# Task 5 report — backend principal enforcement

## RED

Added backend route/auth tests before implementation. The initial focused run failed in
seven new assertions: `getPrincipal` did not exist, upstream requests still required the
legacy identity header, foreign session/SSE routes were not hidden, admin scope was not
enforced, new sessions had no trusted principal binding, and settings were global.

## GREEN

- Focused backend suite: `66 passed` across auth, sessions, SSE, and settings tests.
- Complete backend Vitest suite: `209 passed` across `22` files.
- `npx tsc --noEmit -p .`, `npm run build`, `git diff --check`, and changed Python
  source Ruff all exit successfully.
- Harness targeted repository/local/migration tests and Python bytecode compilation exit
  successfully. The new `tht session preferences get|set` commands are registered and
  expose the expected Typer help. A direct local CLI preference smoke was not run because
  the checked-in local workspace requires unavailable `THT_DB_HOST` configuration.

## Route and child-process coverage

- `GET /me` returns the request `PrincipalContext`; upstream accepts only the portal's
  normalized `X-Thoth-*` identity tuple, with the legacy header ignored. Local mode uses
  the same stable `THT_HOME`/`~/.thothii/identity.json` UUID contract as the harness.
- All session operations are principal-scoped: list (`mine` and admin-only `all`), show,
  create, resume, close, delete, rename, group, archive, unarchive, documents, reviewer
  response, steer, SQL preview/export, and SSE. Missing and foreign sessions are 404;
  absent upstream identity is 401. SSE is authorized before response headers or hub
  subscription, so a rejected request cannot attach to a live stream.
- New/resumed Pi runtimes and every route-spawned `tht` process receive
  `THT_PRINCIPAL_ISSUER`, `THT_PRINCIPAL_SUBJECT`, optional display name, and admin flag.
  The readiness `tht` child is also principal-bound.
- Settings use asynchronous repository-backed `tht session preferences get|set` in the
  production runner, which isolates preferences by principal. The legacy settings file is
  retained only as an injected-runner compatibility fallback for existing isolated tests.
- Repository/settings authorization failures map to 503 before model startup. SQL execution
  errors remain 500 after authorization, preserving the prior API distinction.

## Self-review and concerns

- Confirmed the Task 4 portal emits lowercase `true`/`false` for the admin header; the
  parser accepts that exact normalized form plus the repository's existing `1`/`0`
  compatibility form, and rejects all other values.
- The harness principal resolver is the ownership authority; the backend never accepts an
  owner supplied in request bodies. Its route guards use a repository-scoped `session show`
  before every session resource operation.
- Existing dependency-injected route fakes without `sessionShow` retain a narrow test seam;
  production `ThtRunner` always has that method, so deployed requests cannot bypass the
  repository authorization check.

## Review follow-up

### RED

Focused regressions initially failed exactly at the three review findings: stale ambient
display names survived into both `tht` and Pi child environments; mutation/document runner
methods dropped the selected workspace; and `expandLocalHome` did not exist.

### GREEN

- Child environments now remove all four `THT_PRINCIPAL_*` keys from their cloned base
  environment before applying the exact request principal. Regression tests prove an absent
  display name does not inherit a stale ambient value in either child path.
- `setName`, `setGroup`, `archive`, `unarchive`, and `documents` now take and retain an
  optional workspace. The rename route regression proves `session show` authorization and
  the mutation use the same non-default workspace.
- Local principal paths expand `~`/`~/...`; existing local home and identity file modes are
  repaired to POSIX `0700`/`0600` when applicable, with Windows left unchanged.
- Focused suite: `74 passed`; full backend suite: `213 passed` across `22` files, followed by
  TypeScript typecheck, production build, and diff check.