docs: reflect shipped Docker session mode (1.4.0) across CLAUDE.md/README/security

- CLAUDE.md: rewrite the Docker cases Key Pattern to the shipped 1.4.0 state
  (removes the stale "not on master / Phases remaining" framing); add
  docker-quickcreate/templates/GPU/elastic-disk/export-import, the
  CODEMAN_DOCKER_BRIDGE_HOOKS listener, docker state files, env vars, route +
  SSE counts, and the build-agent-image command.
- README.md: new "Isolated Docker Sessions" section + a More Features bullet.
- docs/security-architecture.md: new §10 "Docker container isolation" (hardening,
  commit-safe creds, blast radius, untrusted-import safety, bridge-hooks) +
  Quick-reference env vars.

docs/docker-cases.md (user guide) and docs/docker-cases-plan.md (design) were
shipped with the feature.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/security-architecture.md

@@ -30,7 +30,8 @@ an explicit, guided opt‑in.
 7. [Supply‑chain & build‑asset hardening](#7-supplychain--buildasset-hardening-cod28)
 8. [Multi‑instance isolation](#8-multiinstance-isolation)
 9. [Transport security headers](#9-transport-security-headers)
-10. [Quick reference](#10-quick-reference)
+10. [Docker container isolation](#10-docker-container-isolation)
+11. [Quick reference](#11-quick-reference)
 
 ---
 
@@ -471,7 +472,22 @@ production layout (`~/.codeman`, `-L codeman`, port 3000).
 
 ---
 
-## 10. Quick reference
+## 10. Docker container isolation
+
+Docker cases (1.4.0) run a session inside a per‑case container instead of on the host. The security posture:
+
+- **Hardened create flags, always** — `--cap-drop ALL`, `--security-opt no-new-privileges`, `--pids-limit` (fork‑bomb guard), `--memory` == `--memory-swap` (a real OOM cap), `--init`, and non‑root: `--user <hostUid>:0` on Linux (host uid → workspace files stay host‑owned; GID 0 keeps `$HOME` writable), `--userns=keep-id` on rootless Podman. **Never** `--privileged`, and **never** the docker socket — the pure builder in `docker-hosts.ts` cannot emit them and the schema cannot represent them.
+- **Credentials never enter an image** — the convenient default bind‑mounts host cred dirs (`~/.claude`, `~/.codex`, `~/.gemini`, `~/.config/{gcloud,opencode}`) read‑write. Bind mounts are physically excluded from `docker commit`, so exported images are secret‑free. API‑key CLIs get their key as an exec‑time NAME‑ONLY `--env OPENAI_API_KEY` (no `=value`, no `ps` leak, never committed); a create‑time `-e` for a secret is never used. The **sealed** profile (`mountCredentials:false` + `network:none`) drops the host mounts; full‑image export is then refused (an in‑container login would ride the committed layer) unless a pre‑commit scrub is opted into.
+- **Blast radius — accept it explicitly** — the convenient profile mounts an arbitrary host workspace RW plus the host credential dirs RW into a network‑enabled container, so container‑run agent code can read/modify those host trees and reach the network at once. Still a net improvement over today's on‑host `--dangerously-skip-permissions` execution; use the sealed profile for genuinely untrusted work.
+- **Import is untrusted‑bundle‑safe** — `/api/docker-cases/import` validates the manifest + per‑member SHA‑256 before extraction, rejects absolute / `..` tar members (traversal guard), and re‑tags the loaded image into a quarantined namespace so it can never overwrite `codeman/agent:base` or a pre‑existing tag.
+- **Host guard & the bridge‑hooks listener** — in‑container hook callbacks carry `Host: host.docker.internal` / `host.containers.internal`; both are on the always‑on host‑header allowlist (`DOCKER_HOST_GATEWAY_ALIASES`) and resolve to the host only from inside a container netns, so they are not a browser DNS‑rebinding surface. On a loopback‑only server, in‑container hooks are opt‑in via `CODEMAN_DOCKER_BRIDGE_HOOKS=1`, which binds a SECOND listener on the docker bridge gateway serving **only** the hook endpoints (every other path → `403`) into the same hook‑secret‑gated pipeline. The bridge is host‑internal (containers + host), not the LAN, so it does not widen network exposure; the hook secret is bind‑mounted read‑only and referenced by path.
+- **Instance isolation** — every managed container is labeled `codeman.instance=<CODEMAN_INSTANCE>`; the boot reaper reaps orphans of its OWN instance only, so a beta never removes a prod container. The in‑container tmux socket (`-L codeman-docker`) + session name (`codeman-dkr-*`) deliberately fail a nested Codeman's discovery pattern.
+
+Full feature guide: [`docker-cases.md`](docker-cases.md).
+
+---
+
+## 11. Quick reference
 
 | Env / flag | Effect |
 |------------|--------|
@@ -482,6 +498,8 @@ production layout (`~/.codeman`, `-L codeman`, port 3000).
 | `--https` | Enable TLS (adds HSTS) |
 | `CODEMAN_INSTANCE` | Scope tmux socket + data dir for isolation |
 | `CODEMAN_GESTURE=1` | Make the gesture overlay available (widens CSP) |
+| `CODEMAN_DOCKER_BRIDGE_HOOKS=1` | Serve the hook endpoints on the docker bridge gateway (host‑internal, hooks‑only, `403` elsewhere) so in‑container hooks reach a loopback‑bound server — see §10 |
+| `CODEMAN_DOCKER_BRIDGE_HOST` | Override the bridge gateway IP the hooks listener binds (default: auto‑detect) |
 
 **Audit log:** session lifecycle and server start are recorded in
 `~/.codeman/session-lifecycle.jsonl`.