diff --git a/editor/CMakeLists.txt b/editor/CMakeLists.txt
index fb9c475..2491350 100644
--- a/editor/CMakeLists.txt
+++ b/editor/CMakeLists.txt
@@ -2130,4 +2130,8 @@ add_executable(step358_test tests/step358_test.cpp)
 target_include_directories(step358_test PRIVATE src)
 target_link_libraries(step358_test PRIVATE nlohmann_json::nlohmann_json)
 
+add_executable(step359_test tests/step359_test.cpp)
+target_include_directories(step359_test PRIVATE src)
+target_link_libraries(step359_test PRIVATE nlohmann_json::nlohmann_json)
+
 # Step 12: Dear ImGui shell scaffolding created (main.cpp exists but not built due to dependencies)
diff --git a/editor/src/panels/FindReplaceBar.h b/editor/src/panels/FindReplaceBar.h
new file mode 100644
index 0000000..d3595d1
--- /dev/null
+++ b/editor/src/panels/FindReplaceBar.h
@@ -0,0 +1,162 @@
+#pragma once
+// Step 359: Find/replace bar model with in-file and project search.
+
+#include <string>
+#include <utility>
+#include <vector>
+
+struct FindMatch {
+    int start = -1;
+    int end = -1;
+    int line = 1;
+    int column = 1;
+};
+
+struct ProjectFindResult {
+    std::string filePath;
+    int line = 1;
+    int column = 1;
+    std::string preview;
+};
+
+class FindReplaceBar {
+public:
+    void openFind() {
+        visible_ = true;
+        replaceMode_ = false;
+    }
+
+    void openReplace() {
+        visible_ = true;
+        replaceMode_ = true;
+    }
+
+    void close() {
+        visible_ = false;
+    }
+
+    bool isVisible() const { return visible_; }
+    bool isReplaceMode() const { return replaceMode_; }
+
+    void setQuery(const std::string& query, const std::string& text) {
+        query_ = query;
+        rebuildMatches(text);
+    }
+
+    void setReplaceText(const std::string& repl) { replaceText_ = repl; }
+
+    const std::string& query() const { return query_; }
+    const std::string& replaceText() const { return replaceText_; }
+
+    const std::vector<FindMatch>& matches() const { return matches_; }
+
+    int matchCount() const { return static_cast<int>(matches_.size()); }
+    int currentIndex() const { return currentIndex_; }
+
+    bool hasHighlights() const { return !matches_.empty(); }
+
+    std::string matchCounterText() const {
+        if (matches_.empty()) return "0 of 0";
+        return std::to_string(currentIndex_ + 1) + " of " + std::to_string(matches_.size());
+    }
+
+    void nextMatch() {
+        if (matches_.empty()) return;
+        currentIndex_ = (currentIndex_ + 1) % static_cast<int>(matches_.size());
+    }
+
+    void prevMatch() {
+        if (matches_.empty()) return;
+        currentIndex_ = (currentIndex_ - 1 + static_cast<int>(matches_.size())) %
+                        static_cast<int>(matches_.size());
+    }
+
+    bool replaceCurrent(std::string& text) {
+        if (matches_.empty() || currentIndex_ < 0 || currentIndex_ >= (int)matches_.size()) return false;
+        const auto m = matches_[currentIndex_];
+        text.replace(m.start, m.end - m.start, replaceText_);
+        rebuildMatches(text);
+        return true;
+    }
+
+    int replaceAll(std::string& text) {
+        if (query_.empty()) return 0;
+        int replaced = 0;
+        size_t pos = 0;
+        while (true) {
+            size_t found = text.find(query_, pos);
+            if (found == std::string::npos) break;
+            text.replace(found, query_.size(), replaceText_);
+            pos = found + replaceText_.size();
+            replaced++;
+        }
+        rebuildMatches(text);
+        return replaced;
+    }
+
+    std::vector<ProjectFindResult> searchProject(
+        const std::vector<std::pair<std::string, std::string>>& files) const {
+        std::vector<ProjectFindResult> out;
+        if (query_.empty()) return out;
+        for (const auto& [path, content] : files) {
+            int line = 1;
+            int col = 1;
+            for (size_t i = 0; i < content.size(); ++i) {
+                if (i + query_.size() <= content.size() &&
+                    content.compare(i, query_.size(), query_) == 0) {
+                    ProjectFindResult r;
+                    r.filePath = path;
+                    r.line = line;
+                    r.column = col;
+                    size_t previewStart = i > 10 ? i - 10 : 0;
+                    size_t previewLen = std::min<size_t>(40, content.size() - previewStart);
+                    r.preview = content.substr(previewStart, previewLen);
+                    out.push_back(r);
+                }
+                if (content[i] == '\n') {
+                    line++;
+                    col = 1;
+                } else {
+                    col++;
+                }
+            }
+        }
+        return out;
+    }
+
+private:
+    void rebuildMatches(const std::string& text) {
+        matches_.clear();
+        currentIndex_ = 0;
+        if (query_.empty()) {
+            currentIndex_ = -1;
+            return;
+        }
+        int line = 1;
+        int col = 1;
+        for (size_t i = 0; i + query_.size() <= text.size(); ++i) {
+            if (text.compare(i, query_.size(), query_) == 0) {
+                FindMatch m;
+                m.start = static_cast<int>(i);
+                m.end = static_cast<int>(i + query_.size());
+                m.line = line;
+                m.column = col;
+                matches_.push_back(m);
+            }
+            if (text[i] == '\n') {
+                line++;
+                col = 1;
+            } else {
+                col++;
+            }
+        }
+        if (matches_.empty()) currentIndex_ = -1;
+    }
+
+    bool visible_ = false;
+    bool replaceMode_ = false;
+    std::string query_;
+    std::string replaceText_;
+    std::vector<FindMatch> matches_;
+    int currentIndex_ = -1;
+};
diff --git a/editor/tests/step359_test.cpp b/editor/tests/step359_test.cpp
new file mode 100644
index 0000000..ce43d90
--- /dev/null
+++ b/editor/tests/step359_test.cpp
@@ -0,0 +1,157 @@
+// Step 359: Find and Replace Improvements (12 tests)
+
+#include <cassert>
+#include <iostream>
+#include <string>
+#include <vector>
+#include "panels/FindReplaceBar.h"
+
+int main() {
+    int passed = 0;
+    const std::string text = "alpha beta\nbeta gamma\nbeta\n";
+
+    // Test 1: Ctrl+F opens find bar
+    {
+        FindReplaceBar bar;
+        bar.openFind();
+        assert(bar.isVisible());
+        assert(!bar.isReplaceMode());
+        std::cout << "Test 1 PASSED: open find bar\n";
+        passed++;
+    }
+
+    // Test 2: typing filters matches
+    {
+        FindReplaceBar bar;
+        bar.openFind();
+        bar.setQuery("beta", text);
+        assert(bar.matchCount() == 3);
+        std::cout << "Test 2 PASSED: typing filters matches\n";
+        passed++;
+    }
+
+    // Test 3: match highlighting visible
+    {
+        FindReplaceBar bar;
+        bar.openFind();
+        bar.setQuery("beta", text);
+        assert(bar.hasHighlights());
+        std::cout << "Test 3 PASSED: highlights visible\n";
+        passed++;
+    }
+
+    // Test 4: match count accurate
+    {
+        FindReplaceBar bar;
+        bar.openFind();
+        bar.setQuery("beta", text);
+        assert(bar.matchCounterText() == "1 of 3");
+        std::cout << "Test 4 PASSED: match count text\n";
+        passed++;
+    }
+
+    // Test 5: Enter cycles through matches (next)
+    {
+        FindReplaceBar bar;
+        bar.openFind();
+        bar.setQuery("beta", text);
+        int start = bar.currentIndex();
+        bar.nextMatch();
+        assert(bar.currentIndex() != start);
+        std::cout << "Test 5 PASSED: next match cycle\n";
+        passed++;
+    }
+
+    // Test 6: Ctrl+H shows replace field
+    {
+        FindReplaceBar bar;
+        bar.openReplace();
+        assert(bar.isVisible());
+        assert(bar.isReplaceMode());
+        std::cout << "Test 6 PASSED: replace mode open\n";
+        passed++;
+    }
+
+    // Test 7: replace works
+    {
+        FindReplaceBar bar;
+        std::string mutableText = text;
+        bar.openReplace();
+        bar.setQuery("gamma", mutableText);
+        bar.setReplaceText("delta");
+        bool ok = bar.replaceCurrent(mutableText);
+        assert(ok);
+        assert(mutableText.find("delta") != std::string::npos);
+        std::cout << "Test 7 PASSED: replace current\n";
+        passed++;
+    }
+
+    // Test 8: project-wide search returns results
+    {
+        FindReplaceBar bar;
+        bar.openFind();
+        bar.setQuery("beta", text);
+        std::vector<std::pair<std::string, std::string>> files = {
+            {"a.txt", text},
+            {"b.txt", "zzz\nbeta\n"}
+        };
+        auto results = bar.searchProject(files);
+        assert(results.size() == 4);
+        std::cout << "Test 8 PASSED: project search results\n";
+        passed++;
+    }
+
+    // Test 9: Escape closes find bar
+    {
+        FindReplaceBar bar;
+        bar.openFind();
+        bar.close();
+        assert(!bar.isVisible());
+        std::cout << "Test 9 PASSED: close find bar\n";
+        passed++;
+    }
+
+    // Test 10: empty search clears highlights
+    {
+        FindReplaceBar bar;
+        bar.openFind();
+        bar.setQuery("beta", text);
+        assert(bar.hasHighlights());
+        bar.setQuery("", text);
+        assert(!bar.hasHighlights());
+        assert(bar.matchCount() == 0);
+        std::cout << "Test 10 PASSED: empty query clears highlights\n";
+        passed++;
+    }
+
+    // Test 11: Shift+Enter cycles previous match
+    {
+        FindReplaceBar bar;
+        bar.openFind();
+        bar.setQuery("beta", text);
+        bar.nextMatch(); // index 1
+        int idx = bar.currentIndex();
+        bar.prevMatch();
+        assert(bar.currentIndex() != idx);
+        std::cout << "Test 11 PASSED: previous match cycle\n";
+        passed++;
+    }
+
+    // Test 12: replace-all updates count and clears matches when fully replaced
+    {
+        FindReplaceBar bar;
+        std::string mutableText = text;
+        bar.openReplace();
+        bar.setQuery("beta", mutableText);
+        bar.setReplaceText("B");
+        int replaced = bar.replaceAll(mutableText);
+        assert(replaced == 3);
+        assert(mutableText.find("beta") == std::string::npos);
+        std::cout << "Test 12 PASSED: replace all\n";
+        passed++;
+    }
+
+    std::cout << "\nResults: " << passed << "/12\n";
+    assert(passed == 12);
+    return 0;
+}
diff --git a/progress.md b/progress.md
index d5d4d3d..01e6c34 100644
--- a/progress.md
+++ b/progress.md
@@ -1971,6 +1971,42 @@ and go-to-definition lookup with current-file preference and cross-file fallback
 - `step357_test` — PASS (12/12) regression coverage
 - `step358_test` — PASS (12/12) new step coverage
 
+### Step 359: Find and Replace Improvements
+**Status:** PASS (12/12 tests)
+
+Implemented a find/replace bar model with in-file match tracking, current-match
+navigation, replace-current/replace-all flows, and project-wide search results.
+Model behavior includes open/close modes, highlight state, and match counter text.
+
+**Files created:**
+- `editor/src/panels/FindReplaceBar.h` — find/replace model:
+  - find/replace visibility + mode toggles
+  - query + match indexing + counter text
+  - next/previous match navigation
+  - replace-current and replace-all operations
+  - project-wide search result generation
+- `editor/tests/step359_test.cpp` — 12 tests covering:
+  1. open find
+  2. query-to-match filtering
+  3. highlight visibility
+  4. match counter formatting
+  5. next-match cycling
+  6. replace mode open
+  7. replace-current operation
+  8. project search results
+  9. close behavior
+  10. empty-query clears highlights
+  11. previous-match cycling
+  12. replace-all behavior
+
+**Files modified:**
+- `editor/CMakeLists.txt` — `step359_test` target
+
+**Verification run:**
+- `step357_test` — PASS (12/12) regression coverage
+- `step358_test` — PASS (12/12) regression coverage
+- `step359_test` — PASS (12/12) new step coverage
+
 # Roadmap Planning — Sprints 12-25+
 
 ## Status: Planning Complete (Sprints 12-19 detailed, 20-25 in roadmap.md)