feat(fleet): add reviewed v1-to-v2 migration preview

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/mosaic/src/commands/fleet-migration-command.ts

@@ -0,0 +1,153 @@
+import { readFile } from 'node:fs/promises';
+import { join } from 'node:path';
+import type { Command } from 'commander';
+import {
+  parseV1MigrationObservations,
+  parseV1ToV2MigrationDecisions,
+  previewV1ToV2Migration,
+} from '../fleet/v1-v2-migration.js';
+
+export interface FleetMigrationCommandDeps {
+  readonly mosaicHome?: string;
+  readonly rolesDir?: string;
+  readonly overrideDir?: string;
+  readonly readText?: (path: string) => Promise<string>;
+  readonly printJson?: (value: unknown) => void;
+  readonly setExitCode?: (code: number) => void;
+}
+
+interface PreviewOptions {
+  readonly source?: string;
+  readonly decisions?: string;
+  readonly observations?: string;
+}
+
+/** Registers preview-only v1 migration. This command has no mutation verbs or runners. */
+export function registerFleetMigrationCommand(
+  fleetCommand: Command,
+  deps: FleetMigrationCommandDeps = {},
+): void {
+  fleetCommand
+    .command('migrate-v1')
+    .description('Preview a field-complete v1-to-v2 roster migration')
+    .command('preview')
+    .description('Compile migration evidence without writing files or changing runtimes')
+    .option('--source <path>', 'v1 roster YAML or JSON')
+    .option('--decisions <path>', 'explicit migration decisions JSON')
+    .option('--observations <path>', 'reviewed lifecycle observations JSON')
+    .action(async (options: PreviewOptions): Promise<void> => {
+      const readText = deps.readText ?? ((path: string): Promise<string> => readFile(path, 'utf8'));
+      const printJson =
+        deps.printJson ?? ((value: unknown): void => console.log(JSON.stringify(value)));
+      const setExitCode =
+        deps.setExitCode ?? ((code: number): void => void (process.exitCode = code));
+      try {
+        const requiredOptionNames = ['source', 'decisions', 'observations'] as const;
+        const missingOption = requiredOptionNames.find((name) => options[name] === undefined);
+        if (missingOption !== undefined) {
+          printJson({
+            status: 'blocked',
+            blockers: [
+              {
+                code: 'missing-migration-preview-option',
+                path: `request.${missingOption}`,
+                detail: 'Required migration preview option is missing.',
+              },
+            ],
+          });
+          setExitCode(1);
+          return;
+        }
+        const emptyOption = requiredOptionNames.find((name) => options[name]?.trim() === '');
+        if (emptyOption !== undefined) {
+          printJson({
+            status: 'blocked',
+            blockers: [
+              {
+                code: 'empty-migration-preview-option',
+                path: `request.${emptyOption}`,
+                detail: 'Required migration preview option must be a non-empty path.',
+              },
+            ],
+          });
+          setExitCode(1);
+          return;
+        }
+        const sourcePath = options.source;
+        const decisionsPath = options.decisions;
+        const observationsPath = options.observations;
+        if (
+          sourcePath === undefined ||
+          decisionsPath === undefined ||
+          observationsPath === undefined
+        ) {
+          throw new Error('Validated migration preview options became unavailable.');
+        }
+        const [source, decisionsSource, observationsSource] = await Promise.all([
+          readText(sourcePath),
+          readText(decisionsPath),
+          readText(observationsPath),
+        ]);
+        const decisions = parseV1ToV2MigrationDecisions(
+          parseJsonObject(decisionsSource, 'migration decisions'),
+        );
+        const observations = parseV1MigrationObservations(
+          parseJsonObject(observationsSource, 'lifecycle observations'),
+        );
+        const mosaicHome =
+          deps.mosaicHome ?? fleetCommand.opts<{ mosaicHome: string }>().mosaicHome;
+        const preview = await previewV1ToV2Migration({
+          source,
+          sourcePath,
+          decisions,
+          observations,
+          personaDirs: {
+            rolesDir: deps.rolesDir ?? join(mosaicHome, 'fleet', 'roles'),
+            overrideDir: deps.overrideDir ?? join(mosaicHome, 'fleet', 'roles.local'),
+          },
+          environment: {
+            mosaicHome,
+            agentEnvDir: join(mosaicHome, 'fleet', 'agents'),
+          },
+        });
+        printJson(preview);
+        if (preview.status === 'blocked') setExitCode(1);
+      } catch (error: unknown) {
+        printJson({
+          status: 'blocked',
+          blockers: [
+            {
+              code: 'migration-preview-failed',
+              path: 'request',
+              detail: safeErrorDetail(error),
+            },
+          ],
+        });
+        setExitCode(1);
+      }
+    });
+}
+
+function parseJsonObject(source: string, label: string): unknown {
+  let value: unknown;
+  try {
+    value = JSON.parse(source) as unknown;
+  } catch {
+    throw new Error(`${label} must be valid JSON.`);
+  }
+  if (typeof value !== 'object' || value === null || Array.isArray(value)) {
+    throw new Error(`${label} must be a JSON object.`);
+  }
+  return value;
+}
+
+function safeErrorDetail(error: unknown): string {
+  if (error instanceof Error && isPublishableValidationMessage(error.message)) return error.message;
+  return 'Migration preview failed without publishable detail.';
+}
+
+function isPublishableValidationMessage(message: string): boolean {
+  return /^(migration decisions|lifecycle observations) must be (valid JSON|a JSON object)\.$/.test(
+    message,
+  );
+}