[bamboo] feat: project bounded child results with assignment provenance

[bigduu]

Focused child of #1054/#1048 and #791. Depends on the required packet foundation; immutable evidence-ref consumption also depends on its separate reader child. Existing result inspection has bounded slices/current_run_final but no assignment binding; automatic parent resume currently uses a separate larger compacted text envelope.

Acceptance slice

The authorized direct parent receives a small result attributable to one immutable assignment, through both explicit inspection and automatic parent resume. Runtime-verified identity/finality is distinguished from child-reported verification claims.

Acceptance criteria

• Typed result at most8KiB after actual JSON escaping includes outcome, summary, reported evidence/verification, proposals, blockers and open decisions. Keep detailed evidence in existing referenced artifacts/transcript.
• Derive direct-parent authority from trusted ToolCtx/persisted lineage. Expected assignment digest is a selector, never permission; bind actual child lifetime, assignment/source digest and terminal run evidence.
• Separate runtime-verified provenance/finality from model-reported claims. A child saying verified=true does not establish verified facts.
• Assignment changes, subsequent user input/non-final assistant, missing/modified refs or stale selector produce explicit stale/unavailable results; do not automatically adopt them.
• Apply the same contract and escaped-byte budget to SubAgent.get and child-completion parent resume. Reuse existing transcript plus SessionInbox and its recovery boundary.
• Real direct-parent inspection/resume tests prove stale source/result handling, missing refs, Unicode/escaping, automatic delivery budgets, restart/deduplication and safe persistence without cross-scope disclosure.

Scope and estimate

4–8 hours; result projection, existing inspection/child completion and Inbox envelope seams. If independent result storage, history retention or task-change CAS is necessary, split that protocol before implementation.

Non-goals

New result store, task-change authority, general retry scheduling, evidence truth certification, full transcript copying, roles, observer or remote placement.

Fresh isolated local worktree, independent local review and local merge; no GitHub PR review gate, push or Zenith gitlink update.

Implementation tracker and scope split

The original combined acceptance remains open in this tracking Issue. Current source lacks an immutable ContextRefs resolver and exact terminal callback/birth/assignment/run attribution; these cannot be inferred from a latest Assistant or callback timestamp. Audit: /private/tmp/bamboo-1344-readonly-seam-plan-audit.md. No implementation acceptance or automatic result/run guarantee is claimed.

• [bamboo] feat: inspect required-packet child reports with bounded snapshot provenance #1359 — explicit direct-parent required-packet typed result Inspect, strict selectors and honest durable-snapshot provenance, complete escaped ToolResult <=8KiB. Independently Ready; no callback/Inbox or file-verification dependency imported. Local source dd06976e, integration c0de2431; one native libtest actually executed all six cold Worker scenarios, Engine26/0/0, Tools165/0/0, Server74/0/0, independent local reviews and default affected/root check/Clippy/fmt accepted. Domain278 historical execution reused only after whole-crate source equality; automatic resume and private ContextRefs acceptance remain pending.
• Separate automatic completion/resume result publication: freeze exact terminal-source attribution first, preserve admit-before-wait-clear and checkpoint-before-ACK; bind semantic identity to actual birth/assignment/terminal source. Existing callback drops this identity and cannot certify a durable final save. Do not enable ActorDirectory/owned runtime to fill this gap inside the explicit result child.
• Immutable ContextRefs missing/modified verification remains [bamboo] feat: validate bounded immutable context refs for child background #1343 and its accepted authority-port prerequisite, after producer [bamboo] feat: produce compact canonical authority within atomic Main files #1358 and separately refined consumer [bamboo] perf: read Actor snapshots without scanning transcripts #1339. Opaque model-reported paths/digests are not checked files.

Default current snapshot truth, reported evidence and proposals remain distinct. The first child uses actual full Storage reads, keeps legacy Inspector/paging and unsupported worker gates, and is not completion of this tracker or #791. All implementation/reviews/merges remain local; GitHub tracking never gates independent authorized tasks.