{"task_id":"st_01a04d8c","status":"completed","residency_state":"persisted_only","parent_session_id":"01a04ad7-eaa9-790c-83f7-57410e6370d1","root_session_id":"01a04ad7-eaa9-790c-83f7-57410e6370d1","depth":1,"execution_mode":"in-process","model":"openai-codex/gpt-5.6-sol","notify_on_terminal":true,"created_at":"2026-08-29T12:44:19.529Z","updated_at":"2026-08-29T15:18:51.149Z","notification":{"run_epoch":0,"notified_epoch":0},"name":"authority-transition-design","task_summary":"Design append-only authority promotion rollback","description":"authority-transition-design","category":"architect","requested_model":{"provider":"openai-codex","model_id":"gpt-5.6-sol","display":"openai-codex/gpt-5.6-sol","source":"category","variant":"xhigh","reasoning_effort":"xhigh"},"fallback_models":[{"provider":"clinepass","model_id":"cline-pass/glm-5.2","display":"clinepass/cline-pass/glm-5.2","source":"category","variant":"xhigh","reasoning_effort":"medium"},{"provider":"openai-codex","model_id":"gpt-5.6-terra","display":"openai-codex/gpt-5.6-terra","source":"category","variant":"xhigh","reasoning_effort":"xhigh"}],"resolved_model":{"provider":"openai-codex","model_id":"gpt-5.6-sol","display":"GPT-5.6 Sol","source":"category","variant":"xhigh","reasoning_effort":"xhigh"},"spawn_spec":{"version":1,"cwd":"/home/cube/projects/richard/traning coach","prompt":"TASK: Design the minimal safe external Task26 candidate-authority promotion transaction for the next NutriCoach successor. DELIVERABLE: exact file/function changes, ordering relative to stop/install/switch/start, append-only rollback semantics, pin regeneration, and invariants. SCOPE: read-only /home/cube/projects/richard/.worktrees/nutricoach-v150-combined, especially gateway/platforms/task26_{candidate,runtime}_authority.py and scripts/nutricoach_v150_*. Do not edit or run live actions. VERIFY: ground every claim in file:line and explain how predecessor restoration remains authorized after successor failure. STOP WHEN: one decision-complete design with no unresolved rollback ambiguity is returned.\n\n<Category_Context>\nYou are a big-picture system design consultant, NOT an implementer.\n\n<Method>\n1. Survey the WHOLE architecture end to end before proposing anything: module boundaries, data flow, ownership, and the blast radius of the area in question.\n2. Produce at least TWO viable designs and state the trade-offs of each in concrete terms (coupling, testability, migration cost, failure modes).\n3. Recommend ONE of them with the reasoning that decided it, the boundaries it assumes, and the risks it carries.\n4. Demand the SIMPLEST architecture that handles the actual requirements. Reject enterprise patterns that do not pay for themselves.\n</Method>\n\n<Advisory_Mode>\nWhen the caller marks the task advisory-only, produce NO file edits: return the analysis, options, recommendation, and risks as structured text.\n</Advisory_Mode>\n</Category_Context>"},"final_response":"I read this as an advisory architecture task - I traced the authority and deployment paths and recommend a late, compensating Task26 promotion inside the existing stopped-service transaction.\n\n## Decision\n\nUse a **WAL-protected paired-chain append plus compensating predecessor qualification**.\n\nDo not retrofit the existing V14 package: it explicitly authorizes zero external events and omits authority promotion from its stage list (`scripts/prepare_nutricoach_v150_v14_preseal.py:354-368`). Build this into the next versioned preseal closure.\n\nThe transaction order is:\n\n```text\npreflight/reserve\nstop\nsnapshot/probe\ninstall/offline smoke/migrate/weekly smoke\nappend QUALIFY(successor)\nregenerate successor candidate + pin credentials\nswitch unit/drop-in\ndaemon-reload\nstart\npost-fence including Task26 authority\ncommit\n```\n\nOn any failure after promotion:\n\n```text\nstop successor\nrepair any interrupted paired append\nappend QUALIFY(predecessor)\nregenerate predecessor candidate + pin credentials\nverify predecessor authorization\nrestore snapshots/remove successor\ndaemon-reload\nstart predecessor\nverify predecessor service and authority\nmark ROLLED_BACK\n```\n\n## Why the current code is insufficient\n\n1. The runtime accepts only the latest non-revoked candidate (`gateway/platforms/task26_runtime_authority.py:146-148`), while a qualification event makes its digest current (`gateway/platforms/task26_candidate_authority.py:140-146,211-221`). Merely restoring unit files after promoting a successor therefore does not restore predecessor authority.\n\n2. Pins bind exact source, genesis, event count, and both chain heads; a stale pin is rejected (`gateway/platforms/task26_runtime_authority.py:76-83,104-126`). The current switch rewrites the candidate credential but copies every other credential, including the old pin, unchanged (`scripts/nutricoach_v150_host_operations.py:127-142`).\n\n3. The paired append has crash windows: registry and ledger are replaced separately (`gateway/platforms/task26_candidate_authority.py:165-166`), then each is rewritten again to add source/genesis metadata (`gateway/platforms/task26_runtime_authority.py:414-424`).\n\n4. Current rollback restores files and restarts the predecessor without restoring external authority (`scripts/nutricoach_v150_sealed_controller.py:94-129`). Authority credentials are not among the snapshot paths; only config, registry, unit, and drop-in are mutable snapshots (`scripts/nutricoach_v150_sealed_target.py:133-150`).\n\n5. An active gateway is not sufficient proof of nutrition authority. Telegram catches authority startup failure and returns disconnected rather than necessarily failing the systemd process (`gateway/platforms/telegram.py:2925-2961`), while the current post-fence checks only service/runtime and file postimages (`scripts/nutricoach_v150_host_operations.py:164-188`).\n\n## Viable designs\n\n### A. WAL-protected existing chains — recommended\n\nKeep the existing registry/ledger schemas and readers. Add a durable transition intent containing exact preimages and postimages, then update both files under the existing exclusive lock. Recovery completes a partially written pair before compensating.\n\n- **Coupling:** confined to Task26 authority and the NutriCoach controller.\n- **Migration:** no authority schema migration; existing pins and snapshots remain readable.\n- **Testability:** every registry/ledger/pin write can be fault-injected deterministically.\n- **Failure mode:** a crashed writer leaves a recoverable intent; readers fail closed until recovery.\n- **Cost:** a small WAL/reconciliation state machine.\n\n### B. Immutable event-pair files\n\nStore each registry event and ledger row together in one immutable `events/<sequence>-<hash>.json` file. Derive current authority by enumerating the event directory.\n\n- **Coupling:** changes candidate verification, runtime reads, the directory watcher, final-state sealing, fixtures, and delivered bundles.\n- **Migration:** existing paired documents need a one-time import.\n- **Testability:** simpler crash model because one rename commits one event.\n- **Failure mode:** mixed old/new readers during migration.\n- **Cost:** materially larger. Final-state code currently seals the two document hashes and heads (`gateway/platforms/task26_final_state.py:1734-1743,2186-2205`).\n\nDesign B is cleaner long-term, but it does not pay for itself for one successor transaction. Choose A.\n\n## Exact changes\n\n### `gateway/platforms/task26_candidate_authority.py`\n\n1. Extract the pure logic in `append_candidate_authority()` into:\n\n```python\nprepare_candidate_authority_append(...) -> CandidateAuthorityPostimage\n```\n\nThe result contains exact previous and next registry/ledger documents and returned heads.\n\n2. Preserve existing `source_id` and `genesis_sha256` in the prepared postimages rather than dropping and re-adding them later.\n\n3. Make `_write()` perform complete writes and fsync the containing directory after replacement. It currently performs one unchecked `os.write` and no directory fsync (`gateway/platforms/task26_candidate_authority.py:45-56`).\n\n4. Keep qualification semantics unchanged. In particular, a non-revoked predecessor may be qualified again, while a revoked digest may not (`gateway/platforms/task26_candidate_authority.py:109-117`).\n\n### `gateway/platforms/task26_runtime_authority.py`\n\nAdd:\n\n```python\nbuild_authority_pin(root, verified_state) -> dict[str, object]\nreserve_external_transition(binding) -> None\npromote_external_candidate(binding, successor_pin, successor_candidate) -> dict[str, object]\nrestore_external_predecessor(binding, predecessor_pin, predecessor_candidate) -> dict[str, object]\nrelease_external_transition(binding) -> None\n```\n\nModify `append_external_authority()` to use the same implementation.\n\nProtocol:\n\n- Hold `runtime-authority.lock` exclusively, retaining the current reader/writer linearization (`gateway/platforms/task26_runtime_authority.py:394-427`).\n- Require source ID and genesis to match the sealed baseline.\n- Persist `candidate-authority/.pending-transition.json` containing canonical pre/post documents and a document digest.\n- Each live authority document must equal either the recorded preimage or postimage. Mixed pre/post is completed forward; anything else is denied.\n- Verify both chains, write credentials, then remove and directory-fsync the WAL.\n- `build_authority_pin()` derives `event_count` from the verified registry; no caller-supplied count. Existing fixture code demonstrates the required pin fields but hardcodes the count (`scripts/dualcoach_v111_disposable_fixture.py:265-279`).\n- Keep a durable external transition reservation keyed by the sealed `authority_id`; unrelated appends are denied until commit or rollback releases it.\n\nThe pin and candidate credential names remain exactly those loaded in production: `task26-authority-pin.json` and `task26-candidate-digest` (`gateway/platforms/task26_runtime_authority.py:357-390`).\n\n### `scripts/nutricoach_v150_sealed_target.py`\n\nAdd a frozen `Task26PromotionBinding` to `HostPaths` containing:\n\n```text\nauthority_root\nsource_id\ngenesis_sha256\nbaseline_registry_head_sha256\nbaseline_ledger_head_sha256\nbaseline_event_count\npredecessor_candidate_digest\npredecessor_historical_pass_digest\nsuccessor_candidate_digest\nsuccessor_historical_pass_digest\npredecessor_pin_source\npredecessor_candidate_source\nauthority_id\n```\n\nThe external root must be absolute, private, and outside profile/package/candidate/wheel/receipt roots, matching current runtime isolation checks (`gateway/platforms/task26_runtime_authority.py:84-94,372-387`).\n\n### `scripts/nutricoach_v150_concrete_host.py`\n\nExtend `live_target()` to parse the binding; it currently binds only deployment paths and wheels (`scripts/nutricoach_v150_concrete_host.py:162-210`).\n\nAdd:\n\n```python\npreflight_task26_authority()\npromote_task26_authority()\nrestore_task26_predecessor()\nverify_task26_successor_post_fence()\nverify_task26_predecessor_restored()\n```\n\nAlso include the sealed baseline and credential paths in `recovery-manifest.json`, whose purpose is fresh-process recovery (`scripts/nutricoach_v150_concrete_host.py:244-314`).\n\n`restore_task26_predecessor()` must be idempotent against three exact chain states:\n\n| Head | Action |\n|---|---|\n| Baseline `N`, predecessor current | Promotion never committed; regenerate/verify baseline predecessor credentials only. |\n| Expected `N+1`, successor current | Append the one expected predecessor qualification. |\n| Expected `N+2`, predecessor current | Compensation already committed; regenerate credentials, append nothing. |\n| Anything else | Leave service stopped and mark `RECOVERY_REQUIRED`. |\n\n### `scripts/nutricoach_v150_host_operations.py`\n\nChange:\n\n```python\nswitch_postimages(paths, candidate_digest, authority_pin_payload)\n```\n\nRequirements:\n\n- Require exactly one canonical candidate credential and one canonical authority pin credential.\n- Write successor candidate first and the fresh pin last, both `0400`.\n- Do not copy the predecessor pin.\n- Include both in `_postimages`.\n- Extend `post_fence()` to instantiate `FileCandidateAuthoritySource` from the successor pin and successfully authorize the successor without a predecessor snapshot.\n\nThe existing candidate-only switch test at `tests/test_nutricoach_v150_v14_safety.py:239-259` must become a candidate-and-pin test.\n\n### `scripts/nutricoach_v150_sealed_controller.py`\n\nInsert after weekly startup smoke and before systemd switch:\n\n```python\njournal.advance(\"AUTHORITY_PROMOTION_INTENT\")\nhost.promote_task26_authority()\njournal.advance(\"AUTHORITY_PROMOTED\")\nhost.switch_systemd()\n```\n\nThis is the latest safe point: installation and offline checks have completed, but no successor bytes are selectable yet. The present ordering is smoke → switch → reload → start (`scripts/nutricoach_v150_sealed_controller.py:188-199`).\n\nChange `RollbackGuard.rollback()`:\n\n1. Stop any active service.\n2. Call `restore_task26_predecessor()`.\n3. Restore the ordinary snapshot and remove successor-created paths.\n4. Reload/start only when both authority restoration and snapshot restoration succeeded.\n5. Verify predecessor authority after restart.\n6. Otherwise leave the service stopped and journal `RECOVERY_REQUIRED`.\n\nKeep the existing `COMMITTING + SUCCEEDED` linearization, but recovery must also verify the expected `N+1` successor head and successor pin before finalizing (`scripts/nutricoach_v150_sealed_controller.py:202-205,209-230`).\n\n### Next versioned preseal/verifier\n\nCreate the next closure as:\n\n```text\nscripts/prepare_nutricoach_v150_v15_preseal.py\nscripts/verify_nutricoach_v150_preseal_v15.py\ntests/test_nutricoach_v150_v15_safety.py\nscripts/rehearse_nutricoach_v150_v15.py\n```\n\nThe preseal must:\n\n- Read and seal the exact external baseline without appending.\n- Require the predecessor to be current and non-revoked.\n- Bind the predecessor’s existing qualification PASS digest.\n- Write `candidate-verification.json` before target construction and use its SHA-256 as `successor_historical_pass_digest`.\n- Declare exactly one success event and, conditionally, one rollback compensation event; replace the current `external_events_authorized: 0` contract (`scripts/prepare_nutricoach_v150_v14_preseal.py:205-229,354-368`).\n- Include both authority modules and the promotion tests in the detached controller closure. The bootstrap verifies every closure file before import (`scripts/nutricoach_v150_detached_bootstrap.py:52-77,152-177`).\n\nChanging the authority modules changes the canonical candidate because both are qualification-tool inputs (`gateway/platforms/task26_candidate_derivation.py:81-99,201-214`). Therefore the successor must be rebuilt and requalified; an existing candidate digest cannot be reused.\n\n## Append-only rollback semantics\n\nFor baseline count `N`:\n\n```text\nN+1: qualify(successor, successor_historical_pass_digest)\nN+2: qualify(predecessor, predecessor_historical_pass_digest)  # rollback only\n```\n\nNever delete or rewrite historical rows, never restore old authority files, and never restore an old pin.\n\nDo **not** revoke the predecessor during this transaction: revoked digests cannot be requalified (`gateway/platforms/task26_candidate_authority.py:114-117,211-218`). Do not automatically revoke the successor on an operational deployment failure either; after `N+2` it is non-current and therefore unauthorized. A later operator decision may revoke it, followed by another predecessor pin regeneration.\n\n## Why predecessor restoration is authorized\n\nAfter `N+2`, qualification semantics set the predecessor as current (`gateway/platforms/task26_candidate_authority.py:140-146,211-215`). The regenerated predecessor pin binds the `N+2` heads and count, so startup passes the exact-pin check (`gateway/platforms/task26_runtime_authority.py:123-126`). The predecessor candidate credential selects that same digest, and authorization accepts it as current and non-revoked (`gateway/platforms/task26_runtime_authority.py:146-157`).\n\nConversely, the successor retains its `N+1` pin. After compensation it is both stale and non-current, so accidental successor restart fails closed.\n\n## Required invariants\n\n- Service is confirmed stopped before the first external authority append.\n- No switch or start occurs without a verified successor `N+1` pin.\n- Predecessor is not invalidated at baseline.\n- Source ID and genesis never change.\n- Only the exact `N`, `N+1`, and `N+2` states above are accepted.\n- Registry and ledger sequence, predecessor hashes, cross-links, cardinality, and heads remain valid (`gateway/platforms/task26_candidate_authority.py:183-234`).\n- Pin count and heads are always derived from the verified chain.\n- Authority recovery precedes predecessor restart.\n- An authority restoration failure leaves the service stopped.\n- Successor credentials are successor-owned and removed by rollback; current cleanup already removes the successor root (`scripts/nutricoach_v150_concrete_host.py:501-509`).\n- The transaction ends at the durable `SUCCEEDED` commit marker. Failures after that are a separate rollback transaction, not an ambiguous continuation of this attempt.\n\nNo files were edited, tests were run, or live authority/service actions were performed.","run_stats":{"runtime_ms":719933,"turns":9,"tool_calls":59,"output_tokens":25649,"input_tokens":174687,"cache_read_tokens":638464,"total_tokens":838800,"generation_ms":714430,"tokens_per_second":36,"cost_usd":1.9621370000000002,"cache_hit_rate_last":0.9321037395171158,"cache_hit_rate_run":0.7851727415941196,"token_status":"complete","cost_status":"reported","duration_status":"monotonic"},"task_seq":0,"config_generation":0,"background_mode":"background"}