[Tracking] Error taxonomy

[AbdelStark]

Context

Tracking issue for the Error taxonomy subsystem.

Source of truth

• RFC: rfcs/0012-*.md
• Spec corpus: docs/spec/01-architecture.md (module boundaries)

Scope

This tracker collects the implementation issues for the Error taxonomy subsystem.
Children inherit the spec links from their parent RFC.

Acceptance Criteria

• All child issues closed
• Subsystem RFC moved from Draft to Accepted
• CHANGELOG updated under the next release

Child issues

• errors: implement GenoLeWMError hierarchy and ERROR_CODES registry #21 — errors: implement GenoLeWMError hierarchy and ERROR_CODES registry (area:errors · type:feature · priority:p0 · effort:m)
• errors: AST linter raise_geno_lewm_error and registered_error_code #22 — errors: AST linter raise_geno_lewm_error and registered_error_code (area:errors · type:ci · priority:p0 · effort:s)

[AbdelStark]

Status update (autonomous burndown session, 2026-05-20).

This tracking issue's child issues received the following treatment in this session:

The session shipped 16 implementation PRs (#103, #105, #106, #107, #108, #109, #110, #111, #112, #113, #114, #115, #116, #117, #118, #119) closing 16 child issues across the foundation chain (errors, observability, action types, provenance primitives, public-API snapshot, AST linters).

Every remaining open child issue under this tracker has received an explicit per-issue comment with one of three classifications:

• Blocked: requires ML runtime / external data / export toolchains / cryptographic substrate / desktop toolchain not present in the session environment.
• Deferred: small / medium scope, ready to pick up in a follow-up session against the foundations now in place.
• Out of scope: covered by another shipped artifact or superseded.

This tracker stays open until all child issues close.

[AbdelStark]

All child issues complete: #21 (error hierarchy + ERROR_CODES) and #22 (raise_geno_lewm_error / registered_error_code AST linters) both merged. The runtime contract is enforced by tools/lint/check_error_codes.py on every PR; the documented exit-code table at docs/spec/04-error-model.md is consumed by the CLI dispatcher at geno_lewm/cli/_dispatch.py (PR #135).