diff --git a/packages/context/src/ingest/isolated-diff/git-patch.test.ts b/packages/context/src/ingest/isolated-diff/git-patch.test.ts
index fb92016f..2a48ce9b 100644
--- a/packages/context/src/ingest/isolated-diff/git-patch.test.ts
+++ b/packages/context/src/ingest/isolated-diff/git-patch.test.ts
@@ -50,6 +50,22 @@ describe('isolated diff patch contract', () => {
     ).toThrow(/slDisallowed WorkUnit lookml-mismatch touched semantic-layer\/c1\/orders.yaml/);
   });
 
+  it('rejects semantic-layer paths outside allowed target connections', () => {
+    const patch =
+      'diff --git a/semantic-layer/finance/orders.yaml b/semantic-layer/finance/orders.yaml\nindex 1..2 100644\n';
+
+    expect(() =>
+      assertPatchAllowedForWorkUnit({
+        unitKey: 'wu-finance',
+        patch,
+        slDisallowed: false,
+        allowedTargetConnectionIds: new Set(['warehouse']),
+      }),
+    ).toThrow(
+      /semantic-layer target connection not allowed: semantic-layer\/finance\/orders.yaml \(finance\); allowed: warehouse/,
+    );
+  });
+
   it('rejects executable and binary changes under known text artifact roots', () => {
     expect(textArtifactRoots).toEqual(['wiki/', 'semantic-layer/']);
 
diff --git a/packages/context/src/ingest/isolated-diff/git-patch.ts b/packages/context/src/ingest/isolated-diff/git-patch.ts
index 451d448a..ee7f0020 100644
--- a/packages/context/src/ingest/isolated-diff/git-patch.ts
+++ b/packages/context/src/ingest/isolated-diff/git-patch.ts
@@ -1,3 +1,5 @@
+import { assertSemanticLayerTargetPathsAllowed } from '../semantic-layer-target-policy.js';
+
 export const textArtifactRoots = ['wiki/', 'semantic-layer/'] as const;
 
 export interface PatchTouchedPath {
@@ -12,6 +14,7 @@ export interface PatchPolicyInput {
   unitKey: string;
   patch: string;
   slDisallowed: boolean;
+  allowedTargetConnectionIds?: ReadonlySet<string>;
 }
 
 function stripPrefix(path: string): string {
@@ -74,6 +77,12 @@ export function parsePatchTouchedPaths(patch: string): PatchTouchedPath[] {
 
 export function assertPatchAllowedForWorkUnit(input: PatchPolicyInput): PatchTouchedPath[] {
   const touched = parsePatchTouchedPaths(input.patch);
+  if (input.allowedTargetConnectionIds) {
+    assertSemanticLayerTargetPathsAllowed({
+      paths: touched.map((entry) => entry.path),
+      allowedConnectionIds: input.allowedTargetConnectionIds,
+    });
+  }
   for (const entry of touched) {
     if (input.slDisallowed && entry.path.startsWith('semantic-layer/')) {
       throw new Error(`slDisallowed WorkUnit ${input.unitKey} touched ${entry.path}`);
diff --git a/packages/context/src/ingest/semantic-layer-target-policy.test.ts b/packages/context/src/ingest/semantic-layer-target-policy.test.ts
new file mode 100644
index 00000000..73d09dc0
--- /dev/null
+++ b/packages/context/src/ingest/semantic-layer-target-policy.test.ts
@@ -0,0 +1,38 @@
+import { describe, expect, it } from 'vitest';
+import {
+  assertSemanticLayerTargetPathsAllowed,
+  findDisallowedSemanticLayerTargetPaths,
+  semanticLayerConnectionIdFromPath,
+} from './semantic-layer-target-policy.js';
+
+describe('semantic-layer target policy', () => {
+  it('extracts connection ids from semantic-layer paths', () => {
+    expect(semanticLayerConnectionIdFromPath('semantic-layer/warehouse/orders.yaml')).toBe('warehouse');
+    expect(semanticLayerConnectionIdFromPath('a/semantic-layer/finance/orders.yaml')).toBe('finance');
+    expect(semanticLayerConnectionIdFromPath('wiki/global/orders.md')).toBeNull();
+  });
+
+  it('finds semantic-layer paths outside the allowed target connections', () => {
+    expect(
+      findDisallowedSemanticLayerTargetPaths({
+        paths: [
+          'semantic-layer/warehouse/orders.yaml',
+          'semantic-layer/finance/orders.yaml',
+          'wiki/global/orders.md',
+        ],
+        allowedConnectionIds: new Set(['warehouse']),
+      }),
+    ).toEqual([{ path: 'semantic-layer/finance/orders.yaml', connectionId: 'finance' }]);
+  });
+
+  it('throws a deterministic error for unauthorized semantic-layer targets', () => {
+    expect(() =>
+      assertSemanticLayerTargetPathsAllowed({
+        paths: ['semantic-layer/finance/orders.yaml', 'semantic-layer/marketing/accounts.yaml'],
+        allowedConnectionIds: new Set(['warehouse']),
+      }),
+    ).toThrow(
+      /semantic-layer target connection not allowed: semantic-layer\/finance\/orders\.yaml \(finance\), semantic-layer\/marketing\/accounts\.yaml \(marketing\); allowed: warehouse/,
+    );
+  });
+});
diff --git a/packages/context/src/ingest/semantic-layer-target-policy.ts b/packages/context/src/ingest/semantic-layer-target-policy.ts
new file mode 100644
index 00000000..adf63b3b
--- /dev/null
+++ b/packages/context/src/ingest/semantic-layer-target-policy.ts
@@ -0,0 +1,42 @@
+export interface SemanticLayerTargetPolicyInput {
+  paths: readonly string[];
+  allowedConnectionIds: ReadonlySet<string>;
+}
+
+export interface SemanticLayerTargetPolicyViolation {
+  path: string;
+  connectionId: string;
+}
+
+export function semanticLayerConnectionIdFromPath(path: string): string | null {
+  const normalized = path.replace(/^[ab]\//, '');
+  const match = /^semantic-layer\/([^/]+)\//.exec(normalized);
+  return match?.[1] ?? null;
+}
+
+export function findDisallowedSemanticLayerTargetPaths(
+  input: SemanticLayerTargetPolicyInput,
+): SemanticLayerTargetPolicyViolation[] {
+  return input.paths
+    .map((path) => ({ path, connectionId: semanticLayerConnectionIdFromPath(path) }))
+    .filter((entry): entry is SemanticLayerTargetPolicyViolation => {
+      return entry.connectionId !== null && !input.allowedConnectionIds.has(entry.connectionId);
+    })
+    .sort((left, right) => {
+      const byConnection = left.connectionId.localeCompare(right.connectionId);
+      return byConnection === 0 ? left.path.localeCompare(right.path) : byConnection;
+    });
+}
+
+export function assertSemanticLayerTargetPathsAllowed(input: SemanticLayerTargetPolicyInput): void {
+  const violations = findDisallowedSemanticLayerTargetPaths(input);
+  if (violations.length === 0) {
+    return;
+  }
+  const allowed = [...input.allowedConnectionIds].sort();
+  throw new Error(
+    `semantic-layer target connection not allowed: ${violations
+      .map((violation) => `${violation.path} (${violation.connectionId})`)
+      .join(', ')}; allowed: ${allowed.length > 0 ? allowed.join(', ') : '(none)'}`,
+  );
+}
diff --git a/packages/context/src/sl/tools/sl-edit-source.tool.test.ts b/packages/context/src/sl/tools/sl-edit-source.tool.test.ts
index 49a8f757..75c753ef 100644
--- a/packages/context/src/sl/tools/sl-edit-source.tool.test.ts
+++ b/packages/context/src/sl/tools/sl-edit-source.tool.test.ts
@@ -99,6 +99,27 @@ describe('SlEditSourceTool — session gating', () => {
     );
   });
 
+  it('rejects session-scoped edits outside allowed target connections', async () => {
+    const { tool } = makeTool();
+    const session = makeSession({
+      allowedConnectionNames: new Set(['warehouse']),
+    });
+    const context: ToolContext = { ...baseContext, session };
+
+    const result = await tool.call(
+      {
+        connectionId: 'finance',
+        sourceName: 'orders',
+        yaml_edits: [{ oldText: 'measures: []', newText: 'measures: []' }],
+      } as any,
+      context,
+    );
+
+    expect(result.structured.success).toBe(false);
+    expect(result.markdown).toContain('connectionId "finance" is outside this ingest session');
+    expect(session.actions).toEqual([]);
+  });
+
   it('indexes normally when no session is present', async () => {
     const { tool, slSearchService } = makeTool();
     const result = await tool.call(
diff --git a/packages/context/src/sl/tools/sl-edit-source.tool.ts b/packages/context/src/sl/tools/sl-edit-source.tool.ts
index 813072c0..f6669120 100644
--- a/packages/context/src/sl/tools/sl-edit-source.tool.ts
+++ b/packages/context/src/sl/tools/sl-edit-source.tool.ts
@@ -1,6 +1,12 @@
 import YAML from 'yaml';
 import { z } from 'zod';
-import { addTouchedSlSource, type ToolContext, type ToolOutput, validateActionRawPaths } from '../../tools/index.js';
+import {
+  addTouchedSlSource,
+  type ToolContext,
+  type ToolOutput,
+  validateActionRawPaths,
+  validateActionTargetConnection,
+} from '../../tools/index.js';
 import { applySqlEdits } from '../../tools/sql-edit-replacer.js';
 import { normalizeSemanticLayerDescriptions } from '../description-normalization.js';
 import type { SemanticLayerSource } from '../types.js';
@@ -79,6 +85,10 @@ If no source exists yet, use sl_write_source instead — this tool will reject t
 
     const semanticLayerService = context.session?.semanticLayerService ?? this.semanticLayerService;
     const skipIndex = context.session?.isWorktreeScoped === true;
+    const targetConnectionValidation = validateActionTargetConnection(context.session, connectionId);
+    if (!targetConnectionValidation.ok) {
+      return this.buildOutput(false, [targetConnectionValidation.error], sourceName);
+    }
     const rawPathValidation = validateActionRawPaths(context.session, input.rawPaths);
     if (!rawPathValidation.ok) {
       return this.buildOutput(false, [rawPathValidation.error], sourceName);
diff --git a/packages/context/src/sl/tools/sl-write-source.tool.test.ts b/packages/context/src/sl/tools/sl-write-source.tool.test.ts
index 6f9cdbc0..186028b8 100644
--- a/packages/context/src/sl/tools/sl-write-source.tool.test.ts
+++ b/packages/context/src/sl/tools/sl-write-source.tool.test.ts
@@ -133,6 +133,34 @@ describe('SlWriteSourceTool — session gating', () => {
     );
   });
 
+  it('rejects session-scoped writes outside allowed target connections', async () => {
+    const { tool } = makeTool();
+    const session = makeSession({
+      allowedConnectionNames: new Set(['warehouse']),
+    });
+    const context: ToolContext = { ...baseContext, session };
+
+    const result = await tool.call(
+      {
+        connectionId: 'finance',
+        sourceName: 'finance_orders',
+        source: {
+          name: 'finance_orders',
+          table: 'public.orders',
+          grain: ['id'],
+          columns: [{ name: 'id', type: 'string' }],
+          measures: [],
+          joins: [],
+        } as any,
+      } as any,
+      context,
+    );
+
+    expect(result.structured.success).toBe(false);
+    expect(result.markdown).toContain('connectionId "finance" is outside this ingest session');
+    expect(session.actions).toEqual([]);
+  });
+
   it('indexes normally when no session is present', async () => {
     const { tool, slSearchService } = makeTool();
     const result = await tool.call(
diff --git a/packages/context/src/sl/tools/sl-write-source.tool.ts b/packages/context/src/sl/tools/sl-write-source.tool.ts
index 357e7ca0..b9a79e6b 100644
--- a/packages/context/src/sl/tools/sl-write-source.tool.ts
+++ b/packages/context/src/sl/tools/sl-write-source.tool.ts
@@ -1,6 +1,12 @@
 import YAML from 'yaml';
 import { z } from 'zod';
-import { addTouchedSlSource, type ToolContext, type ToolOutput, validateActionRawPaths } from '../../tools/index.js';
+import {
+  addTouchedSlSource,
+  type ToolContext,
+  type ToolOutput,
+  validateActionRawPaths,
+  validateActionTargetConnection,
+} from '../../tools/index.js';
 import { sourceOverlaySchema } from '../schemas.js';
 import type { SemanticLayerService } from '../semantic-layer.service.js';
 import type { SemanticLayerSource } from '../types.js';
@@ -106,6 +112,10 @@ Do NOT join back to a table that the SQL already aggregates from if the grain co
 
     const semanticLayerService = context.session?.semanticLayerService ?? this.semanticLayerService;
     const skipIndex = context.session?.isWorktreeScoped === true;
+    const targetConnectionValidation = validateActionTargetConnection(context.session, connectionId);
+    if (!targetConnectionValidation.ok) {
+      return this.buildOutput(false, [targetConnectionValidation.error], sourceName);
+    }
     const rawPathValidation = validateActionRawPaths(context.session, input.rawPaths);
     if (!rawPathValidation.ok) {
       return this.buildOutput(false, [rawPathValidation.error], sourceName);
diff --git a/packages/context/src/tools/action-target-connection.ts b/packages/context/src/tools/action-target-connection.ts
new file mode 100644
index 00000000..4ba3f651
--- /dev/null
+++ b/packages/context/src/tools/action-target-connection.ts
@@ -0,0 +1,23 @@
+import type { ToolSession } from './tool-session.js';
+
+type ActionTargetConnectionValidation = { ok: true } | { ok: false; error: string };
+
+export function validateActionTargetConnection(
+  session: ToolSession | undefined,
+  connectionId: string,
+): ActionTargetConnectionValidation {
+  const allowed = session?.allowedConnectionNames;
+  if (!allowed) {
+    return { ok: true };
+  }
+  if (allowed.has(connectionId)) {
+    return { ok: true };
+  }
+  const allowedList = [...allowed].sort();
+  return {
+    ok: false,
+    error: `connectionId "${connectionId}" is outside this ingest session's allowed target connections: ${
+      allowedList.length > 0 ? allowedList.join(', ') : '(none)'
+    }`,
+  };
+}
diff --git a/packages/context/src/tools/index.ts b/packages/context/src/tools/index.ts
index a3fc5e7b..c6a334d5 100644
--- a/packages/context/src/tools/index.ts
+++ b/packages/context/src/tools/index.ts
@@ -32,6 +32,7 @@ export type { SqlEdit } from './sql-edit-replacer.js';
 export { applySqlEdits } from './sql-edit-replacer.js';
 export type { IngestToolMetadata, MemoryAction, ToolSession } from './tool-session.js';
 export { validateActionRawPaths } from './action-raw-paths.js';
+export { validateActionTargetConnection } from './action-target-connection.js';
 export type { TouchedSlSource, TouchedSlSourceSet } from './touched-sl-sources.js';
 export {
   addTouchedSlSource,