Bind credential exec to exact owner inputs and approval digest

Assistant: codex
Assistant-Model: gpt-6-astra
Assistant-Session: 01a07ff8-19d0-7820-b4d0-1353833cb7fc

docs/exec-owner-binding.md

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+# Bind native exec delivery to its reviewed recipient
+
+SECRETS-WP-0009-T03. Implemented 2026-09-10. This constrains delivery; it is not
+an approval or proof of native credential access.
+
+Previously `exec` consumed approval for a catalog/action/field, then accepted an
+arbitrary child command and copied the invoking engine's full environment. The
+factory recipient is now a pinned metered owner outside the sandbox. A different
+command or inherited engine credential would violate that boundary.
+
+Catalog `delivery_config.exec_owner` is optional for existing lanes. The Claude
+factory lane explicitly requires it and currently declares `status: pending`,
+`owner` and `reason`. Pending means no exec: refusal precedes approval consumption,
+backend opening and secret retrieval. Routing stays unready even if custody exists.
+
+A reviewed binding uses exactly these keys:
+
+| Key | Required content |
+| --- | --- |
+| `status` | `configured`; this describes configuration, not authorization |
+| `owner` | Named trusted recipient |
+| `command` | Exact argv; absolute executable, no caller-selected additional arguments |
+| `cwd` | Exact private owner directory |
+| `environment` | Complete non-secret environment; no inheritance from the engine |
+| `files` | Absolute path → `{sha256: <64 lowercase hex>, private: <boolean>}` |
+
+The executable and every absolute file argument require pins. Include the exact
+owner JSON and all immutable files it references, such as the spend-policy and
+accepted profile/descriptor configuration. Mutable ledgers are private state,
+not immutable file pins. The runtime owner retains whole-artifact and operational
+profile verification; hashing an interpreter alone does not verify its packages.
+
+File checks refuse symlinks, nonregular inputs, untrusted owners, group/world
+writable paths and ancestors, changed bytes and exposed private inputs. Root-owned
+sticky temporary ancestors are allowed for contained proof. The working directory
+is private. The engine and configured owner UID remain trusted: this does not
+protect against that same trusted UID replacing files between checks and launch.
+Runtime and native service admission must preserve this trust boundary.
+
+Only exec-env is allowed with this binding. The child receives the fixed environment
+plus the selected declared field; loader overrides and engine/provider auth
+variables cannot be supplied as fixed environment configuration. No values belong
+in the catalog. Queue/service credentials, if needed by the owner, require their
+separate admitted custody path. Child stdin is closed; stdout/stderr retain the
+existing value redactor. An arbitrary encoding by a malicious recipient is not
+made safe by redaction; the recipient itself must be trusted and admitted.
+
+SHA-256 of the complete canonical binding is carried as
+`context.exec_owner_sha256` on the `exec` CheckRequest. The existing producer digest
+and approval join bind it without introducing another decision type. Changing
+command, file pins, environment, cwd or owner changes the request and requires new
+exact-action approval. Local checks run before approval/backend, again before
+retrieval, and after retrieval before launch; the admitted digest must still match.
+Configured bindings still pass existing approval, consume, lane-state and scoped
+backend checks. Other actions and lanes without this opt-in retain their contracts.
+
+## Factory activation input
+
+Use the installed artifact and paths in
+`prj-helixforge-factory/evidence/2026-09-10-runtime-placement.json`. The intended argv:
+
+```text
+<protected-runtime>/bin/python3 -I -B -m rein_aharness.cli metered-once --owner-config <private-owner-config>
+```
+
+Do not use the rolling CLI alias or a persistent claim loop. Complete and pin the
+private owner configuration, profile and spend inputs under HFACT-WP-0001-T01/T04;
+bind the required worker environment explicitly. Then review the MessagesOwner
+holder under this task and the existing native action/reader gates. The provider
+key stays in the metered owner; the workload receives the opaque local route token.
+The historical sandbox-helper child-key route is not this holder admission.
+
+## Verification
+
+The full suite passed 361 tests, including a real child with a synthetic key,
+fixed environment, closed stdin, redaction and substituted/config-changed refusal.
+The disposable integration exercise passed 18 checks using the pinned KeyCape
+image, actual Approval Engine and compiled Flex Auth, including five new owner
+checks: substituted argv refusal before consume/backend, changed-environment
+replay refusal, consume-before-backend, isolated child environment and preserved
+recipient digest. OpenBao and recipient are fixtures in this exercise. The
+historical combined operator identity is a synthetic test issuer fixture, not a
+request to restore CCR-2026-0020 or evidence of real human approval.
+
+```bash
+uv run --extra dev --with 'PyJWT[crypto]>=2.7,<3' python tools/exercise_approval_identity.py \
+  --keycape-source ../key-cape --approval-engine-source ../approval-engine \
+  --flex-auth-source ../flex-auth --exec-owner --receipt /tmp/<new-receipt>.json
+```
+
+Receipt: `docs/evidence/2026-09-10-exec-owner-approval-exercise.json`.
+Native custody, exact operator group/file delivery, real human/audit/service path,
+accepted factory configuration and paid execution remain open.