odd: P1.2 closeout ledger + P1.3.1 forward handoff

[klappy]

Closeout docs for the 2026-04-19 session that landed oddkit 0.18.0 (encode DOLCHEO + governance_source envelope). New ledger captures the arc and the recency-as-authority failure pattern. New handoff points the next session at P1.3.1 — challenge's governance_source retrofit. Prior post-closeout handoff marked superseded with banner.

What's in this PR

• odd/ledger/2026-04-19-p1-2-encode-dolcheo-landed.md (new, tier 3, stable)
  DOLCHEO-format retrospective. Timeline 18:32–21:04Z. What shipped in 0.18.0 (governance_source, DOLCHEO batch prefixes, letter dedup, 6-letter minimal fallback). Sonnet 4.6 validator VERIFIED 11/11 with external corroboration (main's orchestrate.ts bytes, core-governance-baseline §Canon-Only citation, live-response dedup verification). Open items with priority bands. Names the recency-as-authority failure pattern that recurred three times in the session.

• odd/handoffs/2026-04-20-p1-3-challenge-canary.md (new, tier 3, stable)
  Forward-pointing handoff. Scope: retrofit oddkit_challenge envelope to declare governance_source. Same canary shape as encode, smaller delta (challenge already has four canon-reading discovery helpers). Path-3 workflow. Standing rules. Reference material. Thin prompt.

• odd/handoffs/2026-04-20-post-closeout.md (superseded)
  status → superseded, superseded_by pointer added, banner at doc top directs readers to the new handoff. Content preserved for provenance.

Evidence

• oddkit PRs referenced: odd/handoffs: 2026-04-20 P1.2 encode batch-mode + canary refactor (for fresh session) #114 (feat, 290dde5) and odd/handoffs: use Writing Canon Summary — extraction key on P1.2 handoff #115 (promotion, e6dbba5)
• Prod state: oddkit.klappy.dev/health returns 0.18.0; envelope smoke 61/61 × 3 consecutive runs
• Validator session: sesn_011CaDj48ax5VEXyMfxrDves under agent_011CaDj46VwmidBz5g3wMhdJ (VERIFIED)

Not in scope

• Handoff-text correction on odd/handoffs/2026-04-20-p1-2-encode-canary.md (Tier 2 "bundled" → "minimal" rename). Recorded as O-open P3 in the new handoff. Tiny separate PR.
• Canon principle on contract-governs-handoff-drift. Recorded as O-open P4. Watch for one more recurrence before committing to the doc ("Use Only What Hurts").

References

• klappy://odd/ledger/2026-04-19-p1-2-encode-dolcheo-landed (this PR)
• klappy://odd/handoffs/2026-04-20-p1-3-challenge-canary (this PR)
• klappy://canon/constraints/core-governance-baseline
• klappy://canon/definitions/dolcheo-vocabulary
• klappy://canon/principles/agent-self-report-under-stress

---

Note

Low Risk
Documentation-only changes that add new operational guidance and status metadata; no product/runtime behavior is modified.

Overview
Adds a new session ledger (odd/ledger/2026-04-19-p1-2-encode-dolcheo-landed.md) capturing the P1.2 closeout for oddkit 0.18.0 (what shipped, validator evidence, timeline, and forward open items).

Introduces a new forward handoff (odd/handoffs/2026-04-20-p1-3-challenge-canary.md) that scopes and prescribes the next work unit (P1.3.1: retrofit oddkit_challenge to emit governance_source/governance_uri, plus test/tooling expectations).

Marks the previous post-closeout handoff as superseded, adding status: superseded, a superseded_by pointer, and a top-of-doc banner redirecting readers to the new handoff.

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