CR-DD-012A: Define governed decision foundation

[coreytshaffer]

Status

Documentation only. CR-DD-012A implementation authority remains explicitly withheld.

CR-DD-012A and any code or test work require a later, separate human approval
with a bounded implementation allowlist. This PR does not authorize
implementation or integration.

What this proposal defines

• Distinguishes SourceBytes, NormalizedComponentBytes, and authoritative
  AssembledExecutionBytes.
• Anchors future preview/execution parity to the immutable UTF-8 bytes of the
  established worker user-message representation.
• Pins current encoding, universal-newline, separator, ordering,
  duplicate-source, path-header, inline-input, and absent-input semantics.
• Requires immutable ownership of buffers and ordered collections.
• Requires explicit finite internal construction bounds without imposing a new
  public tc run CLI limit.
• Defines closed-schema canonical serialization, strict parsing, and
  domain-separated decision-ID verification.
• Requires a pure decision builder with all decision-relevant configuration
  supplied explicitly.
• Keeps raw task material attempt-local and limits persistent decision fields
  to bounded privacy-safe bindings.

Scope

Exactly four authorized documentation files:

• docs/change/requests/CR-DD-012A-governed-decision-foundation.md
• docs/current_backlog.md
• docs/architecture/daily_driver_orchestrator_spec.md
• docs/change/requests/CR-DD-012-shared-governed-run-decision.md
  (status/sequencing only)

No changelog, code, tests, runtime, CLI, ledger, artifact-contract, worker,
backend, routing, or cloud-authority changes are included.

Explicitly not authorized

• No integration with ordinary tc run or tc run --plan.
• No governed_run_plan.v2 or other plan-schema migration.
• No ledger changes or runtime-observation persistence.
• No worker/backend invocation, route execution, fallback enforcement, or
  saved-plan execution.
• No --confirmed-plan or authority inferred from confirmation or decision
  identity.

CR-DD-012B remains blocked until a separately approved CR-DD-012A
implementation lands and passes review.

Validation

• GitHub comparison against main: one commit ahead, zero behind, exactly four
  documentation files.
• git diff --check: passed.
• Proposal-only scope and authority language reviewed.
• Known local .fuse_hidden* and scratch artifacts remain untracked and
  excluded.
• Runtime test suite intentionally not run because this PR changes
  documentation only.

Final review gate

• Byte encoding, newline, separator, ordering, and absent-input semantics
  are pinned.
• AssembledExecutionBytes is the parity anchor; source bytes are
  non-authoritative provenance.
• Mutable inputs are not retained by reference.
• Finite construction bounds do not become a new public CLI limit.
• Canonical serialization is closed-schema and fail-closed.
• Decision building has no ambient or volatile dependencies.
• Persistent decision fields exclude prompts, content, paths, sensitive
  values, and secrets.
• Neither tc run path consumes the proposed foundation.
• No plan-v2, ledger, runtime-observation, or implementation authority is
  introduced.