diff --git a/packages/runtime/src/app/RuntimeApp.ts b/packages/runtime/src/app/RuntimeApp.ts
index d1e350a..7d3b0f5 100755
--- a/packages/runtime/src/app/RuntimeApp.ts
+++ b/packages/runtime/src/app/RuntimeApp.ts
@@ -273,7 +273,7 @@ export class RuntimeApp {
 
       // Register tools through the CppToolRegistrar
       // This follows INV-4: registered via capability boundary
-      registrar.register(this.tool_registry, this.config.project_root)
+      registrar.register(this.tool_registry, this.config.project_root, this.event_ingestor)
       this.logger.info('cpp toolchain registered', { capability_id: 'aircoding-cpp-toolchain' })
     } catch (e: any) {
       this.logger.warn('cpp toolchain registration failed', { error: e.message })
diff --git a/packages/toolchain-cpp/src/CppToolRegistrar.ts b/packages/toolchain-cpp/src/CppToolRegistrar.ts
index bbce474..c59ceb8 100755
--- a/packages/toolchain-cpp/src/CppToolRegistrar.ts
+++ b/packages/toolchain-cpp/src/CppToolRegistrar.ts
@@ -5,6 +5,9 @@
  * @module packages/toolchain-cpp/src/CppToolRegistrar
  */
 
+import { writeFileSync, mkdirSync, existsSync } from 'fs'
+import { join, dirname } from 'path'
+import { randomUUID } from 'crypto'
 import { CPP_TOOLCHAIN_CAPABILITY } from './capability.js'
 import { CppProjectDetector } from './detect/CppProjectDetector.js'
 import { CMakeConfigurator } from './build/CMakeConfigurator.js'
@@ -13,14 +16,37 @@ import { CppTestRunner } from './test/CppTestRunner.js'
 import { CppcheckRunner } from './analysis/CppcheckRunner.js'
 import { ClangdClient } from './analysis/ClangdClient.js'
 
+// Duck-typed EventSink — avoids direct runtime import (INV-4)
+export interface EventSink {
+  ingest(event: any): Promise<void>
+}
+
+// Context passed through from RuntimeApp
+export interface CppContext {
+  session_id: string
+  project_id: string
+  project_root: string
+  task_id?: string
+  agent_id?: string
+  agent_type?: string
+  tool_run_id?: string
+}
+
+interface ArtifactInfo {
+  artifact_id: string
+  path: string
+  size_bytes: number
+  sha256_calc: string
+}
+
 export class CppToolRegistrar {
   manifest = CPP_TOOLCHAIN_CAPABILITY
 
-  /**
-   * Register all cpp.* tools with the provided registry.
-   * INV-4: This is called through CapabilityRegistry boundary, never via direct runtime import.
-   */
-  register(registry: { register(name: string, definition: any, executor: (call: any) => Promise<any>): void }, project_root: string): void {
+  register(
+    registry: { register(name: string, definition: any, executor: (call: any, ctx?: any) => Promise<any>): void },
+    project_root: string,
+    event_sink?: EventSink,
+  ): void {
     const detector = new CppProjectDetector(project_root)
     const configurator = new CMakeConfigurator()
     const builder = new CppBuilder()
@@ -28,90 +54,269 @@ export class CppToolRegistrar {
     const cppcheck = new CppcheckRunner()
     const clangd = new ClangdClient()
 
+    // cpp.detect — no external command, no evidence needed
     // cpp.detect
     registry.register('cpp.detect', {
       name: 'cpp.detect', category: 'toolchain',
       description: 'Detect C++ project structure and toolchain',
       input_schema: CPP_TOOLCHAIN_CAPABILITY.tools[0].input_schema,
       permissions: { read: true, write: false, network: false }, streaming: false
-    }, async (call) => {
+    }, async (call, tool_ctx) => {
       const result = detector.detect()
       return { status: 'ok', call_id: call.call_id, tool_name: 'cpp.detect', output: result, metadata: { timestamp: new Date().toISOString() } }
     })
 
-    // cpp.configure
+    // cpp.configure — cmake configure, evidence on failure
     registry.register('cpp.configure', {
       name: 'cpp.configure', category: 'toolchain',
       description: 'Configure C++ build with CMake',
       input_schema: CPP_TOOLCHAIN_CAPABILITY.tools[1].input_schema,
       permissions: { read: true, write: true, network: false }, streaming: false
-    }, async (call) => {
+    }, async (call, tool_ctx) => {
+      const ctx: CppContext = tool_ctx || {}
+      const cmd_id = this.cmd_id()
+      await this.emit(event_sink, ctx, this.command_started(cmd_id, ctx, 'cmake configure'))
+
       const result = configurator.configure({ project_root, generator: call.arguments?.generator as any, build_type: call.arguments?.build_type as any })
+      const duration_ms = Date.now() - Date.parse(new Date().toISOString()) + 1
+
       if (result.ok) {
-        return { status: 'ok', call_id: call.call_id, tool_name: 'cpp.configure', output: result, metadata: { timestamp: new Date().toISOString() } }
+        await this.emit(event_sink, ctx, this.command_completed(cmd_id, ctx, 0, duration_ms))
+        return { status: 'ok', call_id: call.call_id, tool_name: 'cpp.configure', output: result, metadata: { timestamp: new Date().toISOString(), command_run_id: cmd_id } }
       } else {
-        return { status: 'error', call_id: call.call_id, tool_name: 'cpp.configure', error: { error_id: call.call_id, kind: 'tool_error', severity: 'error', message: result.error || 'configure failed', retryability: 'not_retryable', semantic_signature: 'cpp.configure' }, metadata: { timestamp: new Date().toISOString() } }
+        const { stdout_id, stderr_id } = await this.write_artifacts(event_sink, ctx, project_root, cmd_id, '', result.error || 'configure failed')
+        const diag_ids = await this.emit_diagnostics(event_sink, ctx, cmd_id, [{ file: 'CMakeLists.txt', line: 0, column: 0, severity: 'error', message: result.error || 'configure failed', semantic_signature: 'cmake.configure' }])
+        await this.emit(event_sink, ctx, this.command_failed(cmd_id, ctx, 1, duration_ms, stdout_id, stderr_id, diag_ids))
+        await this.emit_evidence(event_sink, ctx, cmd_id, 'other', { error: result.error })
+        return { status: 'error', call_id: call.call_id, tool_name: 'cpp.configure', error: { error_id: call.call_id, kind: 'tool_error', severity: 'error', message: result.error || 'configure failed', retryability: 'not_retryable', semantic_signature: 'cpp.configure' }, metadata: { timestamp: new Date().toISOString(), command_run_id: cmd_id, diagnostic_ids: diag_ids } }
       }
     })
 
-    // cpp.build
+    // cpp.build — cmake build, diagnostics + evidence
     registry.register('cpp.build', {
       name: 'cpp.build', category: 'toolchain',
       description: 'Build C++ project',
       input_schema: CPP_TOOLCHAIN_CAPABILITY.tools[2].input_schema,
       permissions: { read: true, write: true, network: false }, streaming: false
-    }, async (call) => {
+    }, async (call, tool_ctx) => {
+      const ctx: CppContext = tool_ctx || {}
+      const cmd_id = this.cmd_id()
+      await this.emit(event_sink, ctx, this.command_started(cmd_id, ctx, 'cmake --build'))
+
+      const build_start = Date.now()
       const result = builder.build(project_root + '/build', call.arguments?.target as string)
+      const duration_ms = Date.now() - build_start
+
       if (result.ok) {
-        return { status: 'ok', call_id: call.call_id, tool_name: 'cpp.build', output: { built: true, output: result.output, diagnostics: result.diagnostics, elapsed_ms: result.elapsed_ms }, metadata: { timestamp: new Date().toISOString() } }
+        await this.emit(event_sink, ctx, this.command_completed(cmd_id, ctx, 0, duration_ms))
+        return { status: 'ok', call_id: call.call_id, tool_name: 'cpp.build', output: { built: true, output: result.output, diagnostics: result.diagnostics, elapsed_ms: result.elapsed_ms }, metadata: { timestamp: new Date().toISOString(), command_run_id: cmd_id } }
       } else {
-        return { status: 'error', call_id: call.call_id, tool_name: 'cpp.build', error: { error_id: call.call_id, kind: 'tool_error', severity: 'error', message: result.output || 'build failed', retryability: 'not_retryable', semantic_signature: 'cpp.build' }, metadata: { timestamp: new Date().toISOString() } }
+        const { stdout_id, stderr_id } = await this.write_artifacts(event_sink, ctx, project_root, cmd_id, result.output, result.output)
+        const diag_ids = await this.emit_diagnostics(event_sink, ctx, cmd_id, result.diagnostics.map(d => ({ file: d.file || '', line: d.line || 0, column: d.column || 0, severity: d.severity || 'error', message: d.message, semantic_signature: d.semantic_signature || `build.${d.file}.${d.line}` })))
+        await this.emit(event_sink, ctx, this.command_failed(cmd_id, ctx, 1, duration_ms, stdout_id, stderr_id, diag_ids))
+        await this.emit_evidence(event_sink, ctx, cmd_id, 'build_output', { diagnostics: result.diagnostics.length })
+        return { status: 'error', call_id: call.call_id, tool_name: 'cpp.build', error: { error_id: call.call_id, kind: 'tool_error', severity: 'error', message: result.output || 'build failed', retryability: 'not_retryable', semantic_signature: 'cpp.build' }, metadata: { timestamp: new Date().toISOString(), command_run_id: cmd_id, diagnostic_ids: diag_ids } }
       }
     })
 
-    // cpp.test
+    // cpp.test — ctest, evidence on failure
     registry.register('cpp.test', {
       name: 'cpp.test', category: 'toolchain',
       description: 'Run C++ tests',
       input_schema: CPP_TOOLCHAIN_CAPABILITY.tools[3].input_schema,
       permissions: { read: true, write: false, network: false }, streaming: false
-    }, async (call) => {
+    }, async (call, tool_ctx) => {
+      const ctx: CppContext = tool_ctx || {}
+      const cmd_id = this.cmd_id()
+      await this.emit(event_sink, ctx, this.command_started(cmd_id, ctx, 'ctest'))
+
+      const test_start = Date.now()
       const result = tester.run_tests(project_root + '/build')
+      const duration_ms = Date.now() - test_start
+
       if (result.ok) {
-        return { status: 'ok', call_id: call.call_id, tool_name: 'cpp.test', output: result, metadata: { timestamp: new Date().toISOString() } }
+        await this.emit(event_sink, ctx, this.command_completed(cmd_id, ctx, 0, duration_ms))
+        return { status: 'ok', call_id: call.call_id, tool_name: 'cpp.test', output: result, metadata: { timestamp: new Date().toISOString(), command_run_id: cmd_id } }
       } else {
-        return { status: 'error', call_id: call.call_id, tool_name: 'cpp.test', error: { error_id: call.call_id, kind: 'tool_error', severity: 'error', message: result.output || 'test failed', retryability: 'not_retryable', semantic_signature: 'cpp.test' }, metadata: { timestamp: new Date().toISOString() } }
+        const { stdout_id, stderr_id } = await this.write_artifacts(event_sink, ctx, project_root, cmd_id, result.output, result.output)
+        await this.emit(event_sink, ctx, this.command_failed(cmd_id, ctx, 1, duration_ms, stdout_id, stderr_id, []))
+        await this.emit_evidence(event_sink, ctx, cmd_id, 'test_output', { passed: result.passed, failed: result.failed })
+        return { status: 'error', call_id: call.call_id, tool_name: 'cpp.test', error: { error_id: call.call_id, kind: 'tool_error', severity: 'error', message: result.output || 'test failed', retryability: 'not_retryable', semantic_signature: 'cpp.test' }, metadata: { timestamp: new Date().toISOString(), command_run_id: cmd_id } }
       }
     })
 
-    // cpp.cppcheck
+    // cpp.cppcheck — static analysis, diagnostics + evidence
     registry.register('cpp.cppcheck', {
       name: 'cpp.cppcheck', category: 'toolchain',
       description: 'Run cppcheck static analysis',
       input_schema: CPP_TOOLCHAIN_CAPABILITY.tools[4].input_schema,
       permissions: { read: true, write: false, network: false }, streaming: false
-    }, async (call) => {
+    }, async (call, tool_ctx) => {
+      const ctx: CppContext = tool_ctx || {}
+      const cmd_id = this.cmd_id()
+      await this.emit(event_sink, ctx, this.command_started(cmd_id, ctx, 'cppcheck'))
+
+      const check_start = Date.now()
       const result = cppcheck.run(project_root, { enable_all: call.arguments?.enable_all as boolean, check_config: call.arguments?.check_config as boolean })
+      const duration_ms = Date.now() - check_start
+
+      const diag_ids = await this.emit_diagnostics(event_sink, ctx, cmd_id, result.diagnostics.map(d => ({ file: d.file || '', line: d.line || 0, column: d.column || 0, severity: d.severity || 'warning', message: d.message, semantic_signature: d.semantic_signature || `cppcheck.${d.file}.${d.line}` })))
+
       if (result.ok) {
-        return { status: 'ok', call_id: call.call_id, tool_name: 'cpp.cppcheck', output: result, metadata: { timestamp: new Date().toISOString() } }
+        await this.emit(event_sink, ctx, this.command_completed(cmd_id, ctx, 0, duration_ms))
+        return { status: 'ok', call_id: call.call_id, tool_name: 'cpp.cppcheck', output: { ...result, diagnostic_ids: diag_ids }, metadata: { timestamp: new Date().toISOString(), command_run_id: cmd_id } }
       } else {
-        return { status: 'error', call_id: call.call_id, tool_name: 'cpp.cppcheck', error: { error_id: call.call_id, kind: 'tool_error', severity: 'error', message: result.output || 'cppcheck failed', retryability: 'not_retryable', semantic_signature: 'cpp.cppcheck' }, metadata: { timestamp: new Date().toISOString() } }
+        const { stdout_id, stderr_id } = await this.write_artifacts(event_sink, ctx, project_root, cmd_id, result.output, result.output)
+        await this.emit(event_sink, ctx, this.command_failed(cmd_id, ctx, 1, duration_ms, stdout_id, stderr_id, diag_ids))
+        await this.emit_evidence(event_sink, ctx, cmd_id, 'other', { diagnostics: result.diagnostics.length })
+        return { status: 'error', call_id: call.call_id, tool_name: 'cpp.cppcheck', error: { error_id: call.call_id, kind: 'tool_error', severity: 'error', message: result.output || 'cppcheck failed', retryability: 'not_retryable', semantic_signature: 'cpp.cppcheck' }, metadata: { timestamp: new Date().toISOString(), command_run_id: cmd_id, diagnostic_ids: diag_ids } }
       }
     })
 
-    // cpp.clangd
+    // cpp.clangd — LSP query, diagnostics
     registry.register('cpp.clangd', {
       name: 'cpp.clangd', category: 'toolchain',
       description: 'Query clangd for symbol info',
       input_schema: CPP_TOOLCHAIN_CAPABILITY.tools[5].input_schema,
       permissions: { read: true, write: false, network: false }, streaming: false
-    }, async (call) => {
+    }, async (call, tool_ctx) => {
+      const ctx: CppContext = tool_ctx || {}
+      const cmd_id = this.cmd_id()
+      await this.emit(event_sink, ctx, this.command_started(cmd_id, ctx, 'clangd --check'))
+
+      const clangd_start = Date.now()
       const result = await clangd.query_symbol(call.arguments?.file as string, call.arguments?.line as number, call.arguments?.column as number)
+      const duration_ms = Date.now() - clangd_start
+
       if (result.ok) {
-        return { status: 'ok', call_id: call.call_id, tool_name: 'cpp.clangd', output: result, metadata: { timestamp: new Date().toISOString() } }
+        const diag_ids = await this.emit_diagnostics(event_sink, ctx, cmd_id, (result.diagnostics || []).map(d => ({ file: d.file, line: d.line, column: 0, severity: d.severity, message: d.message, semantic_signature: `clangd.${d.file}.${d.line}` })))
+        await this.emit(event_sink, ctx, this.command_completed(cmd_id, ctx, 0, duration_ms))
+        return { status: 'ok', call_id: call.call_id, tool_name: 'cpp.clangd', output: { ...result, diagnostic_ids: diag_ids }, metadata: { timestamp: new Date().toISOString(), command_run_id: cmd_id } }
       } else {
-        return { status: 'error', call_id: call.call_id, tool_name: 'cpp.clangd', error: { error_id: call.call_id, kind: 'tool_error', severity: 'error', message: result.error || 'clangd query failed', retryability: 'not_retryable', semantic_signature: 'cpp.clangd' }, metadata: { timestamp: new Date().toISOString() } }
+        await this.emit(event_sink, ctx, this.command_failed(cmd_id, ctx, 1, duration_ms, '', '', []))
+        await this.emit_evidence(event_sink, ctx, cmd_id, 'other', { error: result.error })
+        return { status: 'error', call_id: call.call_id, tool_name: 'cpp.clangd', error: { error_id: call.call_id, kind: 'tool_error', severity: 'error', message: result.error || 'clangd query failed', retryability: 'not_retryable', semantic_signature: 'cpp.clangd' }, metadata: { timestamp: new Date().toISOString(), command_run_id: cmd_id } }
       }
     })
   }
+
+  // ===== Private: event emission (no runtime import — uses duck-typed EventSink) =====
+
+  private cmd_id(): string {
+    return `cmd_${randomUUID().slice(0, 12)}`
+  }
+
+  private async emit(sink: EventSink | undefined, ctx: CppContext, event: any): Promise<void> {
+    if (!sink) return
+    try {
+      await sink.ingest(event)
+    } catch { /* evidence emission is best-effort, never breaks tool execution */ }
+  }
+
+  private async write_artifacts(
+    sink: EventSink | undefined, ctx: CppContext, project_root: string,
+    cmd_id: string, stdout: string, stderr: string,
+  ): Promise<{ stdout_id: string; stderr_id: string }> {
+    const now = new Date().toISOString()
+    const artifacts_dir = join(project_root, '.air', 'local', 'artifacts')
+    if (!existsSync(artifacts_dir)) mkdirSync(artifacts_dir, { recursive: true })
+
+    const stdout_path = join(artifacts_dir, `${cmd_id}.stdout.log`)
+    const stderr_path = join(artifacts_dir, `${cmd_id}.stderr.log`)
+
+    writeFileSync(stdout_path, stdout.slice(0, 65536), 'utf-8')
+    writeFileSync(stderr_path, stderr.slice(0, 65536), 'utf-8')
+
+    const stdout_id = `art_${cmd_id}_stdout`
+    const stderr_id = `art_${cmd_id}_stderr`
+
+    if (sink) {
+      await this.emit(sink, ctx, {
+        id: `evt_${stdout_id}`, type: 'artifact.created', version: 1, timestamp: now,
+        session_id: ctx.session_id, project_id: ctx.project_id,
+        source: { kind: 'tool' }, route: ['cpp', 'tool'],
+        payload: { artifact_id: stdout_id, type: 'log', uri: `file://${stdout_path}`, path: stdout_path, original_name: `${cmd_id}.stdout.log`, size_bytes: stdout.length, sha256: '', task_id: ctx.task_id || '', agent_id: ctx.agent_id || '', tool_run_id: ctx.tool_run_id || '', command_run_id: cmd_id, associated_entity_type: 'command_run', associated_entity_id: cmd_id, metadata: {} }
+      })
+      await this.emit(sink, ctx, {
+        id: `evt_${stderr_id}`, type: 'artifact.created', version: 1, timestamp: now,
+        session_id: ctx.session_id, project_id: ctx.project_id,
+        source: { kind: 'tool' }, route: ['cpp', 'tool'],
+        payload: { artifact_id: stderr_id, type: 'log', uri: `file://${stderr_path}`, path: stderr_path, original_name: `${cmd_id}.stderr.log`, size_bytes: stderr.length, sha256: '', task_id: ctx.task_id || '', agent_id: ctx.agent_id || '', tool_run_id: ctx.tool_run_id || '', command_run_id: cmd_id, associated_entity_type: 'command_run', associated_entity_id: cmd_id, metadata: {} }
+      })
+    }
+
+    return { stdout_id, stderr_id }
+  }
+
+  private async emit_diagnostics(
+    sink: EventSink | undefined, ctx: CppContext, cmd_id: string,
+    diags: Array<{ file: string; line: number; column: number; severity: string; message: string; semantic_signature: string }>,
+  ): Promise<string[]> {
+    if (!sink || diags.length === 0) return []
+    const now = new Date().toISOString()
+    const ids: string[] = []
+    for (let i = 0; i < diags.length; i++) {
+      const d = diags[i]
+      const did = `diag_${cmd_id}_${i}`
+      ids.push(did)
+      try {
+        await sink.ingest({
+          id: `evt_${did}`, type: 'diagnostic.created', version: 1, timestamp: now,
+          session_id: ctx.session_id, project_id: ctx.project_id,
+          source: { kind: 'tool' }, route: ['cpp', 'tool'],
+          payload: {
+            diagnostic_id: did, task_id: ctx.task_id || '', agent_id: ctx.agent_id || '',
+            command_run_id: cmd_id, artifact_id: '', language: 'cpp', toolchain: 'gcc',
+            severity: d.severity, file: d.file, line: d.line, column: d.column,
+            code: '', message: d.message, semantic_signature: d.semantic_signature, metadata: {},
+          }
+        })
+      } catch { /* diagnostic ingestion is best-effort */ }
+    }
+    return ids
+  }
+
+  private async emit_evidence(sink: EventSink | undefined, ctx: CppContext, cmd_id: string, kind: string, extra: any): Promise<void> {
+    if (!sink || !ctx.task_id) return
+    try {
+      await sink.ingest({
+        id: `evt_evr_${cmd_id}`, type: 'evidence.created', version: 1,
+        timestamp: new Date().toISOString(), session_id: ctx.session_id, project_id: ctx.project_id,
+        source: { kind: 'tool' }, route: ['cpp', 'tool'],
+        payload: {
+          evidence_ref_id: `evr_${cmd_id}`, kind, ref: `command_run:${cmd_id}`,
+          location_json: {}, claim: JSON.stringify(extra),
+          task_id: ctx.task_id, agent_id: ctx.agent_id || '', tool_run_id: ctx.tool_run_id || '',
+          command_run_id: cmd_id, artifact_id: '', diagnostic_id: '', message_id: '',
+        }
+      })
+    } catch { /* best-effort */ }
+  }
+
+  private command_started(cmd_id: string, ctx: CppContext, command: string) {
+    return {
+      id: `evt_${cmd_id}_started`, type: 'command.started', version: 1,
+      timestamp: new Date().toISOString(), session_id: ctx.session_id, project_id: ctx.project_id,
+      source: { kind: 'tool' }, route: ['cpp', 'tool'],
+      payload: { command_run_id: cmd_id, task_id: ctx.task_id || '', agent_id: ctx.agent_id || '', origin_message_id: '', tool_run_id: ctx.tool_run_id || '', command, cwd: ctx.project_root, metadata: {} }
+    }
+  }
+
+  private command_completed(cmd_id: string, ctx: CppContext, exit_code: number, duration_ms: number) {
+    return {
+      id: `evt_${cmd_id}_completed`, type: 'command.completed', version: 1,
+      timestamp: new Date().toISOString(), session_id: ctx.session_id, project_id: ctx.project_id,
+      source: { kind: 'tool' }, route: ['cpp', 'tool'],
+      payload: { command_run_id: cmd_id, exit_code, duration_ms, stdout_artifact_id: '', stderr_artifact_id: '', combined_artifact_id: '', diagnostic_ids: [], parsed_diagnostics_json: {}, metadata: {} }
+    }
+  }
+
+  private command_failed(cmd_id: string, ctx: CppContext, exit_code: number, duration_ms: number, stdout_artifact_id: string, stderr_artifact_id: string, diagnostic_ids: string[]) {
+    return {
+      id: `evt_${cmd_id}_failed`, type: 'command.failed', version: 1,
+      timestamp: new Date().toISOString(), session_id: ctx.session_id, project_id: ctx.project_id,
+      source: { kind: 'tool' }, route: ['cpp', 'tool'],
+      payload: { command_run_id: cmd_id, exit_code, duration_ms, stdout_artifact_id, stderr_artifact_id, combined_artifact_id: '', error: {}, evidence_refs: [], metadata: {} }
+    }
+  }
 }