docs(handoffs): EchoTypes.jl EchoAggregation-mirror next-Claude brief

[hyperpolymath]

Docs-only. Adds a ready-to-paste next-Claude handoff that orients a fresh session on porting the general EchoAggregation (proofs/agda/EchoAggregation.agda, #175 — also covers #174) into the executable Julia companion EchoTypes.jl as a finite-domain falsifier.

What lands (commit c69db31)

• docs/handoffs/ECHOTYPES-JL-MIRROR-NEXT-CLAUDE-2026-06-27.adoc (new; CC-BY-SA-4.0) — a self-contained, paste-ready prompt plus human framing. It is filed in echo-types because echo-types is the Agda source of truth for the result being mirrored; the actual work happens in the separate EchoTypes.jl repo, which is not part of this session.

Why

The owner is moving work to the Claude Code desktop app and picked the EchoTypes.jl mirror as the next task. This brief travels with the repo so the desktop session can pick it up immediately, following the same handoff genre as oikos/docs/handoffs/OIKOS-NEXT-CLAUDE-2026-06-19.adoc.

Honest scope (carried into the brief)

• aggregation-as-fold is the fold's monoid-homomorphism law, not full SQL GROUP-BY semantics.
• avg is deliberately absent (not a monoid — express as sum / count).
• no-canonical-disaggregation refutes a section (left inverse), not a representative choice; the aggregate map is onto.

No proof content changed; the Agda side (#175) is already merged to main. Refs #175, #174.

🤖 Generated with Claude Code

https://claude.ai/code/session_01VwbFNQJw23tW8tqM7utWku

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Generated by Claude Code

[github-actions]

🔍 Hypatia Security Scan

Findings: 7 issues detected

Severity	Count
🔴 Critical	0
🟠 High	3
🟡 Medium	4

View findings

[
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    "type": "no_tests",
    "file": "/home/runner/work/echo-types/echo-types",
    "action": "flag",
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    "severity": "high",
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    "reason": "Issue in push-email-notify.yml",
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    "action": "flag",
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    "severity": "medium"
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  {
    "reason": "Code scanning (Hypatia): hypatia/workflow_audit/missing_timeout_minutes -- Hypatia workflow_audit: missing_timeout_minutes -- 2 day(s) old",
    "type": "CSA001",
    "file": "push-email-notify.yml",
    "action": "review",
    "rule_module": "code_scanning_alerts",
    "severity": "medium"
  },
  {
    "reason": "Code scanning (Scorecard): TokenPermissionsID -- Token-Permissions -- 24 day(s) old [STALE]",
    "type": "CSA001",
    "file": ".github/workflows/scorecard.yml",
    "action": "escalate",
    "rule_module": "code_scanning_alerts",
    "severity": "high"
  },
  {
    "reason": "Code-scanning alert TokenPermissionsID (high) at .github/workflows/scorecard.yml is 24 days old (threshold: 7 days) -- overdue for remediation",
    "type": "CSA003",
    "file": ".github/workflows/scorecard.yml",
    "action": "escalate",
    "rule_module": "code_scanning_alerts",
    "severity": "high"
  },
  {
    "reason": "Code-scanning alert hypatia/code_safety/agda_postulate dismissed as 'false positive' -- ensure dismissal is documented and justified",
    "type": "CSA004",
    "file": "proofs/agda/EchoImageFactorizationPropPostulated.agda",
    "action": "review",
    "rule_module": "code_scanning_alerts",
    "severity": "medium"
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]

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