diff --git a/editor/CMakeLists.txt b/editor/CMakeLists.txt
index 8e53f1b..b13158b 100644
--- a/editor/CMakeLists.txt
+++ b/editor/CMakeLists.txt
@@ -7364,3 +7364,44 @@ target_link_libraries(step867_test PRIVATE nlohmann_json::nlohmann_json unoffici
 add_executable(step868_test tests/step868_test.cpp)
 target_include_directories(step868_test PRIVATE src)
 target_link_libraries(step868_test PRIVATE nlohmann_json::nlohmann_json unofficial::tree-sitter::tree-sitter tree_sitter_python tree_sitter_cpp tree_sitter_elisp tree_sitter_javascript tree_sitter_typescript tree_sitter_java tree_sitter_rust tree_sitter_go)
+
+# Sprint 64: Cost-Aware Transpilation Planning (Steps 869-878)
+add_executable(step869_test tests/step869_test.cpp)
+target_include_directories(step869_test PRIVATE src)
+target_link_libraries(step869_test PRIVATE nlohmann_json::nlohmann_json unofficial::tree-sitter::tree-sitter tree_sitter_python tree_sitter_cpp tree_sitter_elisp tree_sitter_javascript tree_sitter_typescript tree_sitter_java tree_sitter_rust tree_sitter_go)
+
+add_executable(step870_test tests/step870_test.cpp)
+target_include_directories(step870_test PRIVATE src)
+target_link_libraries(step870_test PRIVATE nlohmann_json::nlohmann_json unofficial::tree-sitter::tree-sitter tree_sitter_python tree_sitter_cpp tree_sitter_elisp tree_sitter_javascript tree_sitter_typescript tree_sitter_java tree_sitter_rust tree_sitter_go)
+
+add_executable(step871_test tests/step871_test.cpp)
+target_include_directories(step871_test PRIVATE src)
+target_link_libraries(step871_test PRIVATE nlohmann_json::nlohmann_json unofficial::tree-sitter::tree-sitter tree_sitter_python tree_sitter_cpp tree_sitter_elisp tree_sitter_javascript tree_sitter_typescript tree_sitter_java tree_sitter_rust tree_sitter_go)
+
+add_executable(step872_test tests/step872_test.cpp)
+target_include_directories(step872_test PRIVATE src)
+target_link_libraries(step872_test PRIVATE nlohmann_json::nlohmann_json unofficial::tree-sitter::tree-sitter tree_sitter_python tree_sitter_cpp tree_sitter_elisp tree_sitter_javascript tree_sitter_typescript tree_sitter_java tree_sitter_rust tree_sitter_go)
+
+add_executable(step873_test tests/step873_test.cpp)
+target_include_directories(step873_test PRIVATE src)
+target_link_libraries(step873_test PRIVATE nlohmann_json::nlohmann_json unofficial::tree-sitter::tree-sitter tree_sitter_python tree_sitter_cpp tree_sitter_elisp tree_sitter_javascript tree_sitter_typescript tree_sitter_java tree_sitter_rust tree_sitter_go)
+
+add_executable(step874_test tests/step874_test.cpp)
+target_include_directories(step874_test PRIVATE src)
+target_link_libraries(step874_test PRIVATE nlohmann_json::nlohmann_json unofficial::tree-sitter::tree-sitter tree_sitter_python tree_sitter_cpp tree_sitter_elisp tree_sitter_javascript tree_sitter_typescript tree_sitter_java tree_sitter_rust tree_sitter_go)
+
+add_executable(step875_test tests/step875_test.cpp)
+target_include_directories(step875_test PRIVATE src)
+target_link_libraries(step875_test PRIVATE nlohmann_json::nlohmann_json unofficial::tree-sitter::tree-sitter tree_sitter_python tree_sitter_cpp tree_sitter_elisp tree_sitter_javascript tree_sitter_typescript tree_sitter_java tree_sitter_rust tree_sitter_go)
+
+add_executable(step876_test tests/step876_test.cpp)
+target_include_directories(step876_test PRIVATE src)
+target_link_libraries(step876_test PRIVATE nlohmann_json::nlohmann_json unofficial::tree-sitter::tree-sitter tree_sitter_python tree_sitter_cpp tree_sitter_elisp tree_sitter_javascript tree_sitter_typescript tree_sitter_java tree_sitter_rust tree_sitter_go)
+
+add_executable(step877_test tests/step877_test.cpp)
+target_include_directories(step877_test PRIVATE src)
+target_link_libraries(step877_test PRIVATE nlohmann_json::nlohmann_json unofficial::tree-sitter::tree-sitter tree_sitter_python tree_sitter_cpp tree_sitter_elisp tree_sitter_javascript tree_sitter_typescript tree_sitter_java tree_sitter_rust tree_sitter_go)
+
+add_executable(step878_test tests/step878_test.cpp)
+target_include_directories(step878_test PRIVATE src)
+target_link_libraries(step878_test PRIVATE nlohmann_json::nlohmann_json unofficial::tree-sitter::tree-sitter tree_sitter_python tree_sitter_cpp tree_sitter_elisp tree_sitter_javascript tree_sitter_typescript tree_sitter_java tree_sitter_rust tree_sitter_go)
diff --git a/editor/src/MCPServer.h b/editor/src/MCPServer.h
index f21a998..5ef66fe 100644
--- a/editor/src/MCPServer.h
+++ b/editor/src/MCPServer.h
@@ -735,4 +735,8 @@ private:
 #include "mcp/RegisterFailureTelemetryTools.h"
 #include "graduation/HintModelInterface.h"
 #include "mcp/RegisterAdapterHintsTools.h"
+#include "graduation/PortingCostModel.h"
+#include "graduation/MultiPlanAlternativeGenerator.h"
+#include "graduation/BudgetPolicyEnforcer.h"
+#include "mcp/RegisterCostPlanningTools.h"
 #include "mcp/RegisterOnboardingAndAllTools.h"
diff --git a/editor/src/Sprint64IntegrationSummary.h b/editor/src/Sprint64IntegrationSummary.h
new file mode 100644
index 0000000..03f1e01
--- /dev/null
+++ b/editor/src/Sprint64IntegrationSummary.h
@@ -0,0 +1,25 @@
+#pragma once
+// Step 878: Sprint 64 integration summary — Cost-Aware Transpilation Planning
+#include <string>
+#include <nlohmann/json.hpp>
+
+struct Sprint64IntegrationSummary {
+    static constexpr int sprintNumber = 64;
+    static constexpr int stepsCompleted = 10;
+    static constexpr const char* theme = "Cost-Aware Transpilation Planning";
+
+    static bool verify() {
+        return sprintNumber == 64 && stepsCompleted == 10;
+    }
+
+    static nlohmann::json toJson() {
+        return {
+            {"sprint", sprintNumber},
+            {"steps", stepsCompleted},
+            {"theme", theme},
+            {"status", "complete"},
+            {"tools_added", {"whetstone_plan_transpilation_run", "whetstone_estimate_porting_cost"}},
+            {"policy_rule", "Over-budget plans require explicit reviewer approval token."}
+        };
+    }
+};
diff --git a/editor/src/graduation/BudgetPolicyEnforcer.h b/editor/src/graduation/BudgetPolicyEnforcer.h
new file mode 100644
index 0000000..1e8974a
--- /dev/null
+++ b/editor/src/graduation/BudgetPolicyEnforcer.h
@@ -0,0 +1,52 @@
+#pragma once
+// Step 873: Budget policy enforcer.
+#include <string>
+#include <nlohmann/json.hpp>
+
+struct BudgetPolicy {
+    float maxTotalCost = 1.0f;
+    bool requireApprovalTokenForOverage = true;
+};
+
+struct BudgetEnforcementResult {
+    std::string pairId;
+    bool withinBudget = false;
+    bool requiresApprovalToken = false;
+    float requestedCost = 0.0f;
+    float budgetLimit = 0.0f;
+    std::string decision; // "approved", "requires_token", "rejected"
+};
+
+class BudgetPolicyEnforcer {
+public:
+    static BudgetEnforcementResult enforce(const std::string& pairId,
+                                             float requestedCost,
+                                             const BudgetPolicy& policy,
+                                             bool hasApprovalToken = false) {
+        BudgetEnforcementResult r;
+        r.pairId = pairId;
+        r.requestedCost = requestedCost;
+        r.budgetLimit = policy.maxTotalCost;
+        r.withinBudget = requestedCost <= policy.maxTotalCost;
+        if (r.withinBudget) {
+            r.decision = "approved";
+        } else if (policy.requireApprovalTokenForOverage && hasApprovalToken) {
+            r.requiresApprovalToken = false;
+            r.decision = "approved";
+        } else if (policy.requireApprovalTokenForOverage) {
+            r.requiresApprovalToken = true;
+            r.decision = "requires_token";
+        } else {
+            r.decision = "rejected";
+        }
+        return r;
+    }
+
+    static nlohmann::json toJson(const BudgetEnforcementResult& r) {
+        return {{"pair_id", r.pairId}, {"within_budget", r.withinBudget},
+                {"requires_approval_token", r.requiresApprovalToken},
+                {"requested_cost", r.requestedCost},
+                {"budget_limit", r.budgetLimit},
+                {"decision", r.decision}};
+    }
+};
diff --git a/editor/src/graduation/ComputeCostEstimator.h b/editor/src/graduation/ComputeCostEstimator.h
new file mode 100644
index 0000000..a407553
--- /dev/null
+++ b/editor/src/graduation/ComputeCostEstimator.h
@@ -0,0 +1,48 @@
+#pragma once
+// Step 871: Compute/runtime cost estimator from prior runs.
+#include <string>
+#include <vector>
+#include <nlohmann/json.hpp>
+
+struct PriorRunRecord {
+    std::string pairId;
+    int durationMs = 0;
+    int tokenCount = 0;
+};
+
+struct ComputeCostEstimate {
+    std::string pairId;
+    float estimatedDurationMs = 0.0f;
+    float estimatedTokens = 0.0f;
+    int sampleCount = 0;
+    bool hasHistory = false;
+};
+
+class ComputeCostEstimator {
+public:
+    static ComputeCostEstimate estimate(const std::string& pairId,
+                                         const std::vector<PriorRunRecord>& history) {
+        ComputeCostEstimate e;
+        e.pairId = pairId;
+        e.sampleCount = static_cast<int>(history.size());
+        e.hasHistory = !history.empty();
+        if (e.hasHistory) {
+            float sumDur = 0, sumTok = 0;
+            for (const auto& r : history) {
+                sumDur += r.durationMs;
+                sumTok += r.tokenCount;
+            }
+            e.estimatedDurationMs = sumDur / e.sampleCount;
+            e.estimatedTokens = sumTok / e.sampleCount;
+        }
+        return e;
+    }
+
+    static nlohmann::json toJson(const ComputeCostEstimate& e) {
+        return {{"pair_id", e.pairId},
+                {"estimated_duration_ms", e.estimatedDurationMs},
+                {"estimated_tokens", e.estimatedTokens},
+                {"sample_count", e.sampleCount},
+                {"has_history", e.hasHistory}};
+    }
+};
diff --git a/editor/src/graduation/CostQualityTradeoffReport.h b/editor/src/graduation/CostQualityTradeoffReport.h
new file mode 100644
index 0000000..6b9d1bc
--- /dev/null
+++ b/editor/src/graduation/CostQualityTradeoffReport.h
@@ -0,0 +1,48 @@
+#pragma once
+// Step 874: Cost-vs-quality tradeoff report generator.
+#include <string>
+#include <vector>
+#include <nlohmann/json.hpp>
+
+struct TradeoffEntry {
+    std::string profile;
+    float cost = 0.0f;
+    float quality = 0.0f;
+    float efficiency = 0.0f; // quality / cost
+};
+
+struct CostQualityReport {
+    std::string pairId;
+    std::vector<TradeoffEntry> entries;
+    std::string recommendedProfile;
+};
+
+class CostQualityTradeoffReport {
+public:
+    static CostQualityReport generate(const std::string& pairId,
+                                       const std::vector<std::pair<std::string,float>>& planCosts,
+                                       const std::vector<std::pair<std::string,float>>& planQualities) {
+        CostQualityReport r;
+        r.pairId = pairId;
+        float bestEff = -1.0f;
+        for (size_t i = 0; i < planCosts.size() && i < planQualities.size(); ++i) {
+            TradeoffEntry e;
+            e.profile = planCosts[i].first;
+            e.cost = planCosts[i].second;
+            e.quality = planQualities[i].second;
+            e.efficiency = (e.cost > 0.0f) ? e.quality / e.cost : 0.0f;
+            r.entries.push_back(e);
+            if (e.efficiency > bestEff) { bestEff = e.efficiency; r.recommendedProfile = e.profile; }
+        }
+        return r;
+    }
+
+    static nlohmann::json toJson(const CostQualityReport& r) {
+        nlohmann::json arr = nlohmann::json::array();
+        for (const auto& e : r.entries)
+            arr.push_back({{"profile", e.profile}, {"cost", e.cost},
+                           {"quality", e.quality}, {"efficiency", e.efficiency}});
+        return {{"pair_id", r.pairId}, {"entries", arr},
+                {"recommended_profile", r.recommendedProfile}};
+    }
+};
diff --git a/editor/src/graduation/CostTelemetryIntegration.h b/editor/src/graduation/CostTelemetryIntegration.h
new file mode 100644
index 0000000..5c8d0db
--- /dev/null
+++ b/editor/src/graduation/CostTelemetryIntegration.h
@@ -0,0 +1,55 @@
+#pragma once
+// Step 877: Cost telemetry integration in metrics stack.
+#include <string>
+#include <vector>
+#include <nlohmann/json.hpp>
+
+struct CostTelemetryRecord {
+    std::string pairId;
+    std::string profile;
+    float actualCost = 0.0f;
+    float estimatedCost = 0.0f;
+    float costError = 0.0f; // |actual - estimated|
+    bool overBudget = false;
+};
+
+class CostTelemetryIntegration {
+public:
+    void record(const CostTelemetryRecord& r) {
+        records_.push_back(r);
+    }
+
+    float averageCostError() const {
+        if (records_.empty()) return 0.0f;
+        float sum = 0.0f;
+        for (const auto& r : records_) sum += r.costError;
+        return sum / records_.size();
+    }
+
+    int overBudgetCount() const {
+        int n = 0;
+        for (const auto& r : records_) if (r.overBudget) ++n;
+        return n;
+    }
+
+    static CostTelemetryRecord make(const std::string& pairId, const std::string& profile,
+                                     float actual, float estimated) {
+        CostTelemetryRecord r;
+        r.pairId = pairId;
+        r.profile = profile;
+        r.actualCost = actual;
+        r.estimatedCost = estimated;
+        r.costError = std::abs(actual - estimated);
+        r.overBudget = actual > 1.0f;
+        return r;
+    }
+
+    static nlohmann::json toJson(const CostTelemetryRecord& r) {
+        return {{"pair_id", r.pairId}, {"profile", r.profile},
+                {"actual_cost", r.actualCost}, {"estimated_cost", r.estimatedCost},
+                {"cost_error", r.costError}, {"over_budget", r.overBudget}};
+    }
+
+private:
+    std::vector<CostTelemetryRecord> records_;
+};
diff --git a/editor/src/graduation/MultiPlanAlternativeGenerator.h b/editor/src/graduation/MultiPlanAlternativeGenerator.h
new file mode 100644
index 0000000..ff5fe6f
--- /dev/null
+++ b/editor/src/graduation/MultiPlanAlternativeGenerator.h
@@ -0,0 +1,33 @@
+#pragma once
+// Step 872: Multi-plan alternative generator.
+#include <string>
+#include <vector>
+#include <nlohmann/json.hpp>
+
+struct TranspilationPlanAlternative {
+    std::string planId;
+    std::string profile; // "cheap", "balanced", "rigorous"
+    float estimatedCost = 0.0f;
+    float estimatedQuality = 0.0f;
+    bool requiresReview = false;
+};
+
+class MultiPlanAlternativeGenerator {
+public:
+    static std::vector<TranspilationPlanAlternative> generate(
+            const std::string& pairId, float baseCost) {
+        (void)pairId;
+        std::vector<TranspilationPlanAlternative> plans;
+        plans.push_back({"plan-cheap",     "cheap",     baseCost * 0.5f, 0.6f, false});
+        plans.push_back({"plan-balanced",  "balanced",  baseCost,        0.8f, false});
+        plans.push_back({"plan-rigorous",  "rigorous",  baseCost * 2.0f, 0.95f, true});
+        return plans;
+    }
+
+    static nlohmann::json toJson(const TranspilationPlanAlternative& p) {
+        return {{"plan_id", p.planId}, {"profile", p.profile},
+                {"estimated_cost", p.estimatedCost},
+                {"estimated_quality", p.estimatedQuality},
+                {"requires_review", p.requiresReview}};
+    }
+};
diff --git a/editor/src/graduation/PortingCostModel.h b/editor/src/graduation/PortingCostModel.h
new file mode 100644
index 0000000..3c9bf0d
--- /dev/null
+++ b/editor/src/graduation/PortingCostModel.h
@@ -0,0 +1,34 @@
+#pragma once
+// Step 869: Porting cost model v1.
+#include <string>
+#include <nlohmann/json.hpp>
+
+struct PortingCostEstimate {
+    std::string pairId;
+    float computeCost = 0.0f;   // normalized 0-1
+    float reviewCost = 0.0f;    // normalized 0-1
+    float totalCost = 0.0f;
+    std::string tier;           // "low", "medium", "high"
+};
+
+class PortingCostModel {
+public:
+    static PortingCostEstimate estimate(const std::string& pairId,
+                                        int linesOfCode, float ambiguityScore) {
+        PortingCostEstimate e;
+        e.pairId = pairId;
+        e.computeCost = std::min(1.0f, linesOfCode / 1000.0f);
+        e.reviewCost = std::min(1.0f, ambiguityScore);
+        e.totalCost = (e.computeCost + e.reviewCost) / 2.0f;
+        if (e.totalCost < 0.33f)      e.tier = "low";
+        else if (e.totalCost < 0.66f) e.tier = "medium";
+        else                          e.tier = "high";
+        return e;
+    }
+
+    static nlohmann::json toJson(const PortingCostEstimate& e) {
+        return {{"pair_id", e.pairId}, {"compute_cost", e.computeCost},
+                {"review_cost", e.reviewCost}, {"total_cost", e.totalCost},
+                {"tier", e.tier}};
+    }
+};
diff --git a/editor/src/graduation/ReviewEffortEstimator.h b/editor/src/graduation/ReviewEffortEstimator.h
new file mode 100644
index 0000000..d22a626
--- /dev/null
+++ b/editor/src/graduation/ReviewEffortEstimator.h
@@ -0,0 +1,37 @@
+#pragma once
+// Step 870: Review effort estimator from ambiguity/risk packets.
+#include <string>
+#include <nlohmann/json.hpp>
+
+struct ReviewEffortPacket {
+    std::string pairId;
+    float ambiguity = 0.0f;
+    float riskScore = 0.0f;
+    int estimatedReviewMinutes = 0;
+    std::string complexityLabel; // "trivial", "simple", "moderate", "complex"
+};
+
+class ReviewEffortEstimator {
+public:
+    static ReviewEffortPacket estimate(const std::string& pairId,
+                                        float ambiguity, float riskScore) {
+        ReviewEffortPacket p;
+        p.pairId = pairId;
+        p.ambiguity = ambiguity;
+        p.riskScore = riskScore;
+        float combined = (ambiguity + riskScore) / 2.0f;
+        p.estimatedReviewMinutes = static_cast<int>(combined * 60.0f) + 5;
+        if (combined < 0.2f)      p.complexityLabel = "trivial";
+        else if (combined < 0.4f) p.complexityLabel = "simple";
+        else if (combined < 0.7f) p.complexityLabel = "moderate";
+        else                      p.complexityLabel = "complex";
+        return p;
+    }
+
+    static nlohmann::json toJson(const ReviewEffortPacket& p) {
+        return {{"pair_id", p.pairId}, {"ambiguity", p.ambiguity},
+                {"risk_score", p.riskScore},
+                {"estimated_review_minutes", p.estimatedReviewMinutes},
+                {"complexity_label", p.complexityLabel}};
+    }
+};
diff --git a/editor/src/mcp/RegisterCostPlanningTools.h b/editor/src/mcp/RegisterCostPlanningTools.h
new file mode 100644
index 0000000..cf80e36
--- /dev/null
+++ b/editor/src/mcp/RegisterCostPlanningTools.h
@@ -0,0 +1,62 @@
+// Sprint 64: Cost-Aware Transpilation Planning MCP tools (Steps 875-876)
+// Included inside MCPServer class body.
+
+    void registerCostPlanningTools() {
+        tools_.push_back({"whetstone_plan_transpilation_run",
+            "Generate cost-aware plan alternatives for a transpilation run.",
+            {{"type", "object"}, {"properties", {
+                {"pair_id", {{"type", "string"}}},
+                {"lines_of_code", {{"type", "integer"}}},
+                {"ambiguity_score", {{"type", "number"}}},
+                {"budget_limit", {{"type", "number"}}}
+            }}, {"required", nlohmann::json::array({"pair_id"})}}
+        });
+        toolHandlers_["whetstone_plan_transpilation_run"] =
+            [this](const nlohmann::json& args) { return runPlanTranspilationRun(args); };
+
+        tools_.push_back({"whetstone_estimate_porting_cost",
+            "Estimate porting cost for a pair from LOC and ambiguity score.",
+            {{"type", "object"}, {"properties", {
+                {"pair_id", {{"type", "string"}}},
+                {"lines_of_code", {{"type", "integer"}}},
+                {"ambiguity_score", {{"type", "number"}}}
+            }}, {"required", nlohmann::json::array({"pair_id"})}}
+        });
+        toolHandlers_["whetstone_estimate_porting_cost"] =
+            [this](const nlohmann::json& args) { return runEstimatePortingCost(args); };
+    }
+
+    nlohmann::json runPlanTranspilationRun(const nlohmann::json& args) {
+        if (!args.is_object()) return {{"success", false}, {"error", "pair_id required"}};
+        std::string pairId = args.value("pair_id", "");
+        if (pairId.empty()) return {{"success", false}, {"error", "pair_id required"}};
+        int loc = args.value("lines_of_code", 100);
+        float ambiguity = args.value("ambiguity_score", 0.3f);
+        float budgetLimit = args.value("budget_limit", 1.0f);
+        auto costEst = PortingCostModel::estimate(pairId, loc, ambiguity);
+        auto plans = MultiPlanAlternativeGenerator::generate(pairId, costEst.totalCost);
+        BudgetPolicy pol{budgetLimit, true};
+        nlohmann::json planArr = nlohmann::json::array();
+        for (const auto& plan : plans) {
+            auto enforcement = BudgetPolicyEnforcer::enforce(pairId, plan.estimatedCost, pol);
+            auto pj = MultiPlanAlternativeGenerator::toJson(plan);
+            pj["budget_decision"] = enforcement.decision;
+            planArr.push_back(pj);
+        }
+        return {{"success", true}, {"pair_id", pairId},
+                {"base_cost_tier", costEst.tier},
+                {"plans", planArr},
+                {"plan_count", (int)plans.size()}};
+    }
+
+    nlohmann::json runEstimatePortingCost(const nlohmann::json& args) {
+        if (!args.is_object()) return {{"success", false}, {"error", "pair_id required"}};
+        std::string pairId = args.value("pair_id", "");
+        if (pairId.empty()) return {{"success", false}, {"error", "pair_id required"}};
+        int loc = args.value("lines_of_code", 100);
+        float ambiguity = args.value("ambiguity_score", 0.3f);
+        auto est = PortingCostModel::estimate(pairId, loc, ambiguity);
+        auto j = PortingCostModel::toJson(est);
+        j["success"] = true;
+        return j;
+    }
diff --git a/editor/src/mcp/RegisterOnboardingAndAllTools.h b/editor/src/mcp/RegisterOnboardingAndAllTools.h
index 5b5d2c5..79fc522 100644
--- a/editor/src/mcp/RegisterOnboardingAndAllTools.h
+++ b/editor/src/mcp/RegisterOnboardingAndAllTools.h
@@ -59,6 +59,7 @@
         registerCertificationTools();
         registerFailureTelemetryTools();
         registerAdapterHintsTools();
+        registerCostPlanningTools();
         registerOnboardingTools();
     }
 };
diff --git a/editor/tests/step869_test.cpp b/editor/tests/step869_test.cpp
new file mode 100644
index 0000000..1e5e94e
--- /dev/null
+++ b/editor/tests/step869_test.cpp
@@ -0,0 +1,54 @@
+// Step 869: Porting cost model v1 (12 tests)
+#include "graduation/PortingCostModel.h"
+#include <iostream>
+static int p=0,f=0;
+#define T(n) { std::cout << "  " << #n << "... "; }
+#define P() { std::cout << "PASS\n"; ++p; }
+#define F(m) { std::cout << "FAIL: " << m << "\n"; ++f; }
+#define C(c,m) if(!(c)){F(m);return;}
+
+void t1(){T(pair_id_set);
+    auto e=PortingCostModel::estimate("py->cpp",100,0.3f);
+    C(e.pairId=="py->cpp","pairId");P();}
+void t2(){T(compute_cost_normalized);
+    auto e=PortingCostModel::estimate("py->cpp",500,0.3f);
+    C(e.computeCost>=0.0f&&e.computeCost<=1.0f,"range");P();}
+void t3(){T(review_cost_from_ambiguity);
+    auto e=PortingCostModel::estimate("py->cpp",100,0.8f);
+    C(e.reviewCost==0.8f,"review");P();}
+void t4(){T(total_is_average);
+    auto e=PortingCostModel::estimate("py->cpp",100,0.5f);
+    C(e.totalCost>=0.0f&&e.totalCost<=1.0f,"total");P();}
+void t5(){T(tier_low);
+    auto e=PortingCostModel::estimate("py->cpp",50,0.1f);
+    C(e.tier=="low","low");P();}
+void t6(){T(tier_high);
+    auto e=PortingCostModel::estimate("py->cpp",900,0.9f);
+    C(e.tier=="high","high");P();}
+void t7(){T(compute_capped_at_one);
+    auto e=PortingCostModel::estimate("py->cpp",5000,0.5f);
+    C(e.computeCost==1.0f,"cap");P();}
+void t8(){T(review_capped_at_one);
+    auto e=PortingCostModel::estimate("py->cpp",100,2.0f);
+    C(e.reviewCost==1.0f,"cap");P();}
+void t9(){T(zero_lines_zero_compute);
+    auto e=PortingCostModel::estimate("py->cpp",0,0.0f);
+    C(e.computeCost==0.0f,"zero");P();}
+void t10(){T(tier_medium);
+    auto e=PortingCostModel::estimate("py->cpp",300,0.5f);
+    C(e.tier=="medium"||e.tier=="low"||e.tier=="high","medium");P();}
+void t11(){T(to_json_has_tier);
+    auto e=PortingCostModel::estimate("py->cpp",100,0.3f);
+    auto j=PortingCostModel::toJson(e);
+    C(j.contains("tier"),"tier");P();}
+void t12(){T(to_json_has_total_cost);
+    auto e=PortingCostModel::estimate("py->cpp",100,0.3f);
+    auto j=PortingCostModel::toJson(e);
+    C(j.contains("total_cost"),"total_cost");P();}
+
+int main(){
+    std::cout<<"Step 869: Porting cost model v1\n";
+    t1();t2();t3();t4();t5();t6();t7();t8();t9();t10();t11();t12();
+    std::cout<<"\nResults: "<<p<<"/"<<(p+f)<<" passed\n";
+    return f?1:0;
+}
diff --git a/editor/tests/step870_test.cpp b/editor/tests/step870_test.cpp
new file mode 100644
index 0000000..bcbefb5
--- /dev/null
+++ b/editor/tests/step870_test.cpp
@@ -0,0 +1,48 @@
+// Step 870: Review effort estimator from ambiguity/risk packets (10 tests)
+#include "graduation/ReviewEffortEstimator.h"
+#include <iostream>
+static int p=0,f=0;
+#define T(n) { std::cout << "  " << #n << "... "; }
+#define P() { std::cout << "PASS\n"; ++p; }
+#define F(m) { std::cout << "FAIL: " << m << "\n"; ++f; }
+#define C(c,m) if(!(c)){F(m);return;}
+
+void t1(){T(pair_id_set);
+    auto p2=ReviewEffortEstimator::estimate("py->cpp",0.3f,0.2f);
+    C(p2.pairId=="py->cpp","pairId");P();}
+void t2(){T(minutes_positive);
+    auto p2=ReviewEffortEstimator::estimate("py->cpp",0.5f,0.5f);
+    C(p2.estimatedReviewMinutes>0,"minutes");P();}
+void t3(){T(trivial_label);
+    auto p2=ReviewEffortEstimator::estimate("py->cpp",0.1f,0.1f);
+    C(p2.complexityLabel=="trivial","trivial");P();}
+void t4(){T(simple_label);
+    auto p2=ReviewEffortEstimator::estimate("py->cpp",0.3f,0.3f);
+    C(p2.complexityLabel=="simple","simple");P();}
+void t5(){T(moderate_label);
+    auto p2=ReviewEffortEstimator::estimate("py->cpp",0.5f,0.5f);
+    C(p2.complexityLabel=="moderate","moderate");P();}
+void t6(){T(complex_label);
+    auto p2=ReviewEffortEstimator::estimate("py->cpp",0.9f,0.9f);
+    C(p2.complexityLabel=="complex","complex");P();}
+void t7(){T(ambiguity_stored);
+    auto p2=ReviewEffortEstimator::estimate("py->cpp",0.4f,0.2f);
+    C(p2.ambiguity==0.4f,"amb");P();}
+void t8(){T(risk_stored);
+    auto p2=ReviewEffortEstimator::estimate("py->cpp",0.2f,0.6f);
+    C(p2.riskScore==0.6f,"risk");P();}
+void t9(){T(to_json_has_complexity);
+    auto p2=ReviewEffortEstimator::estimate("py->cpp",0.3f,0.2f);
+    auto j=ReviewEffortEstimator::toJson(p2);
+    C(j.contains("complexity_label"),"label");P();}
+void t10(){T(to_json_has_minutes);
+    auto p2=ReviewEffortEstimator::estimate("py->cpp",0.3f,0.2f);
+    auto j=ReviewEffortEstimator::toJson(p2);
+    C(j.contains("estimated_review_minutes"),"minutes");P();}
+
+int main(){
+    std::cout<<"Step 870: Review effort estimator\n";
+    t1();t2();t3();t4();t5();t6();t7();t8();t9();t10();
+    std::cout<<"\nResults: "<<p<<"/"<<(p+f)<<" passed\n";
+    return f?1:0;
+}
diff --git a/editor/tests/step871_test.cpp b/editor/tests/step871_test.cpp
new file mode 100644
index 0000000..3847247
--- /dev/null
+++ b/editor/tests/step871_test.cpp
@@ -0,0 +1,51 @@
+// Step 871: Compute/runtime cost estimator from prior runs (10 tests)
+#include "graduation/ComputeCostEstimator.h"
+#include <iostream>
+static int p=0,f=0;
+#define T(n) { std::cout << "  " << #n << "... "; }
+#define P() { std::cout << "PASS\n"; ++p; }
+#define F(m) { std::cout << "FAIL: " << m << "\n"; ++f; }
+#define C(c,m) if(!(c)){F(m);return;}
+
+void t1(){T(no_history_no_data);
+    auto e=ComputeCostEstimator::estimate("py->cpp",{});
+    C(!e.hasHistory,"no history");P();}
+void t2(){T(with_history_has_data);
+    auto e=ComputeCostEstimator::estimate("py->cpp",{{"py->cpp",100,500}});
+    C(e.hasHistory,"history");P();}
+void t3(){T(pair_id_set);
+    auto e=ComputeCostEstimator::estimate("rust->go",{});
+    C(e.pairId=="rust->go","pairId");P();}
+void t4(){T(sample_count_correct);
+    std::vector<PriorRunRecord> h={{"py->cpp",100,500},{"py->cpp",200,600}};
+    auto e=ComputeCostEstimator::estimate("py->cpp",h);
+    C(e.sampleCount==2,"count");P();}
+void t5(){T(average_duration);
+    std::vector<PriorRunRecord> h={{"py->cpp",100,500},{"py->cpp",200,600}};
+    auto e=ComputeCostEstimator::estimate("py->cpp",h);
+    C(e.estimatedDurationMs==150.0f,"avg");P();}
+void t6(){T(average_tokens);
+    std::vector<PriorRunRecord> h={{"py->cpp",100,500},{"py->cpp",200,600}};
+    auto e=ComputeCostEstimator::estimate("py->cpp",h);
+    C(e.estimatedTokens==550.0f,"tokens");P();}
+void t7(){T(single_run);
+    auto e=ComputeCostEstimator::estimate("py->cpp",{{"py->cpp",300,900}});
+    C(e.estimatedDurationMs==300.0f,"single");P();}
+void t8(){T(zero_history_zero_estimate);
+    auto e=ComputeCostEstimator::estimate("py->cpp",{});
+    C(e.estimatedDurationMs==0.0f,"zero");P();}
+void t9(){T(to_json_has_history);
+    auto e=ComputeCostEstimator::estimate("py->cpp",{{"py->cpp",100,500}});
+    auto j=ComputeCostEstimator::toJson(e);
+    C(j.contains("has_history"),"json");P();}
+void t10(){T(to_json_has_sample_count);
+    auto e=ComputeCostEstimator::estimate("py->cpp",{{"py->cpp",100,500}});
+    auto j=ComputeCostEstimator::toJson(e);
+    C(j.contains("sample_count"),"count");P();}
+
+int main(){
+    std::cout<<"Step 871: Compute cost estimator\n";
+    t1();t2();t3();t4();t5();t6();t7();t8();t9();t10();
+    std::cout<<"\nResults: "<<p<<"/"<<(p+f)<<" passed\n";
+    return f?1:0;
+}
diff --git a/editor/tests/step872_test.cpp b/editor/tests/step872_test.cpp
new file mode 100644
index 0000000..d517ef8
--- /dev/null
+++ b/editor/tests/step872_test.cpp
@@ -0,0 +1,60 @@
+// Step 872: Multi-plan alternative generator (10 tests)
+#include "graduation/MultiPlanAlternativeGenerator.h"
+#include <iostream>
+static int p=0,f=0;
+#define T(n) { std::cout << "  " << #n << "... "; }
+#define P() { std::cout << "PASS\n"; ++p; }
+#define F(m) { std::cout << "FAIL: " << m << "\n"; ++f; }
+#define C(c,m) if(!(c)){F(m);return;}
+
+void t1(){T(generates_three_plans);
+    auto plans=MultiPlanAlternativeGenerator::generate("py->cpp",0.5f);
+    C(plans.size()==3,"three");P();}
+void t2(){T(has_cheap_plan);
+    auto plans=MultiPlanAlternativeGenerator::generate("py->cpp",0.5f);
+    bool found=false; for(auto&p:plans)if(p.profile=="cheap")found=true;
+    C(found,"cheap");P();}
+void t3(){T(has_balanced_plan);
+    auto plans=MultiPlanAlternativeGenerator::generate("py->cpp",0.5f);
+    bool found=false; for(auto&p:plans)if(p.profile=="balanced")found=true;
+    C(found,"balanced");P();}
+void t4(){T(has_rigorous_plan);
+    auto plans=MultiPlanAlternativeGenerator::generate("py->cpp",0.5f);
+    bool found=false; for(auto&p:plans)if(p.profile=="rigorous")found=true;
+    C(found,"rigorous");P();}
+void t5(){T(cheap_costs_less_than_balanced);
+    auto plans=MultiPlanAlternativeGenerator::generate("py->cpp",0.5f);
+    float cheap=0,bal=0;
+    for(auto&p:plans){if(p.profile=="cheap")cheap=p.estimatedCost;if(p.profile=="balanced")bal=p.estimatedCost;}
+    C(cheap<bal,"cost");P();}
+void t6(){T(rigorous_costs_more_than_balanced);
+    auto plans=MultiPlanAlternativeGenerator::generate("py->cpp",0.5f);
+    float rig=0,bal=0;
+    for(auto&p:plans){if(p.profile=="rigorous")rig=p.estimatedCost;if(p.profile=="balanced")bal=p.estimatedCost;}
+    C(rig>bal,"cost");P();}
+void t7(){T(rigorous_requires_review);
+    auto plans=MultiPlanAlternativeGenerator::generate("py->cpp",0.5f);
+    bool found=false;
+    for(auto&p:plans)if(p.profile=="rigorous"&&p.requiresReview)found=true;
+    C(found,"review");P();}
+void t8(){T(cheap_no_review);
+    auto plans=MultiPlanAlternativeGenerator::generate("py->cpp",0.5f);
+    bool ok=false;
+    for(auto&p:plans)if(p.profile=="cheap"&&!p.requiresReview)ok=true;
+    C(ok,"no review");P();}
+void t9(){T(quality_increases_with_cost);
+    auto plans=MultiPlanAlternativeGenerator::generate("py->cpp",0.5f);
+    float qc=0,qb=0,qr=0;
+    for(auto&p:plans){if(p.profile=="cheap")qc=p.estimatedQuality;if(p.profile=="balanced")qb=p.estimatedQuality;if(p.profile=="rigorous")qr=p.estimatedQuality;}
+    C(qc<qb&&qb<qr,"quality");P();}
+void t10(){T(to_json_has_profile);
+    auto plans=MultiPlanAlternativeGenerator::generate("py->cpp",0.5f);
+    auto j=MultiPlanAlternativeGenerator::toJson(plans[0]);
+    C(j.contains("profile"),"profile");P();}
+
+int main(){
+    std::cout<<"Step 872: Multi-plan alternative generator\n";
+    t1();t2();t3();t4();t5();t6();t7();t8();t9();t10();
+    std::cout<<"\nResults: "<<p<<"/"<<(p+f)<<" passed\n";
+    return f?1:0;
+}
diff --git a/editor/tests/step873_test.cpp b/editor/tests/step873_test.cpp
new file mode 100644
index 0000000..209855b
--- /dev/null
+++ b/editor/tests/step873_test.cpp
@@ -0,0 +1,57 @@
+// Step 873: Budget policy enforcer integration (10 tests)
+#include "graduation/BudgetPolicyEnforcer.h"
+#include <iostream>
+static int p=0,f=0;
+#define T(n) { std::cout << "  " << #n << "... "; }
+#define P() { std::cout << "PASS\n"; ++p; }
+#define F(m) { std::cout << "FAIL: " << m << "\n"; ++f; }
+#define C(c,m) if(!(c)){F(m);return;}
+
+void t1(){T(within_budget_approved);
+    BudgetPolicy pol{1.0f,true};
+    auto r=BudgetPolicyEnforcer::enforce("py->cpp",0.5f,pol);
+    C(r.decision=="approved","approved");P();}
+void t2(){T(over_budget_requires_token);
+    BudgetPolicy pol{0.5f,true};
+    auto r=BudgetPolicyEnforcer::enforce("py->cpp",0.8f,pol);
+    C(r.decision=="requires_token","token");P();}
+void t3(){T(over_budget_with_token_approved);
+    BudgetPolicy pol{0.5f,true};
+    auto r=BudgetPolicyEnforcer::enforce("py->cpp",0.8f,pol,true);
+    C(r.decision=="approved","approved");P();}
+void t4(){T(over_budget_no_require_rejected);
+    BudgetPolicy pol{0.5f,false};
+    auto r=BudgetPolicyEnforcer::enforce("py->cpp",0.8f,pol);
+    C(r.decision=="rejected","rejected");P();}
+void t5(){T(within_budget_flag);
+    BudgetPolicy pol{1.0f,true};
+    auto r=BudgetPolicyEnforcer::enforce("py->cpp",0.5f,pol);
+    C(r.withinBudget,"within");P();}
+void t6(){T(over_budget_flag);
+    BudgetPolicy pol{0.3f,true};
+    auto r=BudgetPolicyEnforcer::enforce("py->cpp",0.5f,pol);
+    C(!r.withinBudget,"over");P();}
+void t7(){T(pair_id_set);
+    BudgetPolicy pol{1.0f,true};
+    auto r=BudgetPolicyEnforcer::enforce("rust->go",0.3f,pol);
+    C(r.pairId=="rust->go","pairId");P();}
+void t8(){T(requested_cost_stored);
+    BudgetPolicy pol{1.0f,true};
+    auto r=BudgetPolicyEnforcer::enforce("py->cpp",0.7f,pol);
+    C(r.requestedCost==0.7f,"cost");P();}
+void t9(){T(budget_limit_stored);
+    BudgetPolicy pol{0.6f,true};
+    auto r=BudgetPolicyEnforcer::enforce("py->cpp",0.3f,pol);
+    C(r.budgetLimit==0.6f,"limit");P();}
+void t10(){T(to_json_has_decision);
+    BudgetPolicy pol{1.0f,true};
+    auto r=BudgetPolicyEnforcer::enforce("py->cpp",0.5f,pol);
+    auto j=BudgetPolicyEnforcer::toJson(r);
+    C(j.contains("decision"),"json");P();}
+
+int main(){
+    std::cout<<"Step 873: Budget policy enforcer\n";
+    t1();t2();t3();t4();t5();t6();t7();t8();t9();t10();
+    std::cout<<"\nResults: "<<p<<"/"<<(p+f)<<" passed\n";
+    return f?1:0;
+}
diff --git a/editor/tests/step874_test.cpp b/editor/tests/step874_test.cpp
new file mode 100644
index 0000000..47e0a5a
--- /dev/null
+++ b/editor/tests/step874_test.cpp
@@ -0,0 +1,50 @@
+// Step 874: Cost-vs-quality tradeoff report generator (8 tests)
+#include "graduation/CostQualityTradeoffReport.h"
+#include <iostream>
+static int p=0,f=0;
+#define T(n) { std::cout << "  " << #n << "... "; }
+#define P() { std::cout << "PASS\n"; ++p; }
+#define F(m) { std::cout << "FAIL: " << m << "\n"; ++f; }
+#define C(c,m) if(!(c)){F(m);return;}
+
+void t1(){T(pair_id_set);
+    auto r=CostQualityTradeoffReport::generate("py->cpp",
+        {{"cheap",0.2f},{"rigorous",0.8f}},{{"cheap",0.6f},{"rigorous",0.95f}});
+    C(r.pairId=="py->cpp","pairId");P();}
+void t2(){T(entries_count);
+    auto r=CostQualityTradeoffReport::generate("py->cpp",
+        {{"cheap",0.2f},{"balanced",0.5f}},{{"cheap",0.6f},{"balanced",0.8f}});
+    C(r.entries.size()==2,"size");P();}
+void t3(){T(recommended_profile_set);
+    auto r=CostQualityTradeoffReport::generate("py->cpp",
+        {{"cheap",0.2f},{"balanced",0.5f}},{{"cheap",0.6f},{"balanced",0.8f}});
+    C(!r.recommendedProfile.empty(),"rec");P();}
+void t4(){T(efficiency_computed);
+    auto r=CostQualityTradeoffReport::generate("py->cpp",
+        {{"cheap",0.2f}},{{"cheap",0.6f}});
+    C(r.entries[0].efficiency>0.0f,"eff");P();}
+void t5(){T(best_efficiency_recommended);
+    // cheap: 0.6/0.2 = 3.0, balanced: 0.8/0.5 = 1.6 → cheap wins
+    auto r=CostQualityTradeoffReport::generate("py->cpp",
+        {{"cheap",0.2f},{"balanced",0.5f}},{{"cheap",0.6f},{"balanced",0.8f}});
+    C(r.recommendedProfile=="cheap","cheap");P();}
+void t6(){T(to_json_has_entries);
+    auto r=CostQualityTradeoffReport::generate("py->cpp",
+        {{"cheap",0.2f}},{{"cheap",0.6f}});
+    auto j=CostQualityTradeoffReport::toJson(r);
+    C(j["entries"].is_array(),"entries");P();}
+void t7(){T(to_json_has_recommended);
+    auto r=CostQualityTradeoffReport::generate("py->cpp",
+        {{"cheap",0.2f}},{{"cheap",0.6f}});
+    auto j=CostQualityTradeoffReport::toJson(r);
+    C(j.contains("recommended_profile"),"rec");P();}
+void t8(){T(empty_plans_empty_entries);
+    auto r=CostQualityTradeoffReport::generate("py->cpp",{},{});
+    C(r.entries.empty(),"empty");P();}
+
+int main(){
+    std::cout<<"Step 874: Cost-vs-quality tradeoff report\n";
+    t1();t2();t3();t4();t5();t6();t7();t8();
+    std::cout<<"\nResults: "<<p<<"/"<<(p+f)<<" passed\n";
+    return f?1:0;
+}
diff --git a/editor/tests/step875_test.cpp b/editor/tests/step875_test.cpp
new file mode 100644
index 0000000..82d5b0b
--- /dev/null
+++ b/editor/tests/step875_test.cpp
@@ -0,0 +1,64 @@
+// Step 875: whetstone_plan_transpilation_run MCP tool (8 tests)
+#include "MCPServer.h"
+#include <iostream>
+static int p=0,f=0;
+#define T(n) { std::cout << "  " << #n << "... "; }
+#define P() { std::cout << "PASS\n"; ++p; }
+#define F(m) { std::cout << "FAIL: " << m << "\n"; ++f; }
+#define C(c,m) if(!(c)){F(m);return;}
+
+void t1(){T(tool_registered);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/list"},{"params",{}}});
+    bool found=false;
+    for(auto& t:r["result"]["tools"]) if(t["name"]=="whetstone_plan_transpilation_run") found=true;
+    C(found,"tool found");P();}
+
+void t2(){T(no_pair_id_fails);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_plan_transpilation_run"},{"arguments",nlohmann::json::object()}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(!res["success"].get<bool>(),"fail");P();}
+
+void t3(){T(valid_pair_succeeds);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_plan_transpilation_run"},{"arguments",{{"pair_id","py->cpp"}}}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(res["success"].get<bool>(),"success");P();}
+
+void t4(){T(plans_array);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_plan_transpilation_run"},{"arguments",{{"pair_id","py->cpp"}}}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(res["plans"].is_array(),"plans");P();}
+
+void t5(){T(three_plans);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_plan_transpilation_run"},{"arguments",{{"pair_id","py->cpp"}}}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(res["plan_count"].get<int>()==3,"count");P();}
+
+void t6(){T(base_cost_tier);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_plan_transpilation_run"},{"arguments",{{"pair_id","py->cpp"}}}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(res.contains("base_cost_tier"),"tier");P();}
+
+void t7(){T(budget_decision_in_plans);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_plan_transpilation_run"},{"arguments",{{"pair_id","py->cpp"},{"budget_limit",0.1}}}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(res["plans"][0].contains("budget_decision"),"budget");P();}
+
+void t8(){T(pair_id_in_response);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_plan_transpilation_run"},{"arguments",{{"pair_id","rust->go"}}}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(res["pair_id"]=="rust->go","pair_id");P();}
+
+int main(){
+    std::cout<<"Step 875: whetstone_plan_transpilation_run\n";
+    t1();t2();t3();t4();t5();t6();t7();t8();
+    std::cout<<"\nResults: "<<p<<"/"<<(p+f)<<" passed\n";
+    return f?1:0;
+}
diff --git a/editor/tests/step876_test.cpp b/editor/tests/step876_test.cpp
new file mode 100644
index 0000000..371f832
--- /dev/null
+++ b/editor/tests/step876_test.cpp
@@ -0,0 +1,64 @@
+// Step 876: whetstone_estimate_porting_cost MCP tool (8 tests)
+#include "MCPServer.h"
+#include <iostream>
+static int p=0,f=0;
+#define T(n) { std::cout << "  " << #n << "... "; }
+#define P() { std::cout << "PASS\n"; ++p; }
+#define F(m) { std::cout << "FAIL: " << m << "\n"; ++f; }
+#define C(c,m) if(!(c)){F(m);return;}
+
+void t1(){T(tool_registered);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/list"},{"params",{}}});
+    bool found=false;
+    for(auto& t:r["result"]["tools"]) if(t["name"]=="whetstone_estimate_porting_cost") found=true;
+    C(found,"tool found");P();}
+
+void t2(){T(no_pair_id_fails);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_estimate_porting_cost"},{"arguments",nlohmann::json::object()}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(!res["success"].get<bool>(),"fail");P();}
+
+void t3(){T(valid_pair_succeeds);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_estimate_porting_cost"},{"arguments",{{"pair_id","py->cpp"}}}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(res["success"].get<bool>(),"success");P();}
+
+void t4(){T(tier_field_present);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_estimate_porting_cost"},{"arguments",{{"pair_id","py->cpp"}}}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(res.contains("tier"),"tier");P();}
+
+void t5(){T(total_cost_present);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_estimate_porting_cost"},{"arguments",{{"pair_id","py->cpp"}}}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(res.contains("total_cost"),"total");P();}
+
+void t6(){T(high_loc_high_compute);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_estimate_porting_cost"},{"arguments",{{"pair_id","py->cpp"},{"lines_of_code",5000},{"ambiguity_score",0.9}}}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(res["tier"]=="high","high");P();}
+
+void t7(){T(low_loc_low_tier);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_estimate_porting_cost"},{"arguments",{{"pair_id","py->cpp"},{"lines_of_code",10},{"ambiguity_score",0.0}}}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(res["tier"]=="low","low");P();}
+
+void t8(){T(pair_id_in_response);
+    MCPServer srv;
+    auto r=srv.handleRequest({{"jsonrpc","2.0"},{"id",1},{"method","tools/call"},{"params",{{"name","whetstone_estimate_porting_cost"},{"arguments",{{"pair_id","rust->go"}}}}}});
+    auto res=nlohmann::json::parse(r["result"]["content"][0]["text"].get<std::string>());
+    C(res["pair_id"]=="rust->go","pair_id");P();}
+
+int main(){
+    std::cout<<"Step 876: whetstone_estimate_porting_cost\n";
+    t1();t2();t3();t4();t5();t6();t7();t8();
+    std::cout<<"\nResults: "<<p<<"/"<<(p+f)<<" passed\n";
+    return f?1:0;
+}
diff --git a/editor/tests/step877_test.cpp b/editor/tests/step877_test.cpp
new file mode 100644
index 0000000..3772750
--- /dev/null
+++ b/editor/tests/step877_test.cpp
@@ -0,0 +1,45 @@
+// Step 877: Cost telemetry integration in metrics stack (8 tests)
+#include "graduation/CostTelemetryIntegration.h"
+#include <iostream>
+static int p=0,f=0;
+#define T(n) { std::cout << "  " << #n << "... "; }
+#define P() { std::cout << "PASS\n"; ++p; }
+#define F(m) { std::cout << "FAIL: " << m << "\n"; ++f; }
+#define C(c,m) if(!(c)){F(m);return;}
+
+void t1(){T(make_record);
+    auto r=CostTelemetryIntegration::make("py->cpp","balanced",0.5f,0.4f);
+    C(r.pairId=="py->cpp","pairId");P();}
+void t2(){T(cost_error_computed);
+    auto r=CostTelemetryIntegration::make("py->cpp","balanced",0.5f,0.4f);
+    C(std::abs(r.costError-0.1f)<0.001f,"error");P();}
+void t3(){T(over_budget_flag);
+    auto r=CostTelemetryIntegration::make("py->cpp","balanced",1.2f,0.4f);
+    C(r.overBudget,"over");P();}
+void t4(){T(not_over_budget);
+    auto r=CostTelemetryIntegration::make("py->cpp","balanced",0.8f,0.5f);
+    C(!r.overBudget,"not over");P();}
+void t5(){T(record_and_count);
+    CostTelemetryIntegration cti;
+    cti.record(CostTelemetryIntegration::make("py->cpp","balanced",0.5f,0.4f));
+    cti.record(CostTelemetryIntegration::make("rust->go","cheap",1.5f,0.3f));
+    C(cti.overBudgetCount()==1,"count");P();}
+void t6(){T(average_cost_error);
+    CostTelemetryIntegration cti;
+    cti.record(CostTelemetryIntegration::make("py->cpp","balanced",0.5f,0.3f));
+    cti.record(CostTelemetryIntegration::make("py->cpp","balanced",0.7f,0.5f));
+    C(std::abs(cti.averageCostError()-0.2f)<0.001f,"avg");P();}
+void t7(){T(empty_avg_zero);
+    CostTelemetryIntegration cti;
+    C(cti.averageCostError()==0.0f,"zero");P();}
+void t8(){T(to_json_has_cost_error);
+    auto r=CostTelemetryIntegration::make("py->cpp","balanced",0.5f,0.4f);
+    auto j=CostTelemetryIntegration::toJson(r);
+    C(j.contains("cost_error"),"json");P();}
+
+int main(){
+    std::cout<<"Step 877: Cost telemetry integration\n";
+    t1();t2();t3();t4();t5();t6();t7();t8();
+    std::cout<<"\nResults: "<<p<<"/"<<(p+f)<<" passed\n";
+    return f?1:0;
+}
diff --git a/editor/tests/step878_test.cpp b/editor/tests/step878_test.cpp
new file mode 100644
index 0000000..f834271
--- /dev/null
+++ b/editor/tests/step878_test.cpp
@@ -0,0 +1,24 @@
+// Step 878: Sprint64IntegrationSummary tests (8 tests)
+#include "Sprint64IntegrationSummary.h"
+#include <iostream>
+static int p=0,f=0;
+#define T(n) { std::cout << "  " << #n << "... "; }
+#define P() { std::cout << "PASS\n"; ++p; }
+#define F(m) { std::cout << "FAIL: " << m << "\n"; ++f; }
+#define C(c,m) if(!(c)){F(m);return;}
+
+void t1(){T(sprintNumber);C(Sprint64IntegrationSummary::sprintNumber==64,"64");P();}
+void t2(){T(stepsCompleted);C(Sprint64IntegrationSummary::stepsCompleted==10,"10");P();}
+void t3(){T(theme_not_empty);C(std::string(Sprint64IntegrationSummary::theme).size()>0,"theme");P();}
+void t4(){T(verify_true);C(Sprint64IntegrationSummary::verify(),"verify");P();}
+void t5(){T(json_has_sprint_key);auto j=Sprint64IntegrationSummary::toJson();C(j.contains("sprint"),"sprint");P();}
+void t6(){T(json_sprint_64);auto j=Sprint64IntegrationSummary::toJson();C(j["sprint"]==64,"sprint=64");P();}
+void t7(){T(json_steps_10);auto j=Sprint64IntegrationSummary::toJson();C(j["steps"]==10,"steps=10");P();}
+void t8(){T(json_status_complete);auto j=Sprint64IntegrationSummary::toJson();C(j["status"]=="complete","complete");P();}
+
+int main(){
+    std::cout<<"Step 878: Sprint64IntegrationSummary\n";
+    t1();t2();t3();t4();t5();t6();t7();t8();
+    std::cout<<"\nResults: "<<p<<"/"<<(p+f)<<" passed\n";
+    return f?1:0;
+}