Join on ancestor handle is forbidden

Platform spec ADR

Join on ancestor handle is forbidden

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Spec standingStandard

Owner

Piotr Mikstacki pmikstacki@cybernomad.it

Submitter

Piotr Mikstacki pmikstacki@cybernomad.it

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Completeness

OKfeature · 8 SpecSection(s) · 1 H2 heading(s)

Section id	Required	Found
what-this-feature-specifies	yes	yes
implementation-anchors	yes	yes

Full tree: run pnpm verify:platform-spec-layout (writes src/generated/platform-spec-layout-report.json).

Related spec docs

• Feature
  Fibers and spawn

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Context

Waiting on an ancestor handle while the ancestor may wait on descendants creates predictable deadlocks.

Decision

Join on a parent or ancestor Fiber<T> handle must be a compile error (JoinWouldDeadlock). Normative ordering for cancel + Join aligns with D-CORE-CONC-0014.

Consequences

Structured concurrency stays acyclic on the join graph; runtime need not recover ancestor joins.

Verification anchors

compiler/crates/beskid_analysis/; D-CORE-CONC-0014.