feat(cli): bgagent linear remove-workspace + DELETE route + fail-closed resolver (#306)

cdk/src/constructs/linear-integration.ts

@@ -41,6 +41,12 @@ const WEBHOOK_PROCESSOR_TIMEOUT_SECONDS = 30;
 /** Webhook-processor Lambda memory (MB). */
 const WEBHOOK_PROCESSOR_MEMORY_MB = 512;
 
+/** Remove-workspace Lambda timeout (seconds). 10s matches the sibling
+ *  link/webhook request handlers — the teardown is a bounded sequence
+ *  (registry revoke → secret delete → optional row purge) with no
+ *  unbounded pagination. */
+const REMOVE_WORKSPACE_TIMEOUT_SECONDS = 10;
+
 /**
  * Properties for LinearIntegration construct.
  */
@@ -302,6 +308,42 @@ export class LinearIntegration extends Construct {
     });
     this.userMappingTable.grantReadWriteData(linkFn);
 
+    // --- Workspace removal (Cognito-authenticated, admin-only) ---
+    // Backs `bgagent linear remove-workspace <slug>`: revokes/purges the
+    // registry row and deletes the per-workspace OAuth secret. Keeping the
+    // DDB + Secrets Manager grants on this Lambda's role — not on every CLI
+    // user — is the whole point of routing removal through the API (see
+    // issue #306). Project mappings are intentionally NOT touched: mapping
+    // rows carry no workspace id, so they cannot be attributed to a
+    // workspace (removal is by project id).
+    const removeWorkspaceFn = new lambda.NodejsFunction(this, 'RemoveWorkspaceFn', {
+      entry: path.join(handlersDir, 'linear-remove-workspace.ts'),
+      handler: 'handler',
+      runtime: Runtime.NODEJS_24_X,
+      architecture: Architecture.ARM_64,
+      timeout: Duration.seconds(REMOVE_WORKSPACE_TIMEOUT_SECONDS),
+      environment: {
+        LINEAR_WORKSPACE_REGISTRY_TABLE_NAME: this.workspaceRegistryTable.tableName,
+      },
+      bundling: commonBundling,
+    });
+    this.workspaceRegistryTable.grantReadWriteData(removeWorkspaceFn);
+    // Delete the per-workspace OAuth secret created by the CLI at setup time
+    // (`bgagent-linear-oauth-<slug>`). The concrete name isn't known at synth
+    // time (operators add workspaces by slug at runtime), so scope to the
+    // documented prefix — same wildcard the webhook Lambdas already use.
+    removeWorkspaceFn.addToRolePolicy(new iam.PolicyStatement({
+      actions: ['secretsmanager:DeleteSecret'],
+      resources: [
+        Stack.of(this).formatArn({
+          service: 'secretsmanager',
+          resource: 'secret',
+          arnFormat: ArnFormat.COLON_RESOURCE_NAME,
+          resourceName: 'bgagent-linear-oauth-*',
+        }),
+      ],
+    }));
+
     // ═══════════════════════════════════════════════════════════════════════════
     // API Gateway Routes
     // ═══════════════════════════════════════════════════════════════════════════
@@ -324,6 +366,15 @@ export class LinearIntegration extends Construct {
       cognitoAuthOptions,
     );
 
+    // DELETE /v1/linear/workspaces/{slug} — Cognito-authenticated, admin-only.
+    const workspacesResource = linear.addResource('workspaces');
+    const workspaceBySlug = workspacesResource.addResource('{slug}');
+    workspaceBySlug.addMethod(
+      'DELETE',
+      new apigw.LambdaIntegration(removeWorkspaceFn),
+      cognitoAuthOptions,
+    );
+
     // ═══════════════════════════════════════════════════════════════════════════
     // cdk-nag suppressions
     // ═══════════════════════════════════════════════════════════════════════════
@@ -346,7 +397,7 @@ export class LinearIntegration extends Construct {
       },
     ]);
 
-    const allFunctions = [webhookFn, webhookProcessorFn, linkFn];
+    const allFunctions = [webhookFn, webhookProcessorFn, linkFn, removeWorkspaceFn];
     for (const fn of allFunctions) {
       NagSuppressions.addResourceSuppressions(fn, [
         {

cdk/src/handlers/linear-remove-workspace.ts

@@ -0,0 +1,288 @@
+/**
+ *  MIT No Attribution
+ *
+ *  Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy of
+ *  the Software without restriction, including without limitation the rights to
+ *  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ *  the Software, and to permit persons to whom the Software is furnished to do so.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ */
+
+import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
+import { DeleteSecretCommand, SecretsManagerClient } from '@aws-sdk/client-secrets-manager';
+import { DynamoDBDocumentClient, DeleteCommand, ScanCommand, UpdateCommand } from '@aws-sdk/lib-dynamodb';
+import type { APIGatewayProxyEvent, APIGatewayProxyResult } from 'aws-lambda';
+import { ulid } from 'ulid';
+import { extractUserId } from './shared/gateway';
+import { logger } from './shared/logger';
+import { ErrorCode, errorResponse, successResponse } from './shared/response';
+
+const ddb = DynamoDBDocumentClient.from(new DynamoDBClient({}));
+const sm = new SecretsManagerClient({});
+
+const WORKSPACE_REGISTRY_TABLE = process.env.LINEAR_WORKSPACE_REGISTRY_TABLE_NAME!;
+
+/** Same slug shape the CLI enforces (`SLUG_RE` in cli/src/commands/linear.ts). */
+const SLUG_RE = /^[a-zA-Z0-9_-]{4,50}$/;
+
+/**
+ * DELETE /v1/linear/workspaces/{slug} — deregister a Linear workspace.
+ *
+ * Cognito-authenticated. Only the workspace admin (the platform user who
+ * ran `bgagent linear setup`/`add-workspace` for the slug, recorded as
+ * `installed_by_platform_user_id`) may remove it.
+ *
+ * By default this is a *soft* removal that preserves the audit trail:
+ *   1. Flip the registry row to `status='revoked'` (the OAuth resolver
+ *      fail-closes on any status != 'active' — see
+ *      `shared/linear-oauth-resolver.ts`, so a revoked workspace can no
+ *      longer resolve a token and its inbound webhooks stop routing).
+ *   2. Delete the per-workspace `bgagent-linear-oauth-<slug>` secret so no
+ *      credential lingers.
+ *
+ * Query flag:
+ *   - `purge=true` — delete the registry row outright (no audit row).
+ *
+ * Idempotent on the secret: if the secret is already gone we report
+ * `secret_deleted: false` and still complete the revoke, so a retried or
+ * partially-completed removal converges cleanly.
+ *
+ * Project mappings are NOT touched here: `LinearProjectMappingTable` rows
+ * carry no workspace identifier (the `onboard-project` writer records only
+ * `linear_project_id`), so they cannot be attributed to a workspace. Removing
+ * a mapping is a by-project-id operation (see LINEAR_SETUP_GUIDE). A follow-up
+ * will record `linear_workspace_id` at onboard time to enable workspace-scoped
+ * cleanup.
+ */
+export async function handler(event: APIGatewayProxyEvent): Promise<APIGatewayProxyResult> {
+  const requestId = ulid();
+  // Outer-scope breadcrumbs so the top-level catch can name the workspace
+  // and the phase that failed — the difference between "which secret
+  // leaked?" being answerable from one log line vs. a manual hunt.
+  let slug = '';
+  let phase: 'lookup' | 'registry_write' | 'secret_delete' = 'lookup';
+
+  try {
+    const userId = extractUserId(event);
+    if (!userId) {
+      return errorResponse(401, ErrorCode.UNAUTHORIZED, 'Authentication required.', requestId);
+    }
+
+    slug = (event.pathParameters?.slug ?? '').trim();
+    if (!SLUG_RE.test(slug)) {
+      return errorResponse(
+        400,
+        ErrorCode.VALIDATION_ERROR,
+        'Invalid workspace slug. Must be 4-50 chars matching [a-zA-Z0-9_-].',
+        requestId,
+      );
+    }
+
+    const purge = event.queryStringParameters?.purge === 'true';
+
+    // ─── Locate the registry row by slug ─────────────────────────────
+    // The registry table is keyed on `linear_workspace_id`, so a slug
+    // lookup is a filtered scan. Only `status='active'` rows are valid
+    // removal targets — an already-revoked (or unknown) slug returns 404
+    // so the endpoint is not a revoke-oracle and we never re-run the
+    // destructive path on a row that's already been torn down.
+    //
+    // No `Limit`: DynamoDB applies a FilterExpression *after* evaluating
+    // items, so `Limit: N` bounds items examined, not items matched — a
+    // filtered `Limit: 1` scan can return `[]` + a LastEvaluatedKey while
+    // the target sits one page deeper (the normal shared-stack state once
+    // the registry holds more than one row). We paginate to completion
+    // instead, matching the small-table convention already used for this
+    // registry in `jira-webhook-processor.ts` and `shared/linear-issue-lookup.ts`.
+    // The registry holds one row per onboarded workspace and stays small
+    // (tens of rows at most); if it ever grows large, add a GSI on
+    // `workspace_slug` and Query it.
+    let row: Record<string, unknown> | undefined;
+    let scanKey: Record<string, unknown> | undefined;
+    do {
+      const page = await ddb.send(new ScanCommand({
+        TableName: WORKSPACE_REGISTRY_TABLE,
+        FilterExpression: 'workspace_slug = :slug AND #status = :active',
+        ExpressionAttributeNames: { '#status': 'status' },
+        ExpressionAttributeValues: { ':slug': slug, ':active': 'active' },
+        ExclusiveStartKey: scanKey,
+      }));
+      row = page.Items?.[0];
+      scanKey = page.LastEvaluatedKey as Record<string, unknown> | undefined;
+    } while (!row && scanKey);
+    if (!row) {
+      // Collapse "no such row" and "already revoked" into one 404 — the
+      // caller learns nothing about existence, and there's nothing left
+      // to remove either way.
+      return errorResponse(404, ErrorCode.WORKSPACE_NOT_FOUND, `Workspace '${slug}' is not an active registration.`, requestId);
+    }
+
+    // ─── Admin authorization ─────────────────────────────────────────
+    const installedBy = row.installed_by_platform_user_id as string | undefined;
+    if (installedBy !== userId) {
+      logger.warn('Linear remove-workspace rejected: caller is not the workspace admin', {
+        request_id: requestId,
+        workspace_slug: slug,
+      });
+      return errorResponse(403, ErrorCode.FORBIDDEN, 'Only the workspace admin who installed this workspace may remove it.', requestId);
+    }
+
+    const linearWorkspaceId = row.linear_workspace_id as string;
+    const oauthSecretArn = row.oauth_secret_arn as string | undefined;
+    const now = new Date().toISOString();
+
+    // Track which teardown phase we're in so a mid-stream failure logs
+    // *where* it broke — critical because the registry row is revoked
+    // first (fail-closed), so a later failure can leave a live OAuth
+    // secret orphaned. On-call needs the phase + workspace id from the
+    // error log to find and hand-purge it.
+    phase = 'registry_write';
+
+    // ─── Registry: revoke first (fail-closed), always ────────────────
+    // Even on `--purge` we flip the row to `status='revoked'` BEFORE
+    // deleting the secret, rather than deleting the row outright. This is
+    // deliberate: the OAuth resolver fail-closes on any non-active status,
+    // so the workspace stops resolving tokens and routing webhooks the
+    // instant this write lands. It also keeps the row present through the
+    // secret-delete step, so a failure there can persist a durable
+    // orphaned-secret marker on the row (see `markSecretDeletionFailed`).
+    // The hard `--purge` delete of the row happens only AFTER the secret
+    // is confirmed gone.
+    await ddb.send(new UpdateCommand({
+      TableName: WORKSPACE_REGISTRY_TABLE,
+      Key: { linear_workspace_id: linearWorkspaceId },
+      UpdateExpression: 'SET #status = :revoked, revoked_at = :now, revoked_by_platform_user_id = :uid, updated_at = :now',
+      ExpressionAttributeNames: { '#status': 'status' },
+      ExpressionAttributeValues: { ':revoked': 'revoked', ':now': now, ':uid': userId },
+    }));
+
+    // ─── Secrets Manager: delete the per-workspace OAuth secret ───────
+    // Idempotent: a ResourceNotFoundException means the secret was already
+    // removed by a prior (partial) run — that's success, not an error.
+    phase = 'secret_delete';
+    let secretDeleted = false;
+    if (oauthSecretArn) {
+      try {
+        await sm.send(new DeleteSecretCommand({
+          SecretId: oauthSecretArn,
+          // No recovery window — the workspace is being torn down and the
+          // registry row is the audit record. Leaving a scheduled-deletion
+          // secret around would block a same-slug re-onboarding.
+          ForceDeleteWithoutRecovery: true,
+        }));
+        secretDeleted = true;
+      } catch (err) {
+        const name = (err as { name?: string }).name;
+        if (name !== 'ResourceNotFoundException') {
+          // A real SM failure (e.g. AccessDenied, throttle). The registry
+          // row is already revoked (fail-closed holds) AND still present
+          // (the `--purge` delete has not run yet), so we persist a durable
+          // marker on the row (best-effort) so the leaked secret is
+          // discoverable and the operator can hand-purge it, then surface a
+          // distinct, actionable error instead of an opaque 500. We do NOT
+          // proceed to the `--purge` row delete — deleting the row here
+          // would strip the only durable record of the orphaned secret. Do
+          // NOT swallow.
+          await markSecretDeletionFailed(linearWorkspaceId, oauthSecretArn, name)
+            .catch((markErr) => logger.error('Failed to persist secret-deletion-failed marker', {
+              request_id: requestId,
+              linear_workspace_id: linearWorkspaceId,
+              error: markErr instanceof Error ? markErr.message : String(markErr),
+            }));
+          logger.error('Linear OAuth secret delete failed — workspace revoked but secret must be manually purged', {
+            request_id: requestId,
+            workspace_slug: slug,
+            linear_workspace_id: linearWorkspaceId,
+            oauth_secret_arn: oauthSecretArn,
+            error_name: name,
+          });
+          return errorResponse(
+            500,
+            ErrorCode.SECRET_DELETE_FAILED,
+            `Workspace '${slug}' was revoked but its OAuth secret could not be deleted. `
+            + 'The workspace is disabled (fail-closed), but an operator must manually delete '
+            + `the Secrets Manager secret. Request ID ${requestId}.`,
+            requestId,
+          );
+        }
+        logger.info('Linear OAuth secret already absent — treating removal as idempotent', {
+          request_id: requestId,
+          workspace_slug: slug,
+        });
+      }
+    }
+
+    // ─── Registry: purge (hard delete) ───────────────────────────────
+    // Only on `--purge`, and only now that the secret is confirmed gone —
+    // so we never delete the audit/marker row while a live secret could
+    // still be orphaned.
+    if (purge) {
+      phase = 'registry_write';
+      await ddb.send(new DeleteCommand({
+        TableName: WORKSPACE_REGISTRY_TABLE,
+        Key: { linear_workspace_id: linearWorkspaceId },
+      }));
+    }
+
+    logger.info('Linear workspace removed', {
+      request_id: requestId,
+      workspace_slug: slug,
+      linear_workspace_id: linearWorkspaceId,
+      mode: purge ? 'purged' : 'revoked',
+      secret_deleted: secretDeleted,
+    });
+
+    return successResponse(200, {
+      workspace_slug: slug,
+      linear_workspace_id: linearWorkspaceId,
+      status: purge ? 'purged' : 'revoked',
+      secret_deleted: secretDeleted,
+    }, requestId);
+  } catch (err) {
+    // Include the workspace slug + failing phase so on-call can locate an
+    // orphaned secret / half-cleaned mapping table from the error log.
+    logger.error('Linear remove-workspace handler failed', {
+      error: err instanceof Error ? err.message : String(err),
+      request_id: requestId,
+      workspace_slug: slug,
+      phase,
+    });
+    return errorResponse(500, ErrorCode.INTERNAL_ERROR, 'Internal server error.', requestId);
+  }
+}
+
+/**
+ * Best-effort durable marker written to the registry row when the OAuth
+ * secret delete fails after the row was already revoked. The registry row is
+ * always still present at this point — the revoke is an `UpdateCommand` and
+ * the `--purge` row delete runs only after the secret is confirmed gone — so
+ * the marker survives on every flag combination and makes the orphaned-secret
+ * condition discoverable. Never throws to the caller — the caller already
+ * logs + returns an actionable error.
+ */
+async function markSecretDeletionFailed(
+  linearWorkspaceId: string,
+  oauthSecretArn: string,
+  errorName: string | undefined,
+): Promise<void> {
+  await ddb.send(new UpdateCommand({
+    TableName: WORKSPACE_REGISTRY_TABLE,
+    Key: { linear_workspace_id: linearWorkspaceId },
+    UpdateExpression:
+      'SET secret_deletion_failed = :t, secret_deletion_error = :e, orphaned_oauth_secret_arn = :arn',
+    ExpressionAttributeValues: {
+      ':t': true,
+      ':e': errorName ?? 'unknown',
+      ':arn': oauthSecretArn,
+    },
+  }));
+}

cdk/src/handlers/shared/response.ts

@@ -35,6 +35,8 @@ export const ErrorCode = {
   WEBHOOK_ALREADY_REVOKED: 'WEBHOOK_ALREADY_REVOKED',
   API_KEY_NOT_FOUND: 'API_KEY_NOT_FOUND',
   API_KEY_ALREADY_REVOKED: 'API_KEY_ALREADY_REVOKED',
+  WORKSPACE_NOT_FOUND: 'WORKSPACE_NOT_FOUND',
+  SECRET_DELETE_FAILED: 'SECRET_DELETE_FAILED',
   REPO_NOT_ONBOARDED: 'REPO_NOT_ONBOARDED',
   SERVICE_UNAVAILABLE: 'SERVICE_UNAVAILABLE',
   INTERNAL_ERROR: 'INTERNAL_ERROR',