feat: embedder environment-hint hook for the system prompt (#34574)

* fix(security): block AWS SDK creds from subprocess env

* fix(security): narrow Bedrock subprocess strip to inference bearer token only

Scopes the AWS_SDK subprocess strip down from the full AWS credential chain
to just AWS_BEARER_TOKEN_BEDROCK — the only Hermes-managed *inference* secret
(analogous to OPENAI_API_KEY). The general AWS credential chain
(AWS_ACCESS_KEY_ID / AWS_SECRET_ACCESS_KEY / AWS_SESSION_TOKEN / AWS_PROFILE
/ config + role pointers) is intentionally left inheritable.

Why: per SECURITY.md §3.2 the local terminal is the user's trusted operator
shell. Hard-blocklisting the general chain would (a) regress *every* user who
runs aws/terraform/cdk/boto3 in the agent terminal — not just Bedrock users,
since PROVIDER_REGISTRY is iterated unconditionally at import — and (b) be
unrecoverable, because env_passthrough.py refuses to re-allow anything in
_HERMES_PROVIDER_ENV_BLOCKLIST (GHSA-rhgp-j443-p4rf). The narrow strip closes
the reported leak (opencode enumerating the Bedrock catalog off the leaked
bearer token) with no capability loss.

Keeps zapabob's self-healing auth_type=="aws_sdk" mechanism so any future
SDK-cred provider is covered automatically.

Tests: bearer token stripped + general chain preserved (no-regression guard),
on both the runtime strip path and the blocklist-membership path.

Co-authored-by: zapabob <1920071390@campus.ouj.ac.jp>

* feat: embedder environment-hint hook for the system prompt

Adds HERMES_ENVIRONMENT_HINT env var (and config.yaml agent.environment_hint)
so a host wrapping Hermes (sandbox runner, managed platform) can describe the
runtime environment — proxy, credential handling, mount layout — in the system
prompt's environment-hints block, without editing the identity slot (SOUL.md).

Read once at prompt-build time, so it lands in the stable, cache-safe portion
of the system prompt. Env var overrides the config key (build-time/container
mechanism). Empty by default — no behavior change for existing installs.

---------

Co-authored-by: zapabob <1920071390@campus.ouj.ac.jp>

agent/prompt_builder.py

@@ -848,6 +848,27 @@ def build_environment_hints() -> str:
 
     if is_wsl():
         hints.append(WSL_ENVIRONMENT_HINT)
+
+    # Embedder-supplied environment description. Lets a host that wraps Hermes
+    # (e.g. a sandbox runner / managed platform) explain the environment the
+    # agent is running in — proxy, credential handling, mount layout — without
+    # forking the identity slot (SOUL.md). Read once at prompt-build time, so
+    # it's part of the stable, cache-safe system prompt. The env var is the
+    # build-time/embedder mechanism (set in a container ENV); config.yaml
+    # ``agent.environment_hint`` is the user-facing surface. Env var wins.
+    extra = (os.getenv("HERMES_ENVIRONMENT_HINT") or "").strip()
+    if not extra:
+        try:
+            from hermes_cli.config import load_config
+
+            extra = str(
+                (load_config().get("agent", {}) or {}).get("environment_hint", "")
+            ).strip()
+        except Exception as e:
+            logger.debug("Could not read agent.environment_hint from config: %s", e)
+    if extra:
+        hints.append(extra)
+
     return "\n\n".join(hints)