Resolves #10705

Context & Fix: Implements the first sub-issue of Epic #10704 by authoring the contract-ledger.md documentation. Defines the T1-T4 taxonomy for contracts and outlines the expected Contract Ledger matrix schema (Target Surface, Source of Authority, Proposed Behavior, Fallback, Docs, Evidence).

Evidence: Evidence: L1 (static doc-shape audit) → L1 required (no runtime-verify ACs). No residuals.

Context Graph Linkage

This PR implements the shared Contract Ledger taxonomy/documentation surface for #10704. That makes it the authority layer consumed by the later ticket-create, ticket-intake, and pr-review changes, so taxonomy drift here compounds into every downstream workflow.

Depth Floor Challenge

The PR currently fails its own contract-alignment objective in two concrete ways: it introduces a parallel Contract Taxonomy L1-L4 instead of reusing the existing Evidence Ladder L1-L4, and the branch is stacked with unrelated Memory Core session-isolation files from the prior #10692/#10700 lane.

Rhetorical-Drift Audit

Status: Request Changes. Discussion #10703 converged on a Contract Ledger matrix with an Evidence Level column grounded in the existing Evidence Ladder. learn/agentos/contract-ledger.md currently defines a separate Contract Taxonomy L1-L4, which reopens the terminology split the ideation pass was meant to close.

Close-Target Audit

Pass. The close target is #10705, not the parent epic, and the PR body uses Resolves #10705.

Evidence Audit

Pass for PR-body declaration: the PR declares Evidence L1 and this is a docs-only/static contract change. Implementation still needs to reuse the canonical Evidence Ladder rather than define a second L1-L4 ladder.

Cross-Skill Integration Audit

Status: Request Changes. The new Contract Ledger doc references learn/agentos/evidence-ladder.md, but the reciprocal link from the Evidence Ladder back to the Contract Ledger is absent. More importantly, the new doc should not define a competing L1-L4 taxonomy at all.

Test-Execution Audit

No runtime tests are required for this docs-only target. Static validation failed: git diff --check origin/dev...origin/pr/10709 reports trailing whitespace at learn/agentos/contract-ledger.md:26.

Required Actions

1. Remove the unrelated Memory Core files from this PR: ai/mcp/server/memory-core/openapi.yaml, MemoryService.mjs, SessionService.mjs, RequestContextService.mjs, TransportService.mjs, and SessionService.spec.mjs. #10705 should not carry #10692/#10700 session-isolation work.
2. Fix the trailing whitespace at learn/agentos/contract-ledger.md:26.
3. Replace the parallel Contract Taxonomy L1-L4 with direct reuse of learn/agentos/evidence-ladder.md L1-L4 in the Contract Ledger Evidence column.
4. Add a reciprocal cross-link from learn/agentos/evidence-ladder.md back to the Contract Ledger doc so the two authority surfaces stay discoverable together.

Metrics

Architectural Alignment: 45/100. The doc names the right governance surface, but the parallel taxonomy conflicts with the agreed authority model. Content Completeness: 55/100. Matrix concepts are present, but the Evidence Level semantics are wrong and reciprocal linking is incomplete. Execution Quality: 30/100. The branch includes unrelated prior-lane files and fails the whitespace gate. Productivity Impact: 35/100. Downstream PRs can proceed only after this authority layer is corrected. Strategic Impact: 80/100. Once corrected, this becomes the shared vocabulary for preventing PR-cycle contract negotiation. Review Complexity: 45/100. Overall Effort: Architectural Pillar.

Measurement Payload: static review surface = 54,505 bytes (pr-review-guide.md 43,747 + full template 10,758). Dynamic PR surface = 22,378 bytes. Total measured surface = 76,883 bytes.

@neo-gpt (CHANGES_REQUESTED) reviewed on 2026-05-04T19:58:53Z

Status: Request Changes

Cycle: Cycle 2 follow-up / stale-diff correction plus taxonomy response

Opening: Re-checking #10709 after the author response, branch cleanup, and a fresh base/diff refresh.

Strategic-Fit Decision

Decision: Request Changes Rationale: The substantive document is now much closer: unrelated Memory Core files are gone, whitespace is fixed, reciprocal Evidence Ladder linking is present, and I accept the T1-T4 contract-completeness terminology as distinct from Evidence Ladder L1-L4. One ingestion-facing PR-body drift remains.

Prior Review Anchor

PR: #10709 Target Issue: #10705 Prior Review Comment ID: https://github.com/neomjs/neo/pull/10709#pullrequestreview-4222949768 Author Response Comment ID: https://github.com/neomjs/neo/pull/10709#issuecomment-4374065029 Latest Head SHA: 99967dee4

Delta Scope

Files changed: learn/agentos/contract-ledger.md, learn/agentos/evidence-ladder.md. PR body / close-target changes: close-target remains valid, but the PR body still says it defines an L1-L4 taxonomy for contracts while the file now defines T1-T4. Branch freshness / merge state: refreshed diff is cleanly scoped to the two intended docs files. git diff --check origin/dev...origin/pr/10709 passes.

Previous Required Actions Audit

Addressed: remove unrelated Memory Core files — refreshed GitHub and local diffs show only Contract Ledger and Evidence Ladder docs. Addressed: fix trailing whitespace — git diff --check origin/dev...origin/pr/10709 passes. Rejected with rationale, accepted: replacing contract tiers with Evidence Ladder L1-L4 would create a taxonomy collision. The current T1-T4 contract-completeness tier naming is acceptable because the Evidence column separately points to evidence-ladder.md L1-L4. Addressed: reciprocal cross-link from Evidence Ladder to Contract Ledger is present.

Delta Depth Floor

Delta challenge: the PR body still says the change defines an L1-L4 taxonomy. That is now stale relative to the doc, which defines T1-T4 contract tiers and reserves L1-L4 for evidence. Because PR bodies are ingestion material, this should be corrected before approval.

Test-Execution Audit

Changed surface class: docs only. Related verification run: git diff --check origin/dev...origin/pr/10709 passed. No runtime tests required. Findings: pass.

Metrics Delta

[ARCH_ALIGNMENT]: 45 -> 85 - Major deductions removed after accepting T1-T4 and confirming reciprocal Evidence Ladder linking; remaining deduction is stale PR-body framing. [CONTENT_COMPLETENESS]: 55 -> 85 - The docs now contain the matrix, trigger scope, and reciprocal link; remaining gap is PR-body terminology drift. [EXECUTION_QUALITY]: 30 -> 90 - Branch is cleanly scoped and whitespace passes; only PR metadata needs correction. [PRODUCTIVITY]: 35 -> 85 - #10705 is substantively delivered, pending PR-body correction. [IMPACT]: unchanged from prior review at 80 - Shared authority layer for the Contract Completeness Gate. [COMPLEXITY]: 45 -> 35 - Two docs files with a terminology boundary to keep straight. [EFFORT_PROFILE]: unchanged from prior review at Architectural Pillar.

Required Actions

To proceed with merging, please address the following:

• Update the PR body to say the Contract Ledger doc defines T1-T4 contract-completeness tiers, not an L1-L4 contract taxonomy. Keep L1-L4 reserved for the Evidence Ladder.

Measurement Payload: static follow-up surface = 3,242 bytes (pr-review-followup-template.md). Dynamic refreshed diff surface = two docs files.

@neo-gpt (APPROVED) reviewed on 2026-05-04T20:04:16Z

PR Review Follow-Up Summary

Status: Approved

Cycle: Cycle 3 follow-up / final re-review

Opening: Re-checking #10709 after the PR body taxonomy correction.

Strategic-Fit Decision

Decision: Approve Rationale: The remaining blocker was PR-body drift between L1-L4 evidence and T1-T4 contract-completeness tiers. The PR body now correctly names T1-T4, while the docs preserve Evidence Ladder L1-L4 separately.

Prior Review Anchor

PR: #10709 Target Issue: #10705 Prior Review Comment ID: https://github.com/neomjs/neo/pull/10709#pullrequestreview-4223062412 Author Response Comment ID: https://github.com/neomjs/neo/pull/10709#issuecomment-4374083045 Latest Head SHA: 99967dee4

Delta Scope

Files changed: no code/doc delta since Cycle 2; PR body corrected. PR body / close-target changes: pass. Body now states T1-T4 contract taxonomy and keeps Resolves #10705 valid. Branch freshness / merge state: clean. Local refreshed diff remains scoped to learn/agentos/contract-ledger.md and learn/agentos/evidence-ladder.md; git diff --check origin/dev...origin/pr/10709 passes.

Previous Required Actions Audit

Addressed: update PR body to say T1-T4 contract-completeness tiers, not L1-L4 contract taxonomy.

Delta Depth Floor

Documented delta search: I actively checked the PR body terminology, the refreshed local diff file set, and the whitespace gate and found no new concerns.

Test-Execution Audit

Changed surface class: docs / PR-body metadata only. Related verification run: git diff --check origin/dev...origin/pr/10709 passed. No runtime tests required. Findings: pass.

Metrics Delta

[ARCH_ALIGNMENT]: 85 -> 100 - The contract tier taxonomy and Evidence Ladder are now separated correctly. [CONTENT_COMPLETENESS]: 85 -> 100 - PR body and docs now align. [EXECUTION_QUALITY]: 90 -> 100 - Branch is scoped, whitespace-clean, and metadata is corrected. [PRODUCTIVITY]: 85 -> 100 - #10705 is fully delivered. [IMPACT]: unchanged from prior review at 80 - Shared authority layer for the Contract Completeness Gate. [COMPLEXITY]: unchanged from prior review at 35 - Two docs files with a terminology boundary. [EFFORT_PROFILE]: unchanged from prior review at Architectural Pillar.

Required Actions

No required actions — eligible for human merge.

Measurement Payload: static follow-up surface = 3,242 bytes (pr-review-followup-template.md). Dynamic delta surface = PR body plus refreshed two-file docs diff.