diff --git a/packages/context/src/ingest/ingest-bundle.runner.test.ts b/packages/context/src/ingest/ingest-bundle.runner.test.ts
index dc48b18c..6134fbe7 100644
--- a/packages/context/src/ingest/ingest-bundle.runner.test.ts
+++ b/packages/context/src/ingest/ingest-bundle.runner.test.ts
@@ -675,6 +675,14 @@ describe('IngestBundleRunner — Stages 1 → 7', () => {
         });
       }
       if (params.telemetryTags.operationName === 'ingest-bundle-reconcile') {
+        await params.toolSet.record_verification_ledger.execute(
+          {
+            summary: 'Reconciliation emits no warehouse identifiers before fallback recording.',
+            verifiedIdentifiers: [],
+            unverifiedIdentifiers: [],
+          },
+          { toolCallId: 'ledger-1', messages: [] },
+        );
         await params.toolSet.emit_conflict_resolution.execute(
           {
             kind: 'near_duplicate',
@@ -843,6 +851,14 @@ describe('IngestBundleRunner — Stages 1 → 7', () => {
           { path: 'a.yml', startLine: 1, endLine: 2 },
           { toolCallId: 'read-1', messages: [] },
         );
+        await params.toolSet.record_verification_ledger.execute(
+          {
+            summary: 'Wiki write contains no warehouse identifiers.',
+            verifiedIdentifiers: [],
+            unverifiedIdentifiers: [],
+          },
+          { toolCallId: 'ledger-1', messages: [] },
+        );
         await params.toolSet.wiki_write.execute(
           { key: 'knowledge/a.md', content: 'safe summary' },
           { toolCallId: 'wiki-1', messages: [] },
@@ -882,9 +898,9 @@ describe('IngestBundleRunner — Stages 1 → 7', () => {
             {
               unitKey: 'u1',
               path: '/tmp/ktx-test/run/wu-transcripts/j1/u1.jsonl',
-              toolCallCount: 2,
+              toolCallCount: 3,
               errorCount: 0,
-              toolNames: ['read_raw_span', 'wiki_write'],
+              toolNames: ['read_raw_span', 'record_verification_ledger', 'wiki_write'],
             },
           ],
         }),
@@ -896,6 +912,14 @@ describe('IngestBundleRunner — Stages 1 → 7', () => {
     const deps = makeDeps();
     deps.agentRunner.runLoop.mockImplementation(async (params: any) => {
       if (params.telemetryTags.operationName === 'ingest-bundle-wu') {
+        await params.toolSet.record_verification_ledger.execute(
+          {
+            summary: 'Unmapped fallback records an unsupported conversion metric without verified warehouse identifiers.',
+            verifiedIdentifiers: [],
+            unverifiedIdentifiers: [],
+          },
+          { toolCallId: 'ledger-1', messages: [] },
+        );
         await params.toolSet.emit_unmapped_fallback.execute(
           {
             rawPath: 'a.yml',
@@ -952,6 +976,14 @@ describe('IngestBundleRunner — Stages 1 → 7', () => {
     });
     deps.agentRunner.runLoop.mockImplementation(async (params: any) => {
       if (params.telemetryTags.operationName === 'ingest-bundle-reconcile') {
+        await params.toolSet.record_verification_ledger.execute(
+          {
+            summary: 'Reconciliation records conflict, eviction, and fallback decisions without warehouse identifiers.',
+            verifiedIdentifiers: [],
+            unverifiedIdentifiers: [],
+          },
+          { toolCallId: 'ledger-1', messages: [] },
+        );
         await params.toolSet.emit_conflict_resolution.execute(
           {
             kind: 'near_duplicate',
diff --git a/packages/context/src/ingest/stages/build-reconcile-context.test.ts b/packages/context/src/ingest/stages/build-reconcile-context.test.ts
index 7db0bb23..9ac95356 100644
--- a/packages/context/src/ingest/stages/build-reconcile-context.test.ts
+++ b/packages/context/src/ingest/stages/build-reconcile-context.test.ts
@@ -107,6 +107,7 @@ describe('buildReconcileToolSet', () => {
         'eviction_list',
         'load_skill',
         'read_raw_span',
+        'record_verification_ledger',
         'sl_write_source',
         'stage_diff',
         'stage_list',
@@ -114,4 +115,54 @@ describe('buildReconcileToolSet', () => {
       ].sort(),
     );
   });
+
+  it('requires the verification ledger before reconciliation write tools run', async () => {
+    const slWrite = vi.fn().mockResolvedValue({ markdown: 'written', structured: { success: true } });
+    const toolSet = buildReconcileToolSet({
+      loadSkillTool: { load_skill: { description: 'load', inputSchema: {} as any, execute: vi.fn() } } as any,
+      stageListTool: { stage_list: { description: 'stage list', inputSchema: {} as any, execute: vi.fn() } } as any,
+      stageDiffTool: { stage_diff: { description: 'stage diff', inputSchema: {} as any, execute: vi.fn() } } as any,
+      evictionListTool: {
+        eviction_list: { description: 'eviction list', inputSchema: {} as any, execute: vi.fn() },
+      } as any,
+      emitConflictResolutionTool: {
+        emit_conflict_resolution: { description: 'conflict', inputSchema: {} as any, execute: vi.fn() },
+      } as any,
+      emitEvictionDecisionTool: {
+        emit_eviction_decision: { description: 'eviction', inputSchema: {} as any, execute: vi.fn() },
+      } as any,
+      emitArtifactResolutionTool: {
+        emit_artifact_resolution: { description: 'resolution', inputSchema: {} as any, execute: vi.fn() },
+      } as any,
+      emitUnmappedFallbackTool: {
+        emit_unmapped_fallback: { description: 'fallback', inputSchema: {} as any, execute: vi.fn() },
+      } as any,
+      readRawSpanTool: { read_raw_span: { description: 'raw span', inputSchema: {} as any, execute: vi.fn() } } as any,
+      toolsetTools: { sl_write_source: { description: 'sl write', inputSchema: {} as any, execute: slWrite } as any },
+    });
+
+    const correction = await toolSet.sl_write_source.execute?.(
+      { connectionId: 'warehouse', sourceName: 'accounts' },
+      { toolCallId: 't1' } as any,
+    );
+
+    expect(slWrite).not.toHaveBeenCalled();
+    expect(correction).toMatchObject({ structured: { success: false, reason: 'verification_ledger_required' } });
+
+    await toolSet.record_verification_ledger.execute?.(
+      {
+        summary: 'Verified warehouse.accounts with entity_details.',
+        verifiedIdentifiers: ['warehouse.accounts'],
+        unverifiedIdentifiers: [],
+      },
+      { toolCallId: 't2' } as any,
+    );
+    const written = await toolSet.sl_write_source.execute?.(
+      { connectionId: 'warehouse', sourceName: 'accounts' },
+      { toolCallId: 't3' } as any,
+    );
+
+    expect(slWrite).toHaveBeenCalledTimes(1);
+    expect(written).toMatchObject({ structured: { success: true } });
+  });
 });
diff --git a/packages/context/src/ingest/stages/build-reconcile-context.ts b/packages/context/src/ingest/stages/build-reconcile-context.ts
index 30ff6341..9533acbd 100644
--- a/packages/context/src/ingest/stages/build-reconcile-context.ts
+++ b/packages/context/src/ingest/stages/build-reconcile-context.ts
@@ -1,5 +1,10 @@
 import type { Tool, ToolSet } from 'ai';
 import { buildCanonicalPinsPromptBlock, type CanonicalPin } from '../canonical-pins.js';
+import {
+  createVerificationLedgerState,
+  VERIFICATION_LEDGER_PROMPT,
+  withVerificationLedger,
+} from '../tools/verification-ledger.tool.js';
 import type { EvictionUnit } from '../types.js';
 import type { StageIndex } from './stage-index.types.js';
 
@@ -12,6 +17,7 @@ export function buildReconcileSystemPrompt(params: {
 }): string {
   return [
     params.baseFraming.trimEnd(),
+    VERIFICATION_LEDGER_PROMPT,
     params.skillsPrompt.trimEnd(),
     buildCanonicalPinsPromptBlock(params.canonicalPins),
     `\n<context>\nsyncId: ${params.syncId}\nsource: ${params.sourceKey}\n</context>`,
@@ -188,16 +194,20 @@ export interface ReconcileToolSetInput {
 }
 
 export function buildReconcileToolSet(input: ReconcileToolSetInput): ToolSet {
-  return {
-    ...input.toolsetTools,
-    ...input.loadSkillTool,
-    ...input.stageListTool,
-    ...input.stageDiffTool,
-    ...input.evictionListTool,
-    ...input.emitConflictResolutionTool,
-    ...input.emitEvictionDecisionTool,
-    ...input.emitArtifactResolutionTool,
-    ...input.emitUnmappedFallbackTool,
-    ...input.readRawSpanTool,
-  };
+  const state = createVerificationLedgerState();
+  return withVerificationLedger(
+    {
+      ...input.toolsetTools,
+      ...input.loadSkillTool,
+      ...input.stageListTool,
+      ...input.stageDiffTool,
+      ...input.evictionListTool,
+      ...input.emitConflictResolutionTool,
+      ...input.emitEvictionDecisionTool,
+      ...input.emitArtifactResolutionTool,
+      ...input.emitUnmappedFallbackTool,
+      ...input.readRawSpanTool,
+    },
+    state,
+  );
 }
diff --git a/packages/context/src/ingest/stages/build-wu-context.test.ts b/packages/context/src/ingest/stages/build-wu-context.test.ts
index 13a3ff8f..db17154e 100644
--- a/packages/context/src/ingest/stages/build-wu-context.test.ts
+++ b/packages/context/src/ingest/stages/build-wu-context.test.ts
@@ -68,12 +68,45 @@ describe('buildWuToolSet', () => {
         'load_skill',
         'read_raw_file',
         'read_raw_span',
+        'record_verification_ledger',
         'sl_write_source',
         'wiki_search',
       ].sort(),
     );
   });
 
+  it('requires the verification ledger before write-capable tools run', async () => {
+    const wikiWrite = vi.fn().mockResolvedValue({ markdown: 'written', structured: { success: true } });
+    const toolSet = buildWuToolSet({
+      stagedDir: '/tmp/staged',
+      wu: { unitKey: 'u1', rawFiles: ['a.yml'], peerFileIndex: [], dependencyPaths: [] },
+      loadSkillTool: { load_skill: { description: 'load', inputSchema: {} as any, execute: vi.fn() } } as any,
+      emitUnmappedFallbackTool: {
+        emit_unmapped_fallback: { description: 'fallback', inputSchema: {} as any, execute: vi.fn() },
+      } as any,
+      toolsetTools: { wiki_write: { description: 'write', inputSchema: {} as any, execute: wikiWrite } as any },
+    });
+
+    const correction = await toolSet.wiki_write.execute?.({ key: 'customer-rules' }, { toolCallId: 't1' } as any);
+
+    expect(wikiWrite).not.toHaveBeenCalled();
+    expect(correction).toMatchObject({ structured: { success: false, reason: 'verification_ledger_required' } });
+    expect(String((correction as any).markdown)).toContain('record_verification_ledger');
+
+    await toolSet.record_verification_ledger.execute?.(
+      {
+        summary: 'No warehouse identifiers will be emitted in this wiki write.',
+        verifiedIdentifiers: [],
+        unverifiedIdentifiers: [],
+      },
+      { toolCallId: 't2' } as any,
+    );
+    const written = await toolSet.wiki_write.execute?.({ key: 'customer-rules' }, { toolCallId: 't3' } as any);
+
+    expect(wikiWrite).toHaveBeenCalledTimes(1);
+    expect(written).toMatchObject({ structured: { success: true } });
+  });
+
   it('includes looker_query_to_sl only for Looker WorkUnits', () => {
     const toolSet = buildWuToolSet({
       sourceKey: 'looker',
@@ -93,6 +126,7 @@ describe('buildWuToolSet', () => {
         'looker_query_to_sl',
         'read_raw_file',
         'read_raw_span',
+        'record_verification_ledger',
         'sl_write_source',
         'wiki_search',
       ].sort(),
diff --git a/packages/context/src/ingest/stages/build-wu-context.ts b/packages/context/src/ingest/stages/build-wu-context.ts
index 6ba26fd7..bfa1bd9c 100644
--- a/packages/context/src/ingest/stages/build-wu-context.ts
+++ b/packages/context/src/ingest/stages/build-wu-context.ts
@@ -4,6 +4,11 @@ import { createLookerQueryToSlTool } from '../adapters/looker/tools/looker-query
 import type { IngestProvenanceRow } from '../ports.js';
 import { createReadRawFileTool } from '../tools/read-raw-file.tool.js';
 import { createReadRawSpanTool } from '../tools/read-raw-span.tool.js';
+import {
+  createVerificationLedgerState,
+  VERIFICATION_LEDGER_PROMPT,
+  withVerificationLedger,
+} from '../tools/verification-ledger.tool.js';
 import type { WorkUnit } from '../types.js';
 
 const PEER_FILE_INDEX_PROMPT_LIMIT = 100;
@@ -24,6 +29,7 @@ export function buildWuSystemPrompt(params: {
 }): string {
   const parts = [
     params.baseFraming.trimEnd(),
+    VERIFICATION_LEDGER_PROMPT,
     params.skillsPrompt.trimEnd(),
     buildCanonicalPinsPromptBlock(params.canonicalPins ?? []),
     `\n<context>\nsyncId: ${params.syncId}\nsource: ${params.sourceKey}\n</context>`,
@@ -100,15 +106,19 @@ function withoutWriteSlTools(toolset: ToolSet, wu: WorkUnit): ToolSet {
 export function buildWuToolSet(input: BuildWuToolSetInput): ToolSet {
   const allowedPaths = new Set<string>([...input.wu.rawFiles, ...input.wu.dependencyPaths]);
   const lookerTools: ToolSet = input.sourceKey === 'looker' ? { looker_query_to_sl: createLookerQueryToSlTool() } : {};
-  return withoutWriteSlTools(
-    {
-      ...input.toolsetTools,
-      ...lookerTools,
-      ...input.loadSkillTool,
-      ...input.emitUnmappedFallbackTool,
-      read_raw_file: createReadRawFileTool({ stagedDir: input.stagedDir, allowedPaths }),
-      read_raw_span: createReadRawSpanTool({ stagedDir: input.stagedDir, allowedPaths }),
-    },
-    input.wu,
+  const state = createVerificationLedgerState();
+  return withVerificationLedger(
+    withoutWriteSlTools(
+      {
+        ...input.toolsetTools,
+        ...lookerTools,
+        ...input.loadSkillTool,
+        ...input.emitUnmappedFallbackTool,
+        read_raw_file: createReadRawFileTool({ stagedDir: input.stagedDir, allowedPaths }),
+        read_raw_span: createReadRawSpanTool({ stagedDir: input.stagedDir, allowedPaths }),
+      },
+      input.wu,
+    ),
+    state,
   );
 }
diff --git a/packages/context/src/ingest/tools/verification-ledger.tool.ts b/packages/context/src/ingest/tools/verification-ledger.tool.ts
new file mode 100644
index 00000000..f99e79be
--- /dev/null
+++ b/packages/context/src/ingest/tools/verification-ledger.tool.ts
@@ -0,0 +1,97 @@
+import { tool, type ToolExecuteFunction, type ToolExecutionOptions, type ToolSet } from 'ai';
+import { z } from 'zod';
+
+const verificationLedgerInputSchema = z.object({
+  summary: z.string().min(1).max(2000),
+  verifiedIdentifiers: z.array(z.string().min(1)).max(100).default([]),
+  unverifiedIdentifiers: z.array(z.string().min(1)).max(100).default([]),
+  notes: z.string().max(2000).optional(),
+});
+
+export interface VerificationLedgerEntry {
+  summary: string;
+  verifiedIdentifiers: string[];
+  unverifiedIdentifiers: string[];
+  notes?: string;
+}
+
+export interface VerificationLedgerState {
+  entries: VerificationLedgerEntry[];
+}
+
+const WRITE_TOOL_NAMES = new Set([
+  'wiki_write',
+  'wiki_remove',
+  'sl_write_source',
+  'sl_edit_source',
+  'emit_unmapped_fallback',
+]);
+
+export const VERIFICATION_LEDGER_PROMPT = `<pre_write_verification>
+Before any write-capable tool call (wiki_write, wiki_remove, sl_write_source, sl_edit_source, emit_unmapped_fallback), call record_verification_ledger.
+The ledger is a model-authored checkpoint, not a deterministic parser gate. Summarize the verification protocol from the loaded skill, list identifiers verified with discover_data/entity_details/sql_execution, and list anything intentionally left unverified. If the write contains no warehouse identifiers, say that explicitly.
+If a write tool returns verification_ledger_required, complete the ledger and retry the write.
+</pre_write_verification>`;
+
+export function createVerificationLedgerState(): VerificationLedgerState {
+  return { entries: [] };
+}
+
+export function withVerificationLedger(tools: ToolSet, state: VerificationLedgerState): ToolSet {
+  const wrapped: ToolSet = {};
+  for (const [name, original] of Object.entries(tools)) {
+    if (!WRITE_TOOL_NAMES.has(name) || typeof original.execute !== 'function') {
+      wrapped[name] = original;
+      continue;
+    }
+    const originalExecute = original.execute;
+    const guardedExecute: ToolExecuteFunction<unknown, unknown> = async (
+      input: unknown,
+      opts: ToolExecutionOptions,
+    ) => {
+      if (state.entries.length === 0) {
+        return verificationRequiredOutput(name);
+      }
+      return (originalExecute as ToolExecuteFunction<unknown, unknown>)(input, opts);
+    };
+    wrapped[name] = { ...original, execute: guardedExecute };
+  }
+  wrapped.record_verification_ledger = createRecordVerificationLedgerTool(state);
+  return wrapped;
+}
+
+function createRecordVerificationLedgerTool(state: VerificationLedgerState) {
+  return tool({
+    description:
+      'Record the pre-write verification ledger required by loaded ingest skills. Call this before wiki/SL/fallback writes to state what was verified, which tool calls support it, and what remains intentionally unverified.',
+    inputSchema: verificationLedgerInputSchema,
+    execute: async (input) => {
+      const entry = verificationLedgerInputSchema.parse(input);
+      state.entries.push(entry);
+      return {
+        markdown:
+          `Verification ledger recorded. Summary: ${entry.summary}\n` +
+          `Verified identifiers: ${entry.verifiedIdentifiers.length ? entry.verifiedIdentifiers.join(', ') : '(none)'}\n` +
+          `Unverified identifiers: ${
+            entry.unverifiedIdentifiers.length ? entry.unverifiedIdentifiers.join(', ') : '(none)'
+          }`,
+        structured: { success: true, entry },
+      };
+    },
+  });
+}
+
+function verificationRequiredOutput(toolName: string) {
+  return {
+    markdown:
+      `Pre-write verification required before calling ${toolName}. ` +
+      'Call record_verification_ledger first. In the ledger, summarize the loaded skill protocol you followed, ' +
+      'list identifiers verified via discover_data/entity_details/sql_execution, and list any identifiers intentionally left unverified. ' +
+      'If the write contains no warehouse identifiers, say that explicitly in the ledger summary.',
+    structured: {
+      success: false,
+      reason: 'verification_ledger_required',
+      toolName,
+    },
+  };
+}