feat: upgrade Backstage from 1.51.1 to 1.53.1

[johnnyhuy]

Summary

• Bumped `backstage.json` and the yarn backstage plugin spec from 1.51.1 to 1.53.1 (latest stable, released 2026-07-29)
• Yarn install pulled in updated `@backstage/*` packages (e.g. `cli` 0.36.2 → 0.36.4, `plugin-catalog` 2.0.5 → 2.0.7, `plugin-scaffolder` 1.37.0 → 1.38.1, `plugin-auth-backend` 0.29.0 → 0.29.2, `frontend-plugin-api` 0.17.1 → 0.17.3, `ui` 0.15.0 → 0.17.0, `backend-defaults` 0.17.2 → 0.17.6, `plugin-notifications` 0.5.17 → 0.5.19, `plugin-signals` 0.0.31 → 0.0.33)

Consequences

None for this codebase. Notable v1.52 / v1.53 breaking changes were checked against current code and `app-config.yaml`:

• `discovery.endpoints` object form — not configured
• `ComboboxProps` / `SelectProps` union types — not extended
• `PolicyQueryUser.token` / `expiresInSeconds` removal — module already uses `info`
• `catalog.stitchingStrategy.mode: 'immediate'` removal — not configured
• Default Kubernetes `/kubernetes` page removal — not used
• MS Graph disabled user filtering — not used
• MCP SSE transport removal — not used
• `bootstrapEnvProxyAgents` removal — not used

The 1.53.1 `legacy-app` template additionally adds `@backstage/plugin-user-settings-backend`, which is optional (database-backed user settings — we use browser local storage via the frontend `plugin-user-settings`).

Testing

Local verification on macOS (mise-managed toolchain, Node 22.11.0, Yarn 4.3.1):

• `yarn lint:all` — passes across all 5 packages
• `yarn test --watchAll=false` — 9 tests pass, 1 skipped (pre-existing `App.test.tsx`)
• `yarn build:all` — frontend (Rspack) and backend bundles build clean
• `yarn dev` (full stack) — backend initialises all 10 plugins (`app`, `auth`, `catalog`, `notifications`, `permission`, `proxy`, `scaffolder`, `search`, `signals`, `techdocs`), guest auth issues tokens, catalog returns 73 entities across 7 kinds, frontend compiles and serves on `:3000`

CI will pick this up via the existing `build.yml` workflow.

Note: prior PR #94 on the original `chore/upgrade-backstage-1.53.1` branch was closed because that branch was 11 commits behind main and carried redundant padding-fix commits that conflicted. This single-commit PR is rebased cleanly on top of `main`.

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	@​backstage/​plugin-permission-backend-module-allow-all-policy@​0.2.19 ⏵ 0.2.21
	@​backstage/​plugin-catalog-backend-module-scaffolder-entity-model@​0.2.20 ⏵ 0.2.22
	@​backstage/​plugin-permission-react@​0.5.1 ⏵ 0.5.3
	@​backstage/​cli-defaults@​0.1.2 ⏵ 0.1.4				+1
	@​backstage/​plugin-permission-backend@​0.7.12 ⏵ 0.7.14
	@​backstage/​plugin-scaffolder-backend-module-notifications@​0.1.22 ⏵ 0.1.24
	@​backstage/​plugin-techdocs-module-addons-contrib@​1.1.36 ⏵ 1.1.38	+1		+1
	@​backstage/​plugin-signals-backend@​0.3.15 ⏵ 0.3.17
	@​backstage/​plugin-auth-backend-module-gitlab-provider@​0.4.3 ⏵ 0.4.5	+1		+1
	@​backstage/​plugin-auth-backend-module-github-provider@​0.5.3 ⏵ 0.5.5	+1		+1
	@​backstage/​integration-react@​1.2.18 ⏵ 1.2.20
	@​backstage/​plugin-permission-node@​0.11.0 ⏵ 0.11.2
	@​backstage/​plugin-auth-node@​0.7.1 ⏵ 0.7.3
	@​backstage/​plugin-search-react@​1.11.4 ⏵ 1.11.6
	@​backstage/​plugin-techdocs-react@​1.3.11 ⏵ 1.3.13	+1		+1
	@​backstage/​plugin-scaffolder-common@​2.2.0 ⏵ 2.2.1				-1
	@​backstage/​plugin-search-backend@​2.1.2 ⏵ 2.1.4
	@​backstage/​plugin-scaffolder-backend-module-github@​0.9.9 ⏵ 0.9.11			+1
	@​backstage/​app-defaults@​1.7.8 ⏵ 1.7.10	+1		+1
	@​backstage/​plugin-scaffolder-backend@​4.0.0 ⏵ 4.0.2	+1
	@​backstage/​plugin-notifications@​0.5.17 ⏵ 0.5.19	+1
	@​backstage/​dev-utils@​1.1.23 ⏵ 1.1.25
	@​backstage/​frontend-plugin-api@​0.17.1 ⏵ 0.17.3			+1
	@​backstage/​plugin-signals@​0.0.31 ⏵ 0.0.33
	@​backstage/​core-plugin-api@​1.12.6 ⏵ 1.12.8
	@​backstage/​ui@​0.15.0 ⏵ 0.17.0
	@​backstage/​test-utils@​1.7.18 ⏵ 1.7.20
	@​backstage/​plugin-search-backend-module-techdocs@​0.4.14 ⏵ 0.4.16	+1		+1
	@​backstage/​plugin-techdocs@​1.17.6 ⏵ 1.17.8	+1		+1
	@​backstage/​backend-plugin-api@​1.9.1 ⏵ 1.9.3	+1		+1
	@​backstage/​plugin-search-backend-node@​1.4.4 ⏵ 1.4.6
	@​backstage/​plugin-catalog-react@​3.0.0 ⏵ 3.2.0			+1
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[socket-security]

Warning

Review the following alerts detected in dependencies.

According to your organization's Security Policy, it is recommended to resolve "Warn" alerts. Learn more about Socket for GitHub.

Action	Severity	Alert  (click "▶" to expand/collapse)
Warn		Obfuscated code: npm underscore is 90.0% likely obfuscated Confidence: 0.90 Location: Package overview From: ? → npm/@backstage/backend-defaults@0.17.6 → npm/underscore@1.13.8 ℹ Read more on: This package | This alert | What is obfuscated code? Next steps: Take a moment to review the security alert above. Review the linked package source code to understand the potential risk. Ensure the package is not malicious before proceeding. If you're unsure how to proceed, reach out to your security team or ask the Socket team for help at support@socket.dev. Suggestion: Packages should not obfuscate their code. Consider not using packages with obfuscated code. Mark the package as acceptable risk. To ignore this alert only in this pull request, reply with the comment @SocketSecurity ignore npm/underscore@1.13.8. You can also ignore all packages with @SocketSecurity ignore-all. To ignore an alert for all future pull requests, use Socket's Dashboard to change the triage state of this alert.

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