_with = "utc_to_local_str")]
+    pub updated_at: DateTime<Utc>,
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum SegmentMode {
+    Auto,
+    RemoteManual,
+    LocalManual,
+    Disabled,
+}
+
+impl SegmentMode {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            SegmentMode::Auto => "auto",
+            SegmentMode::RemoteManual => "remote_manual",
+            SegmentMode::LocalManual => "local_manual",
+            SegmentMode::Disabled => "disabled",
+        }
+    }
+}
+
+// SegmentStep (design doc §4.2.4)
+
+#[derive(Debug, Clone, Serialize, Deserialize, FromRow)]
+pub struct SegmentStep {
+    pub id: Uuid,
+    pub segment_id: Uuid,
+    pub step_no: i32,
+    pub step_code: String,
+    pub action_kind: String,
+    pub target_equipment_id: Option<Uuid>,
+    pub target_station_id: Option<Uuid>,
+    pub confirm_signal_role: Option<String>,
+    pub confirm_point_id: Option<Uuid>,
+    pub expected_value: bool,
+    pub timeout_ms: i32,
+    pub command_role: Option<String>,
+    pub stop_command_role: Option<String>,
+    pub pulse_ms: Option<i32>,
+    pub hold_until_confirm: bool,
+    pub cancel_on_fault: bool,
+    pub next_step_no_on_success: Option<i32>,
+    pub next_step_no_on_failure: Option<i32>,
+    pub on_timeout: String,
+    pub description: Option<String>,
+    #[serde(serialize_with = "utc_to_local_str")]
+    pub created_at: DateTime<Utc>,
+    #[serde(serialize_with = "utc_to_local_str")]
+    pub updated_at: DateTime<Utc>,
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum ActionKind {
+    OpenDoor,
+    CloseDoor,
+    PushForward,
+    PushRetract,
+    PullRun,
+    PullRetract,
+    TransferMoveTo,
+    StepOnce,
+    RobotPermit,
+    RobotRelease,
+    WaitSignal,
+    PulseCmd,
+}
+
+impl ActionKind {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            ActionKind::OpenDoor => "open_door",
+            ActionKind::CloseDoor => "close_door",
+            ActionKind::PushForward => "push_forward",
+            ActionKind::PushRetract => "push_retract",
+            ActionKind::PullRun => "pull_run",
+            ActionKind::PullRetract => "pull_retract",
+            ActionKind::TransferMoveTo => "transfer_move_to",
+            ActionKind::StepOnce => "step_once",
+            ActionKind::RobotPermit => "robot_permit",
+            ActionKind::RobotRelease => "robot_release",
+            ActionKind::WaitSignal => "wait_signal",
+            ActionKind::PulseCmd => "pulse_cmd",
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum OnTimeout {
+    Fault,
+    Retry,
+    Block,
+}
+
+impl OnTimeout {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            OnTimeout::Fault => "fault",
+            OnTimeout::Retry => "retry",
+            OnTimeout::Block => "block",
+        }
+    }
+}
+
+// SegmentInterlock (design doc §4.2.5)
+
+#[derive(Debug, Clone, Serialize, Deserialize, FromRow)]
+pub struct SegmentInterlock {
+    pub id: Uuid,
+    pub segment_id: Uuid,
+    pub applies_to: String,
+    pub rule_kind: String,
+    pub point_id: Option<Uuid>,
+    pub station_id: Option<Uuid>,
+    pub equipment_id: Option<Uuid>,
+    pub expected_value: Option<bool>,
+    pub description: Option<String>,
+    #[serde(serialize_with = "utc_to_local_str")]
+    pub created_at: DateTime<Utc>,
+    #[serde(serialize_with = "utc_to_local_str")]
+    pub updated_at: DateTime<Utc>,
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum InterlockAppliesTo {
+    StartAllow,
+    StartDeny,
+    RunHalt,
+}
+
+impl InterlockAppliesTo {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            InterlockAppliesTo::StartAllow => "start_allow",
+            InterlockAppliesTo::StartDeny => "start_deny",
+            InterlockAppliesTo::RunHalt => "run_halt",
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum RuleKind {
+    PointEq,
+    StationVacant,
+    StationOccupied,
+    EquipmentOrigin,
+    EquipmentNoFault,
+    EquipmentRemote,
+    SafetyChainOk,
+}
+
+impl RuleKind {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            RuleKind::PointEq => "point_eq",
+            RuleKind::StationVacant => "station_vacant",
+            RuleKind::StationOccupied => "station_occupied",
+            RuleKind::EquipmentOrigin => "equipment_origin",
+            RuleKind::EquipmentNoFault => "equipment_no_fault",
+            RuleKind::EquipmentRemote => "equipment_remote",
+            RuleKind::SafetyChainOk => "safety_chain_ok",
+        }
+    }
+}
+
+// SegmentResource (design doc §4.2.7)
+
+#[derive(Debug, Clone, Serialize, Deserialize, FromRow)]
+pub struct SegmentResource {
+    pub segment_id: Uuid,
+    pub resource_key: String,
+    #[serde(serialize_with = "utc_to_local_str")]
+    pub created_at: DateTime<Utc>,
+}
diff --git a/crates/app_operation_system/src/router.rs b/crates/app_operation_system/src/router.rs
index 28ed1f9..28fd2d6 100644
--- a/crates/app_operation_system/src/router.rs
+++ b/crates/app_operation_system/src/router.rs
@@ -1,4 +1,8 @@
-use axum::{extract::State, routing::get, Router};
+use axum::{
+    extract::State,
+    routing::{get, post, put},
+    Router,
+};
 
 use crate::app::AppState;
 
@@ -6,7 +10,67 @@ pub fn build_router(state: AppState) -> Router {
     // Platform routes (source, point, equipment, tag, page, logs) from core.
     let platform = plc_platform_core::handler::platform_routes::<AppState>();
 
-    // Ops-specific routes.
+    // Ops configuration routes (design doc §9.1).
+    let config_routes = Router::new()
+        .route(
+            "/api/station",
+            get(crate::handler::station::list_stations)
+                .post(crate::handler::station::create_station),
+        )
+        .route(
+            "/api/station/{station_id}",
+            get(crate::handler::station::get_station)
+                .put(crate::handler::station::update_station)
+                .delete(crate::handler::station::delete_station),
+        )
+        .route(
+            "/api/station/{station_id}/signal",
+            post(crate::handler::station::upsert_station_signal),
+        )
+        .route(
+            "/api/station/{station_id}/signal/{role}",
+            axum::routing::delete(crate::handler::station::delete_station_signal),
+        )
+        .route(
+            "/api/segment",
+            get(crate::handler::segment::list_segments)
+                .post(crate::handler::segment::create_segment),
+        )
+        .route(
+            "/api/segment/{segment_id}",
+            get(crate::handler::segment::get_segment)
+                .put(crate::handler::segment::update_segment)
+                .delete(crate::handler::segment::delete_segment),
+        )
+        .route(
+            "/api/segment/{segment_id}/detail",
+            get(crate::handler::segment::get_segment_detail),
+        )
+        .route(
+            "/api/segment/{segment_id}/step",
+            get(crate::handler::segment::list_steps)
+                .post(crate::handler::segment::create_step),
+        )
+        .route(
+            "/api/segment/{segment_id}/step/{step_no}",
+            put(crate::handler::segment::update_step)
+                .delete(crate::handler::segment::delete_step),
+        )
+        .route(
+            "/api/segment/{segment_id}/interlock",
+            get(crate::handler::segment::list_interlocks)
+                .post(crate::handler::segment::create_interlock),
+        )
+        .route(
+            "/api/segment/{segment_id}/interlock/{interlock_id}",
+            axum::routing::delete(crate::handler::segment::delete_interlock),
+        )
+        .route(
+            "/api/segment/{segment_id}/resource",
+            get(crate::handler::segment::list_resources)
+                .put(crate::handler::segment::replace_resources),
+        );
+
     let ops_routes = Router::new()
         .route("/api/health", get(health_check))
         .route("/api/docs/api-md", get(crate::handler::doc::get_api_md))
@@ -17,6 +81,7 @@ pub fn build_router(state: AppState) -> Router {
 
     Router::new()
         .merge(platform)
+        .merge(config_routes)
         .merge(ops_routes)
         .nest(
             "/ui",
diff --git a/crates/app_operation_system/src/service.rs b/crates/app_operation_system/src/service.rs
new file mode 100644
index 0000000..c53bf6a
--- /dev/null
+++ b/crates/app_operation_system/src/service.rs
@@ -0,0 +1,2 @@
+pub mod segment;
+pub mod station;
diff --git a/crates/app_operation_system/src/service/segment.rs b/crates/app_operation_system/src/service/segment.rs
new file mode 100644
index 0000000..b83d605
--- /dev/null
+++ b/crates/app_operation_system/src/service/segment.rs
@@ -0,0 +1,443 @@
+use sqlx::PgPool;
+use uuid::Uuid;
+
+use crate::model::{ProcessSegment, SegmentInterlock, SegmentResource, SegmentStep};
+
+// process_segment
+
+pub async fn list_segments(
+    pool: &PgPool,
+    line_code: Option<&str>,
+) -> Result<Vec<ProcessSegment>, sqlx::Error> {
+    match line_code {
+        Some(line) => sqlx::query_as::<_, ProcessSegment>(
+            r#"SELECT * FROM process_segment WHERE line_code = $1 ORDER BY priority DESC, code"#,
+        )
+        .bind(line)
+        .fetch_all(pool)
+        .await,
+        None => sqlx::query_as::<_, ProcessSegment>(
+            r#"SELECT * FROM process_segment ORDER BY priority DESC, code"#,
+        )
+        .fetch_all(pool)
+        .await,
+    }
+}
+
+pub async fn get_segment_by_id(
+    pool: &PgPool,
+    segment_id: Uuid,
+) -> Result<Option<ProcessSegment>, sqlx::Error> {
+    sqlx::query_as::<_, ProcessSegment>(r#"SELECT * FROM process_segment WHERE id = $1"#)
+        .bind(segment_id)
+        .fetch_optional(pool)
+        .await
+}
+
+pub async fn get_segment_by_code(
+    pool: &PgPool,
+    code: &str,
+) -> Result<Option<ProcessSegment>, sqlx::Error> {
+    sqlx::query_as::<_, ProcessSegment>(r#"SELECT * FROM process_segment WHERE code = $1"#)
+        .bind(code)
+        .fetch_optional(pool)
+        .await
+}
+
+pub struct CreateSegmentParams<'a> {
+    pub code: &'a str,
+    pub name: &'a str,
+    pub segment_type: &'a str,
+    pub line_code: Option<&'a str>,
+    pub priority: i32,
+    pub enabled: bool,
+    pub mode: &'a str,
+    pub require_manual_ack_after_fault: bool,
+    pub description: Option<&'a str>,
+}
+
+pub async fn create_segment(
+    pool: &PgPool,
+    params: CreateSegmentParams<'_>,
+) -> Result<Uuid, sqlx::Error> {
+    let segment_id = Uuid::new_v4();
+    sqlx::query(
+        r#"
+        INSERT INTO process_segment (
+            id, code, name, segment_type, line_code, priority,
+            enabled, mode, require_manual_ack_after_fault, description
+        )
+        VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)
+        "#,
+    )
+    .bind(segment_id)
+    .bind(params.code)
+    .bind(params.name)
+    .bind(params.segment_type)
+    .bind(params.line_code)
+    .bind(params.priority)
+    .bind(params.enabled)
+    .bind(params.mode)
+    .bind(params.require_manual_ack_after_fault)
+    .bind(params.description)
+    .execute(pool)
+    .await?;
+    Ok(segment_id)
+}
+
+pub struct UpdateSegmentParams<'a> {
+    pub code: Option<&'a str>,
+    pub name: Option<&'a str>,
+    pub segment_type: Option<&'a str>,
+    pub line_code: Option<&'a str>,
+    pub priority: Option<i32>,
+    pub enabled: Option<bool>,
+    pub mode: Option<&'a str>,
+    pub require_manual_ack_after_fault: Option<bool>,
+    pub description: Option<&'a str>,
+}
+
+pub async fn update_segment(
+    pool: &PgPool,
+    segment_id: Uuid,
+    params: UpdateSegmentParams<'_>,
+) -> Result<bool, sqlx::Error> {
+    let result = sqlx::query(
+        r#"
+        UPDATE process_segment SET
+            code = COALESCE($2, code),
+            name = COALESCE($3, name),
+            segment_type = COALESCE($4, segment_type),
+            line_code = COALESCE($5, line_code),
+            priority = COALESCE($6, priority),
+            enabled = COALESCE($7, enabled),
+            mode = COALESCE($8, mode),
+            require_manual_ack_after_fault = COALESCE($9, require_manual_ack_after_fault),
+            description = COALESCE($10, description),
+            updated_at = NOW()
+        WHERE id = $1
+        "#,
+    )
+    .bind(segment_id)
+    .bind(params.code)
+    .bind(params.name)
+    .bind(params.segment_type)
+    .bind(params.line_code)
+    .bind(params.priority)
+    .bind(params.enabled)
+    .bind(params.mode)
+    .bind(params.require_manual_ack_after_fault)
+    .bind(params.description)
+    .execute(pool)
+    .await?;
+    Ok(result.rows_affected() > 0)
+}
+
+pub async fn delete_segment(pool: &PgPool, segment_id: Uuid) -> Result<bool, sqlx::Error> {
+    let result = sqlx::query(r#"DELETE FROM process_segment WHERE id = $1"#)
+        .bind(segment_id)
+        .execute(pool)
+        .await?;
+    Ok(result.rows_affected() > 0)
+}
+
+// segment_step
+
+pub async fn list_steps(
+    pool: &PgPool,
+    segment_id: Uuid,
+) -> Result<Vec<SegmentStep>, sqlx::Error> {
+    sqlx::query_as::<_, SegmentStep>(
+        r#"SELECT * FROM segment_step WHERE segment_id = $1 ORDER BY step_no"#,
+    )
+    .bind(segment_id)
+    .fetch_all(pool)
+    .await
+}
+
+pub async fn get_step(
+    pool: &PgPool,
+    segment_id: Uuid,
+    step_no: i32,
+) -> Result<Option<SegmentStep>, sqlx::Error> {
+    sqlx::query_as::<_, SegmentStep>(
+        r#"SELECT * FROM segment_step WHERE segment_id = $1 AND step_no = $2"#,
+    )
+    .bind(segment_id)
+    .bind(step_no)
+    .fetch_optional(pool)
+    .await
+}
+
+pub struct CreateStepParams<'a> {
+    pub segment_id: Uuid,
+    pub step_no: i32,
+    pub step_code: &'a str,
+    pub action_kind: &'a str,
+    pub target_equipment_id: Option<Uuid>,
+    pub target_station_id: Option<Uuid>,
+    pub confirm_signal_role: Option<&'a str>,
+    pub confirm_point_id: Option<Uuid>,
+    pub expected_value: bool,
+    pub timeout_ms: i32,
+    pub command_role: Option<&'a str>,
+    pub stop_command_role: Option<&'a str>,
+    pub pulse_ms: Option<i32>,
+    pub hold_until_confirm: bool,
+    pub cancel_on_fault: bool,
+    pub next_step_no_on_success: Option<i32>,
+    pub next_step_no_on_failure: Option<i32>,
+    pub on_timeout: &'a str,
+    pub description: Option<&'a str>,
+}
+
+pub async fn create_step(pool: &PgPool, params: CreateStepParams<'_>) -> Result<Uuid, sqlx::Error> {
+    let step_id = Uuid::new_v4();
+    sqlx::query(
+        r#"
+        INSERT INTO segment_step (
+            id, segment_id, step_no, step_code, action_kind,
+            target_equipment_id, target_station_id,
+            confirm_signal_role, confirm_point_id, expected_value,
+            timeout_ms, command_role, stop_command_role, pulse_ms,
+            hold_until_confirm, cancel_on_fault,
+            next_step_no_on_success, next_step_no_on_failure,
+            on_timeout, description
+        )
+        VALUES (
+            $1, $2, $3, $4, $5,
+            $6, $7,
+            $8, $9, $10,
+            $11, $12, $13, $14,
+            $15, $16,
+            $17, $18,
+            $19, $20
+        )
+        "#,
+    )
+    .bind(step_id)
+    .bind(params.segment_id)
+    .bind(params.step_no)
+    .bind(params.step_code)
+    .bind(params.action_kind)
+    .bind(params.target_equipment_id)
+    .bind(params.target_station_id)
+    .bind(params.confirm_signal_role)
+    .bind(params.confirm_point_id)
+    .bind(params.expected_value)
+    .bind(params.timeout_ms)
+    .bind(params.command_role)
+    .bind(params.stop_command_role)
+    .bind(params.pulse_ms)
+    .bind(params.hold_until_confirm)
+    .bind(params.cancel_on_fault)
+    .bind(params.next_step_no_on_success)
+    .bind(params.next_step_no_on_failure)
+    .bind(params.on_timeout)
+    .bind(params.description)
+    .execute(pool)
+    .await?;
+    Ok(step_id)
+}
+
+pub struct UpdateStepParams<'a> {
+    pub step_code: Option<&'a str>,
+    pub action_kind: Option<&'a str>,
+    pub target_equipment_id: Option<Uuid>,
+    pub target_station_id: Option<Uuid>,
+    pub confirm_signal_role: Option<&'a str>,
+    pub confirm_point_id: Option<Uuid>,
+    pub expected_value: Option<bool>,
+    pub timeout_ms: Option<i32>,
+    pub command_role: Option<&'a str>,
+    pub stop_command_role: Option<&'a str>,
+    pub pulse_ms: Option<i32>,
+    pub hold_until_confirm: Option<bool>,
+    pub cancel_on_fault: Option<bool>,
+    pub next_step_no_on_success: Option<i32>,
+    pub next_step_no_on_failure: Option<i32>,
+    pub on_timeout: Option<&'a str>,
+    pub description: Option<&'a str>,
+}
+
+pub async fn update_step(
+    pool: &PgPool,
+    segment_id: Uuid,
+    step_no: i32,
+    params: UpdateStepParams<'_>,
+) -> Result<bool, sqlx::Error> {
+    let result = sqlx::query(
+        r#"
+        UPDATE segment_step SET
+            step_code = COALESCE($3, step_code),
+            action_kind = COALESCE($4, action_kind),
+            target_equipment_id = COALESCE($5, target_equipment_id),
+            target_station_id = COALESCE($6, target_station_id),
+            confirm_signal_role = COALESCE($7, confirm_signal_role),
+            confirm_point_id = COALESCE($8, confirm_point_id),
+            expected_value = COALESCE($9, expected_value),
+            timeout_ms = COALESCE($10, timeout_ms),
+            command_role = COALESCE($11, command_role),
+            stop_command_role = COALESCE($12, stop_command_role),
+            pulse_ms = COALESCE($13, pulse_ms),
+            hold_until_confirm = COALESCE($14, hold_until_confirm),
+            cancel_on_fault = COALESCE($15, cancel_on_fault),
+            next_step_no_on_success = COALESCE($16, next_step_no_on_success),
+            next_step_no_on_failure = COALESCE($17, next_step_no_on_failure),
+            on_timeout = COALESCE($18, on_timeout),
+            description = COALESCE($19, description),
+            updated_at = NOW()
+        WHERE segment_id = $1 AND step_no = $2
+        "#,
+    )
+    .bind(segment_id)
+    .bind(step_no)
+    .bind(params.step_code)
+    .bind(params.action_kind)
+    .bind(params.target_equipment_id)
+    .bind(params.target_station_id)
+    .bind(params.confirm_signal_role)
+    .bind(params.confirm_point_id)
+    .bind(params.expected_value)
+    .bind(params.timeout_ms)
+    .bind(params.command_role)
+    .bind(params.stop_command_role)
+    .bind(params.pulse_ms)
+    .bind(params.hold_until_confirm)
+    .bind(params.cancel_on_fault)
+    .bind(params.next_step_no_on_success)
+    .bind(params.next_step_no_on_failure)
+    .bind(params.on_timeout)
+    .bind(params.description)
+    .execute(pool)
+    .await?;
+    Ok(result.rows_affected() > 0)
+}
+
+pub async fn delete_step(
+    pool: &PgPool,
+    segment_id: Uuid,
+    step_no: i32,
+) -> Result<bool, sqlx::Error> {
+    let result =
+        sqlx::query(r#"DELETE FROM segment_step WHERE segment_id = $1 AND step_no = $2"#)
+            .bind(segment_id)
+            .bind(step_no)
+            .execute(pool)
+            .await?;
+    Ok(result.rows_affected() > 0)
+}
+
+// segment_interlock
+
+pub async fn list_interlocks(
+    pool: &PgPool,
+    segment_id: Uuid,
+) -> Result<Vec<SegmentInterlock>, sqlx::Error> {
+    sqlx::query_as::<_, SegmentInterlock>(
+        r#"SELECT * FROM segment_interlock WHERE segment_id = $1 ORDER BY applies_to, id"#,
+    )
+    .bind(segment_id)
+    .fetch_all(pool)
+    .await
+}
+
+pub struct CreateInterlockParams<'a> {
+    pub segment_id: Uuid,
+    pub applies_to: &'a str,
+    pub rule_kind: &'a str,
+    pub point_id: Option<Uuid>,
+    pub station_id: Option<Uuid>,
+    pub equipment_id: Option<Uuid>,
+    pub expected_value: Option<bool>,
+    pub description: Option<&'a str>,
+}
+
+pub async fn create_interlock(
+    pool: &PgPool,
+    params: CreateInterlockParams<'_>,
+) -> Result<Uuid, sqlx::Error> {
+    let interlock_id = Uuid::new_v4();
+    sqlx::query(
+        r#"
+        INSERT INTO segment_interlock (
+            id, segment_id, applies_to, rule_kind,
+            point_id, station_id, equipment_id,
+            expected_value, description
+        )
+        VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
+        "#,
+    )
+    .bind(interlock_id)
+    .bind(params.segment_id)
+    .bind(params.applies_to)
+    .bind(params.rule_kind)
+    .bind(params.point_id)
+    .bind(params.station_id)
+    .bind(params.equipment_id)
+    .bind(params.expected_value)
+    .bind(params.description)
+    .execute(pool)
+    .await?;
+    Ok(interlock_id)
+}
+
+pub async fn delete_interlock(
+    pool: &PgPool,
+    segment_id: Uuid,
+    interlock_id: Uuid,
+) -> Result<bool, sqlx::Error> {
+    let result = sqlx::query(
+        r#"DELETE FROM segment_interlock WHERE segment_id = $1 AND id = $2"#,
+    )
+    .bind(segment_id)
+    .bind(interlock_id)
+    .execute(pool)
+    .await?;
+    Ok(result.rows_affected() > 0)
+}
+
+// segment_resource
+
+pub async fn list_resources(
+    pool: &PgPool,
+    segment_id: Uuid,
+) -> Result<Vec<SegmentResource>, sqlx::Error> {
+    sqlx::query_as::<_, SegmentResource>(
+        r#"SELECT * FROM segment_resource WHERE segment_id = $1 ORDER BY resource_key"#,
+    )
+    .bind(segment_id)
+    .fetch_all(pool)
+    .await
+}
+
+/// Replace the entire resource set for a segment.
+/// Empty `keys` clears all resources for the segment.
+pub async fn replace_resources(
+    pool: &PgPool,
+    segment_id: Uuid,
+    keys: &[String],
+) -> Result<(), sqlx::Error> {
+    let mut tx = pool.begin().await?;
+
+    sqlx::query(r#"DELETE FROM segment_resource WHERE segment_id = $1"#)
+        .bind(segment_id)
+        .execute(&mut *tx)
+        .await?;
+
+    for key in keys {
+        sqlx::query(
+            r#"
+            INSERT INTO segment_resource (segment_id, resource_key)
+            VALUES ($1, $2)
+            ON CONFLICT DO NOTHING
+            "#,
+        )
+        .bind(segment_id)
+        .bind(key)
+        .execute(&mut *tx)
+        .await?;
+    }
+
+    tx.commit().await
+}
diff --git a/crates/app_operation_system/src/service/station.rs b/crates/app_operation_system/src/service/station.rs
new file mode 100644
index 0000000..5a37ead
--- /dev/null
+++ b/crates/app_operation_system/src/service/station.rs
@@ -0,0 +1,191 @@
+use sqlx::PgPool;
+use uuid::Uuid;
+
+use crate::model::{Station, StationSignal};
+
+pub async fn list_stations(
+    pool: &PgPool,
+    line_code: Option<&str>,
+) -> Result<Vec<Station>, sqlx::Error> {
+    match line_code {
+        Some(line) => sqlx::query_as::<_, Station>(
+            r#"SELECT * FROM station WHERE line_code = $1 ORDER BY code"#,
+        )
+        .bind(line)
+        .fetch_all(pool)
+        .await,
+        None => sqlx::query_as::<_, Station>(r#"SELECT * FROM station ORDER BY code"#)
+            .fetch_all(pool)
+            .await,
+    }
+}
+
+pub async fn get_station_by_id(
+    pool: &PgPool,
+    station_id: Uuid,
+) -> Result<Option<Station>, sqlx::Error> {
+    sqlx::query_as::<_, Station>(r#"SELECT * FROM station WHERE id = $1"#)
+        .bind(station_id)
+        .fetch_optional(pool)
+        .await
+}
+
+pub async fn get_station_by_code(
+    pool: &PgPool,
+    code: &str,
+) -> Result<Option<Station>, sqlx::Error> {
+    sqlx::query_as::<_, Station>(r#"SELECT * FROM station WHERE code = $1"#)
+        .bind(code)
+        .fetch_optional(pool)
+        .await
+}
+
+pub struct CreateStationParams<'a> {
+    pub code: &'a str,
+    pub name: &'a str,
+    pub line_code: Option<&'a str>,
+    pub segment_code: Option<&'a str>,
+    pub station_type: &'a str,
+    pub enabled: bool,
+    pub description: Option<&'a str>,
+}
+
+pub async fn create_station(
+    pool: &PgPool,
+    params: CreateStationParams<'_>,
+) -> Result<Uuid, sqlx::Error> {
+    let station_id = Uuid::new_v4();
+    sqlx::query(
+        r#"
+        INSERT INTO station (
+            id, code, name, line_code, segment_code, station_type, enabled, description
+        )
+        VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
+        "#,
+    )
+    .bind(station_id)
+    .bind(params.code)
+    .bind(params.name)
+    .bind(params.line_code)
+    .bind(params.segment_code)
+    .bind(params.station_type)
+    .bind(params.enabled)
+    .bind(params.description)
+    .execute(pool)
+    .await?;
+
+    Ok(station_id)
+}
+
+pub struct UpdateStationParams<'a> {
+    pub code: Option<&'a str>,
+    pub name: Option<&'a str>,
+    pub line_code: Option<&'a str>,
+    pub segment_code: Option<&'a str>,
+    pub station_type: Option<&'a str>,
+    pub enabled: Option<bool>,
+    pub description: Option<&'a str>,
+}
+
+pub async fn update_station(
+    pool: &PgPool,
+    station_id: Uuid,
+    params: UpdateStationParams<'_>,
+) -> Result<bool, sqlx::Error> {
+    let result = sqlx::query(
+        r#"
+        UPDATE station SET
+            code = COALESCE($2, code),
+            name = COALESCE($3, name),
+            line_code = COALESCE($4, line_code),
+            segment_code = COALESCE($5, segment_code),
+            station_type = COALESCE($6, station_type),
+            enabled = COALESCE($7, enabled),
+            description = COALESCE($8, description),
+            updated_at = NOW()
+        WHERE id = $1
+        "#,
+    )
+    .bind(station_id)
+    .bind(params.code)
+    .bind(params.name)
+    .bind(params.line_code)
+    .bind(params.segment_code)
+    .bind(params.station_type)
+    .bind(params.enabled)
+    .bind(params.description)
+    .execute(pool)
+    .await?;
+
+    Ok(result.rows_affected() > 0)
+}
+
+pub async fn delete_station(pool: &PgPool, station_id: Uuid) -> Result<bool, sqlx::Error> {
+    let result = sqlx::query(r#"DELETE FROM station WHERE id = $1"#)
+        .bind(station_id)
+        .execute(pool)
+        .await?;
+    Ok(result.rows_affected() > 0)
+}
+
+pub async fn list_station_signals(
+    pool: &PgPool,
+    station_id: Uuid,
+) -> Result<Vec<StationSignal>, sqlx::Error> {
+    sqlx::query_as::<_, StationSignal>(
+        r#"SELECT * FROM station_signal WHERE station_id = $1 ORDER BY signal_role"#,
+    )
+    .bind(station_id)
+    .fetch_all(pool)
+    .await
+}
+
+pub struct UpsertStationSignalParams {
+    pub signal_role: String,
+    pub point_id: Option<Uuid>,
+    pub derived_from_role: Option<String>,
+    pub invert_value: bool,
+}
+
+pub async fn upsert_station_signal(
+    pool: &PgPool,
+    station_id: Uuid,
+    params: UpsertStationSignalParams,
+) -> Result<StationSignal, sqlx::Error> {
+    sqlx::query_as::<_, StationSignal>(
+        r#"
+        INSERT INTO station_signal (
+            station_id, signal_role, point_id, derived_from_role, invert_value
+        )
+        VALUES ($1, $2, $3, $4, $5)
+        ON CONFLICT (station_id, signal_role) DO UPDATE SET
+            point_id = EXCLUDED.point_id,
+            derived_from_role = EXCLUDED.derived_from_role,
+            invert_value = EXCLUDED.invert_value,
+            updated_at = NOW()
+        RETURNING *
+        "#,
+    )
+    .bind(station_id)
+    .bind(&params.signal_role)
+    .bind(params.point_id)
+    .bind(&params.derived_from_role)
+    .bind(params.invert_value)
+    .fetch_one(pool)
+    .await
+}
+
+pub async fn delete_station_signal(
+    pool: &PgPool,
+    station_id: Uuid,
+    signal_role: &str,
+) -> Result<bool, sqlx::Error> {
+    let result = sqlx::query(
+        r#"DELETE FROM station_signal WHERE station_id = $1 AND signal_role = $2"#,
+    )
+    .bind(station_id)
+    .bind(signal_role)
+    .execute(pool)
+    .await?;
+    Ok(result.rows_affected() > 0)
+}
diff --git a/crates/app_operation_system/tests/router_smoke.rs b/crates/app_operation_system/tests/router_smoke.rs
index d621193..fee76d3 100644
--- a/crates/app_operation_system/tests/router_smoke.rs
+++ b/crates/app_operation_system/tests/router_smoke.rs
@@ -4,11 +4,13 @@ use axum::{
 };
 use tower::ServiceExt;
 
+fn build_app() -> axum::Router {
+    app_operation_system::build_router(app_operation_system::app::test_state())
+}
+
 #[tokio::test]
 async fn operation_system_router_exposes_health_endpoint() {
-    let app = app_operation_system::build_router(app_operation_system::app::test_state());
-
-    let response = app
+    let response = build_app()
         .oneshot(
             Request::builder()
                 .method(Method::GET)
@@ -21,3 +23,37 @@ async fn operation_system_router_exposes_health_endpoint() {
 
     assert_eq!(response.status(), StatusCode::OK);
 }
+
+/// Verify the station collection route is registered (DELETE on the collection
+/// isn't a real method, so axum should answer METHOD_NOT_ALLOWED, not 404).
+#[tokio::test]
+async fn operation_system_router_exposes_station_collection() {
+    let response = build_app()
+        .oneshot(
+            Request::builder()
+                .method(Method::DELETE)
+                .uri("/api/station")
+                .body(Body::empty())
+                .expect("request should build"),
+        )
+        .await
+        .expect("router should answer request");
+
+    assert_eq!(response.status(), StatusCode::METHOD_NOT_ALLOWED);
+}
+
+#[tokio::test]
+async fn operation_system_router_exposes_segment_collection() {
+    let response = build_app()
+        .oneshot(
+            Request::builder()
+                .method(Method::DELETE)
+                .uri("/api/segment")
+                .body(Body::empty())
+                .expect("request should build"),
+        )
+        .await
+        .expect("router should answer request");
+
+    assert_eq!(response.status(), StatusCode::METHOD_NOT_ALLOWED);
+}
diff --git a/migrations/20260518090000_create_operation_system.sql b/migrations/20260518090000_create_operation_system.sql
new file mode 100644
index 0000000..8b6248d
--- /dev/null
+++ b/migrations/20260518090000_create_operation_system.sql
@@ -0,0 +1,116 @@
+-- Operation-system business tables (design doc §4 / §12 P1).
+-- Six ops configuration tables + event attribution columns.
+
+-- 1. station: 工位
+CREATE TABLE station (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    code TEXT NOT NULL,
+    name TEXT NOT NULL,
+    line_code TEXT,
+    segment_code TEXT,
+    station_type TEXT NOT NULL,
+    enabled BOOLEAN NOT NULL DEFAULT TRUE,
+    description TEXT,
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    updated_at TIMESTAMPTZ DEFAULT NOW(),
+    UNIQUE (code)
+);
+
+CREATE INDEX idx_station_line_code ON station(line_code);
+CREATE INDEX idx_station_segment_code ON station(segment_code);
+
+-- 2. station_signal: 工位 ↔ 信号绑定
+CREATE TABLE station_signal (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    station_id UUID NOT NULL REFERENCES station(id) ON DELETE CASCADE,
+    signal_role TEXT NOT NULL,
+    point_id UUID REFERENCES point(id) ON DELETE SET NULL,
+    derived_from_role TEXT,
+    invert_value BOOLEAN NOT NULL DEFAULT FALSE,
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    updated_at TIMESTAMPTZ DEFAULT NOW(),
+    UNIQUE (station_id, signal_role)
+);
+
+CREATE INDEX idx_station_signal_point_id ON station_signal(point_id);
+
+-- 3. process_segment: 流程段
+CREATE TABLE process_segment (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    code TEXT NOT NULL,
+    name TEXT NOT NULL,
+    segment_type TEXT NOT NULL,
+    line_code TEXT,
+    priority INTEGER NOT NULL DEFAULT 0,
+    enabled BOOLEAN NOT NULL DEFAULT TRUE,
+    mode TEXT NOT NULL DEFAULT 'disabled',
+    require_manual_ack_after_fault BOOLEAN NOT NULL DEFAULT TRUE,
+    description TEXT,
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    updated_at TIMESTAMPTZ DEFAULT NOW(),
+    UNIQUE (code)
+);
+
+CREATE INDEX idx_process_segment_line_code ON process_segment(line_code);
+CREATE INDEX idx_process_segment_enabled ON process_segment(enabled);
+
+-- 4. segment_step: 段步骤
+CREATE TABLE segment_step (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    segment_id UUID NOT NULL REFERENCES process_segment(id) ON DELETE CASCADE,
+    step_no INTEGER NOT NULL,
+    step_code TEXT NOT NULL,
+    action_kind TEXT NOT NULL,
+    target_equipment_id UUID REFERENCES equipment(id) ON DELETE SET NULL,
+    target_station_id UUID REFERENCES station(id) ON DELETE SET NULL,
+    confirm_signal_role TEXT,
+    confirm_point_id UUID REFERENCES point(id) ON DELETE SET NULL,
+    expected_value BOOLEAN NOT NULL DEFAULT TRUE,
+    timeout_ms INTEGER NOT NULL DEFAULT 30000 CHECK (timeout_ms > 0),
+    command_role TEXT,
+    stop_command_role TEXT,
+    pulse_ms INTEGER CHECK (pulse_ms IS NULL OR pulse_ms > 0),
+    hold_until_confirm BOOLEAN NOT NULL DEFAULT FALSE,
+    cancel_on_fault BOOLEAN NOT NULL DEFAULT TRUE,
+    next_step_no_on_success INTEGER,
+    next_step_no_on_failure INTEGER,
+    on_timeout TEXT NOT NULL DEFAULT 'fault',
+    description TEXT,
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    updated_at TIMESTAMPTZ DEFAULT NOW(),
+    UNIQUE (segment_id, step_no)
+);
+
+CREATE INDEX idx_segment_step_segment_id ON segment_step(segment_id);
+
+-- 5. segment_interlock: 段联锁
+CREATE TABLE segment_interlock (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    segment_id UUID NOT NULL REFERENCES process_segment(id) ON DELETE CASCADE,
+    applies_to TEXT NOT NULL,
+    rule_kind TEXT NOT NULL,
+    point_id UUID REFERENCES point(id) ON DELETE SET NULL,
+    station_id UUID REFERENCES station(id) ON DELETE SET NULL,
+    equipment_id UUID REFERENCES equipment(id) ON DELETE SET NULL,
+    expected_value BOOLEAN,
+    description TEXT,
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    updated_at TIMESTAMPTZ DEFAULT NOW()
+);
+
+CREATE INDEX idx_segment_interlock_segment_id ON segment_interlock(segment_id);
+
+-- 6. segment_resource: 段资源声明
+CREATE TABLE segment_resource (
+    segment_id UUID NOT NULL REFERENCES process_segment(id) ON DELETE CASCADE,
+    resource_key TEXT NOT NULL,
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    PRIMARY KEY (segment_id, resource_key)
+);
+
+-- 7. event attribution: subject_type / subject_id (design doc §4.2.8)
+ALTER TABLE event
+    ADD COLUMN subject_type TEXT,
+    ADD COLUMN subject_id UUID;
+
+CREATE INDEX idx_event_subject ON event(subject_type, subject_id);