diff --git a/include/bitcoin/node/chase.hpp b/include/bitcoin/node/chase.hpp
index 557e3143..891be398 100644
--- a/include/bitcoin/node/chase.hpp
+++ b/include/bitcoin/node/chase.hpp
@@ -134,15 +134,15 @@ enum class chase
     /// -----------------------------------------------------------------------
 
     /// A current block has been organized (header_t).
-    /// Issued by 'transaction' and handled by 'protocol_header/block_out'.
+    /// Issued by 'confirm' and handled by 'protocol_header/block_out/estimator'.
     block,
 
     /// A confirmable block has been confirmed (header_t).
-    /// Issued by 'confirm' [and handled by 'transaction'].
+    /// Issued by 'confirm' and handled by 'transaction'.
     organized,
 
     /// A previously confirmed block has been unconfirmed (header_t).
-    /// Issued by 'confirm' [and handled by 'transaction'].
+    /// Issued by 'confirm' and handled by 'transaction'.
     reorganized,
 
     /// Mining.
diff --git a/include/bitcoin/node/chasers/chaser.hpp b/include/bitcoin/node/chasers/chaser.hpp
index 6d9cab57..bea55dc7 100644
--- a/include/bitcoin/node/chasers/chaser.hpp
+++ b/include/bitcoin/node/chasers/chaser.hpp
@@ -39,7 +39,7 @@ class BCN_API chaser
 public:
     DELETE_COPY_MOVE_DESTRUCT(chaser);
 
-    /// Must be called from node strand.
+    /// Should be called from node strand.
     virtual code start() NOEXCEPT = 0;
 
     /// Override to capture non-blocking stopping.
diff --git a/include/bitcoin/node/error.hpp b/include/bitcoin/node/error.hpp
index b9db21af..a4562997 100644
--- a/include/bitcoin/node/error.hpp
+++ b/include/bitcoin/node/error.hpp
@@ -98,6 +98,7 @@ enum error_t : uint8_t
     confirm10,
     confirm11,
     confirm12,
+    estimate_failed,
     estimates_failed,
     estimates_disabled,
     estimates_premature
diff --git a/src/chasers/chaser_check.cpp b/src/chasers/chaser_check.cpp
index 768ce4af..68e72f98 100644
--- a/src/chasers/chaser_check.cpp
+++ b/src/chasers/chaser_check.cpp
@@ -90,7 +90,6 @@ map_ptr chaser_check::split(const map_ptr& map) NOEXCEPT
 
 code chaser_check::start() NOEXCEPT
 {
-    BC_ASSERT(stranded());
     start_tracking();
     set_position(archive().get_fork());
     requested_ = advanced_ = position();
diff --git a/src/chasers/chaser_confirm.cpp b/src/chasers/chaser_confirm.cpp
index 56ee6a9e..d1fb50b7 100644
--- a/src/chasers/chaser_confirm.cpp
+++ b/src/chasers/chaser_confirm.cpp
@@ -42,7 +42,6 @@ chaser_confirm::chaser_confirm(full_node& node) NOEXCEPT
 
 code chaser_confirm::start() NOEXCEPT
 {
-    BC_ASSERT(stranded());
     const auto& query = archive();
     set_position(query.get_fork());
 
diff --git a/src/chasers/chaser_estimate.cpp b/src/chasers/chaser_estimate.cpp
index cbb9b0b5..5573985d 100644
--- a/src/chasers/chaser_estimate.cpp
+++ b/src/chasers/chaser_estimate.cpp
@@ -44,9 +44,7 @@ chaser_estimate::chaser_estimate(full_node& node) NOEXCEPT
 
 code chaser_estimate::start() NOEXCEPT
 {
-    BC_ASSERT(stranded());
-
-    if (is_zero(node_settings().fee_estimate_enabled()))
+    if (node_settings().fee_estimate_enabled())
     {
         SUBSCRIBE_CHASE(handle_chase, _1, _2, _3);
     }
@@ -72,12 +70,6 @@ void chaser_estimate::estimate(size_t target, estimator::mode mode,
         return;
     }
 
-    if (!initialized())
-    {
-        handler(error::estimates_premature, {});
-        return;
-    }
-
     POST(do_estimate, target, mode, std::move(handler));
 }
 
@@ -86,7 +78,20 @@ void chaser_estimate::do_estimate(size_t target, estimator::mode mode,
     const estimate_handler& handler) NOEXCEPT
 {
     BC_ASSERT(stranded());
-    handler(error::success, estimator_->estimate(target, mode));
+
+    // Check this under strand so that chase can initialize first.
+    if (!initialized())
+    {
+        handler(error::estimates_premature, {});
+        return;
+    }
+
+    const auto value = estimator_->estimate(target, mode);
+    const auto ec = (value < to_unsigned(max_int64) ? error::success :
+        error::estimate_failed);
+
+    // Successful value is always castable to int64_t.
+    handler(ec, value);
 }
 
 size_t chaser_estimate::top_height() const NOEXCEPT
@@ -113,12 +118,10 @@ bool chaser_estimate::handle_chase(const code&, chase event_,
     ////if (suspended())
     ////    return true;
 
-    if (!is_current(true))
-        return true;
-
     switch (event_)
     {
-        case chase::organized:
+        // chase::block is only sent when current (may need to file gaps).
+        case chase::block:
         {
             BC_ASSERT(std::holds_alternative<header_t>(value));
             POST(do_organized, std::get<header_t>(value));
@@ -147,7 +150,8 @@ void chaser_estimate::do_organized(header_t) NOEXCEPT
 {
     BC_ASSERT(stranded());
 
-    if (initialize())
+    // TODO: make gap safe (get estimator top and adjust).
+    if (initialized() || initialize())
         estimator_->push(archive());
 }
 
@@ -155,7 +159,8 @@ void chaser_estimate::do_reorganized(header_t) NOEXCEPT
 {
     BC_ASSERT(stranded());
 
-    if (initialize())
+    // TODO: make gap safe (get estimator top and adjust).
+    if (initialized())
         estimator_->pop(archive());
 }
 
@@ -167,9 +172,6 @@ bool chaser_estimate::initialize() NOEXCEPT
 {
     BC_ASSERT(stranded());
 
-    if (initialized())
-        return true;
-
     // Preempt initialize fault when horizon exceeds chain length.
     const auto horizon = node_settings().fee_estimate_horizon_();
     if (horizon > add1(archive().get_top_confirmed()))
diff --git a/src/chasers/chaser_header.cpp b/src/chasers/chaser_header.cpp
index 97a78388..0b0da56c 100644
--- a/src/chasers/chaser_header.cpp
+++ b/src/chasers/chaser_header.cpp
@@ -35,7 +35,6 @@ chaser_header::chaser_header(full_node& node) NOEXCEPT
 
 code chaser_header::start() NOEXCEPT
 {
-    BC_ASSERT(stranded());
     if (!initialize_milestone())
         return fault(error::header1);
 
diff --git a/src/chasers/chaser_snapshot.cpp b/src/chasers/chaser_snapshot.cpp
index 01a487d4..9eefc134 100644
--- a/src/chasers/chaser_snapshot.cpp
+++ b/src/chasers/chaser_snapshot.cpp
@@ -52,8 +52,6 @@ chaser_snapshot::chaser_snapshot(full_node& node) NOEXCEPT
 
 code chaser_snapshot::start() NOEXCEPT
 {
-    BC_ASSERT(stranded());
-
     // Initial values assume all stops or starts are snapped.
     // get_top_validated is an expensive scan.
 
diff --git a/src/chasers/chaser_storage.cpp b/src/chasers/chaser_storage.cpp
index 306caa45..7abbd33d 100644
--- a/src/chasers/chaser_storage.cpp
+++ b/src/chasers/chaser_storage.cpp
@@ -47,8 +47,6 @@ chaser_storage::chaser_storage(full_node& node) NOEXCEPT
 
 code chaser_storage::start() NOEXCEPT
 {
-    BC_ASSERT(stranded());
-
     // Construct is too early to create the unstarted timer.
     disk_timer_ = std::make_shared<deadline>(log, strand(), seconds{1});
 
diff --git a/src/chasers/chaser_template.cpp b/src/chasers/chaser_template.cpp
index 80d45e03..b6aa2077 100644
--- a/src/chasers/chaser_template.cpp
+++ b/src/chasers/chaser_template.cpp
@@ -43,7 +43,6 @@ chaser_template::chaser_template(full_node& node) NOEXCEPT
 // TODO: initialize template state.
 code chaser_template::start() NOEXCEPT
 {
-    BC_ASSERT(stranded());
     SUBSCRIBE_CHASE(handle_chase, _1, _2, _3);
     return error::success;
 }
diff --git a/src/chasers/chaser_transaction.cpp b/src/chasers/chaser_transaction.cpp
index 347a5336..ee6a5fcb 100644
--- a/src/chasers/chaser_transaction.cpp
+++ b/src/chasers/chaser_transaction.cpp
@@ -43,7 +43,6 @@ chaser_transaction::chaser_transaction(full_node& node) NOEXCEPT
 // TODO: initialize tx graph from store, log and stop on error.
 code chaser_transaction::start() NOEXCEPT
 {
-    BC_ASSERT(stranded());
     SUBSCRIBE_CHASE(handle_chase, _1, _2, _3);
     return error::success;
 }
diff --git a/src/error.cpp b/src/error.cpp
index 33fafa00..173935ea 100644
--- a/src/error.cpp
+++ b/src/error.cpp
@@ -88,6 +88,7 @@ DEFINE_ERROR_T_MESSAGE_MAP(error)
     { confirm10, "confirm10" },
     { confirm11, "confirm11" },
     { confirm12, "confirm12" },
+    { estimate_failed, "estimate_failed" },
     { estimates_failed, "estimates_failed" },
     { estimates_disabled, "estimates_disabled" },
     { estimates_premature, "estimates_premature" }
diff --git a/test/error.cpp b/test/error.cpp
index cb4699ba..9b385bbc 100644
--- a/test/error.cpp
+++ b/test/error.cpp
@@ -225,6 +225,15 @@ BOOST_AUTO_TEST_CASE(error_t__code__confirm1__true_expected_message)
     BOOST_REQUIRE_EQUAL(ec.message(), "confirm1");
 }
 
+BOOST_AUTO_TEST_CASE(error_t__code__estimate_failed__true_expected_message)
+{
+    constexpr auto value = error::estimate_failed;
+    const auto ec = code(value);
+    BOOST_REQUIRE(ec);
+    BOOST_REQUIRE(ec == value);
+    BOOST_REQUIRE_EQUAL(ec.message(), "estimate_failed");
+}
+
 BOOST_AUTO_TEST_CASE(error_t__code__estimates_failed__true_expected_message)
 {
     constexpr auto value = error::estimates_failed;