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Sync README and roadmap status across echo and bridge tracks
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README.md

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# echo-types
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Constructive Agda formalization of echo types / fibers:
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Constructive Agda development for echo types as a first-class notion of structured loss:
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loss that is not total erasure.
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## Core Idea
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Most formalisms foreground two clean cases:
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- reversible / injective / linear-ish: no important loss
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- ordinary irreversible: loss occurs and is usually forgotten
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Echo types target a third case:
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- irreversible, but with a retained proof-relevant constraint on what was lost
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This repository treats that third case as the primary object of study.
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## Definition (Foundation)
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Given `f : A → B`, define the fiber/echo at `y : B`:
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`Echo f y := Σ (x : A) , (f x ≡ y)`
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This repository provides a minimal, explicit development in ordinary intensional dependent type theory (`--safe --without-K`) with:
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Current formal foundation is in:
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- `proofs/agda/Echo.agda`
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- `proofs/agda/EchoCharacteristic.agda`
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- `proofs/agda/EchoResidue.agda`
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- `proofs/agda/EchoExamples.agda`
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- `proofs/agda/EchoChoreo.agda`
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- `proofs/agda/EchoEpistemic.agda`
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- `proofs/agda/EchoLinear.agda`
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- `proofs/agda/EchoGraded.agda`
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- `proofs/agda/EchoTropical.agda`
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- `proofs/agda/EchoIntegration.agda`
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with constructive proofs (`--safe --without-K`, no postulates in `proofs/agda`):
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- `echo-intro` (introduction into own fiber)
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- `map-over` (action on fibers for morphisms over fixed base)
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- `map-over-id` (identity law)
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- `map-over-comp` (composition law)
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- `map-square` (action along commuting squares)
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Characteristic M2 results include:
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- explicit non-injectivity witnesses for collapse maps
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- impossibility of full reconstruction from plain visible output (`no-section-*` family)
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- distinct echoes over the same visible value (`echo-true≢echo-false`, `stateA≢stateB`)
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- retained-constraint theorem for projection-style structured loss (`visible-constraint`)
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Scope-broadening stages now include:
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- choreographic bridge (`RoleEcho` over role projections, commuting-square transport)
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- epistemic bridge (indistinguishability and echo-indexed knowledge)
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- affine/linear bridge (strict weakening from full echoes to residues)
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- graded bridge (grade order and compositional degradation law)
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- tropical bridge (argmin-style witness residues under tropical collapse)
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- integration bridge (knowledge preservation under choreography plus controlled graded degradation)
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- indexed/relational/categorical packaging (`EchoIndexed`, `EchoRelational`, `EchoCategorical`, `EchoScope`)
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- cross-ecosystem bridges (`EchoCNOBridge`, `EchoJanusBridge`, `DyadicEchoBridge`, `EchoOrdinal`)
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## Current Status Snapshot (2026-04-23)
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On `main`, the following are true:
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- full suite compiles: `agda -i proofs/agda proofs/agda/All.agda`
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- core echo/fiber laws are smoke-pinned (`echo-intro`, `map-over`, `map-over-id`, `map-over-comp`, `map-square`)
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- non-injectivity/no-section family is present (`collapse-non-injective`, `no-section-collapse`, `no-section-visible`, `no-section-collapse-to-residue`, `no-section-weaken`)
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- distinct-witness and retained-constraint exemplars are present (`echo-true≢echo-false`, `stateA≢stateB`, `visible-constraint`)
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- fiber introduction (`echo-intro`)
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- action on fibers over a fixed base (`map-over`)
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- identity law (`map-over-id`)
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- composition law (`map-over-comp`)
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- action along commuting squares (`map-square`)
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Ordinal/Buchholz track status:
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## Controlled Scope Broadening
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- `Ordinal.Buchholz.WellFounded` provides `wf-<ᵇ : WellFounded _<ᵇ_` for the currently admitted constructor core
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- top-marker `bplus` bridges are admitted and inverted: `<ᵇ-+ω`, `<ᵇ-+ψω`, `<ᵇ-inv-+Ωω`, `<ᵇ-inv-+ψω`
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- open work remains for general `Ω/+` and `ψ/+` comparisons and shared-binder cases (`<ᵇ-ψα`, `<ᵇ-+2`) in a `--without-K`-compatible style
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The formal scope is extended in controlled phases:
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## External Bridge Targets (local workspace)
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- Phase A (`proofs/agda/EchoIndexed.agda`): role-indexed echoes `Echoᵢ` with trace-level witness separation.
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- Phase B (`proofs/agda/EchoEpistemicResidue.agda`): residue-based epistemic echoes `EchoR` with strict weakening/no-section results.
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- Phase C (`proofs/agda/EchoRelational.agda`): relational semantics `Step : S → O → Set` and output fibers `Σ s , Step s o`.
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- Phase D (`proofs/agda/EchoCategorical.agda`): slice/fibration packaging over the compiled deterministic and relational layers.
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Current bridge targets in this workspace are:
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- `absolute-zero`: `/var/mnt/eclipse/repos/verification-ecosystem/maa-framework/absolute-zero`
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- `januskey`: `/var/mnt/eclipse/repos/developer-ecosystem/januskey`
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- `tropical-resource-typing` (potential target, not recently audited): `/var/mnt/eclipse/repos/verification-ecosystem/tropical-resource-typing` (upstream: `https://github.com/hyperpolymath/tropical-resource-typing`)
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Note: `januskey` is not currently nested under `maa-framework` in this workspace layout.
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Cross-repo status:
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- bridge formalisms live in this repo (`EchoCNOBridge`, `EchoJanusBridge`, tropical-collapse witness work in `EchoTropical`)
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- end-to-end conformance against upstream codebases is a separate track and is not yet fully machine-checked here
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- see `docs/echo-types/roadmap.md` for staged cross-repo verification gates
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## What Echo Types Are For
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Echo types are useful when outputs are:
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- insufficient to reconstruct their source exactly
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- still sufficient to constrain the source non-trivially
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Intended proof-use cases include:
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- non-injective computation
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- provenance
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- structured irreversibility
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- partial recoverability
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- classification up to equivalence
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- forensic inference from residues
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- refined taxonomies of information loss
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## Identity Claim and Falsifiability
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This repo is trying to establish echo types as a concept with its own identity.
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Since `Echo` is built from sigma/fiber machinery, identity will not come from syntax.
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It must come from role and theorems.
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We treat the claim as established only if all three are met:
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1. Distinct phenomenon: structured loss under non-injective computation.
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2. Characteristic theorem family: results that are naturally echo-shaped, not just generic sigma lemmas.
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3. Canonical examples: cases where echo type is the right explanatory unit.
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If these fail, we record that result and stop the identity claim.
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## Build
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```bash
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cd /var/mnt/eclipse/repos/echo-types
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agda -i proofs/agda proofs/agda/Echo.agda
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agda -i proofs/agda proofs/agda/All.agda
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for f in proofs/agda/*.agda; do agda -i proofs/agda "$f"; done
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```
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## Bridge to Certified Null Operations (CNOs)
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Full suite:
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This repository now includes a theoretical bridge to **Certified Null Operations (CNOs)** from the [Absolute Zero](https://gitlab.com/maa-framework/6-the-foundation/absolute-zero) project.
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```bash
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cd /var/mnt/eclipse/repos/echo-types
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agda -i proofs/agda proofs/agda/All.agda
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```
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**Key Insight**: CNOs are singleton echo types over identity functions.
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## Roadmap
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**Bridge Modules**:
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- `proofs/agda/EchoCNO.agda` - Basic bridge with core theorems
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- `proofs/agda/EchoCNOBridge.agda` - Comprehensive bridge with full mapping
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Proof milestones and decision gates are in:
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**Documentation**: See `docs/ECHO-CNO-BRIDGE.adoc` for detailed explanation.
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- `roadmap.adoc`
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- `docs/buchholz-plan.adoc`
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**Main Theorems**:
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- `cno-echo-equivalence`: CNOs ≃ singleton echoes over identity
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- `all-cnos-are-echos`: All state-preserving programs are echoes over identity
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- `cno-composition-echo`: CNO composition preserves echo structure
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Open/gated work and cross-repo follow-ups are tracked in:
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This bridge enables:
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- Using echo type theory for CNO verification
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- Cross-repository theorem sharing
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- Unified foundation for structured loss and null operations
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- `docs/echo-types/roadmap.md`
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- `docs/echo-types/taxonomy.md`
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- `docs/echo-types/composition.md`

docs/echo-types/roadmap.md

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**Status:** planning document. Partitions work by dependency on the
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two identified bottlenecks:
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- **Bottleneck B1.** The `--without-K` shared-binder irreflexivity
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block in the Buchholz `_<ᵇ_` order (`claude/buchholz-order-def`
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branch). Blocks full totality + WF of Buchholz notation; everything
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downstream that needs ordinal semantics is gated on this.
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- **Bottleneck B1.** The `--without-K` shared-binder constructor
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block in the Buchholz `_<ᵇ_` order. `wf-<ᵇ` is landed for the
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currently admitted core, but full totality + full-constructor
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well-foundedness remain gated on a K-free treatment of the shared-
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binder cases.
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- **Bottleneck B2.** Tool-scope limitations on adjacent repos
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(`maa-framework`, `januskey`, `absolute-zero`). Blocks end-to-end
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audit of the CNO and Janus bridges.
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(`maa-framework/absolute-zero`, `januskey`,
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`tropical-resource-typing`). Blocks end-to-end bridge audits.
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Paths marked **[unblocked]** can proceed today. Paths marked
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**[gated on B1]** or **[gated on B2]** cannot.
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Requires the shared-binder constructors, which the current Agda
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2.6.3 `--without-K` blocks via pattern-matching. Either an Agda
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upgrade or a rank-embedding proof strategy unblocks this.
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- **[gated on B1]** Well-foundedness `WellFounded _<ᵇ_`.
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Technically independent of irreflexivity if done via
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rank-embedding, but conventionally proved after totality.
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- **[gated on B1]** Extension of totality + well-foundedness proofs to
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the full constructor set (including shared-binder cases such as
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`<ᵇ-ψα` and `<ᵇ-+2`).
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- **[gated on B1]** Ordinal semantics of BT terms: denotation
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`BT → Ordinal` preserving order. Requires a formal `Ordinal` type
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as a prerequisite, which is itself downstream of WF.
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- **[gated on B2]** Janus reversible-file-operations bridge
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verification against `januskey`'s actual API. Needs cross-repo
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access.
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- **[gated on B2]** Tropical-resource-typing alignment: first do a repo
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inventory (it is currently not recently audited), then validate
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`EchoTropical` witness/residue claims against that neighbouring
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tropical typing development.
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- **[gated on B2]** `maa-framework` integration. Out of scope for
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the current tooling; needs scope expansion or file export.
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readme.adoc

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* `proofs/agda/Echo.agda`
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* `proofs/agda/EchoCharacteristic.agda`
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* `proofs/agda/EchoResidue.agda`
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* `proofs/agda/EchoExamples.agda`
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* `proofs/agda/EchoChoreo.agda`
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* `proofs/agda/EchoEpistemic.agda`
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* `proofs/agda/EchoLinear.agda`
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* graded bridge (grade order and compositional degradation law)
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* tropical bridge (argmin-style witness residues under tropical collapse)
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* integration bridge (knowledge preservation under choreography plus controlled graded degradation)
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* indexed / relational / categorical packaging (`EchoIndexed`, `EchoRelational`, `EchoCategorical`, `EchoScope`)
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* cross-ecosystem bridges (`EchoCNOBridge`, `EchoJanusBridge`, `DyadicEchoBridge`, `EchoOrdinal`)
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== Current Status Snapshot (2026-04-23)
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On `main`, the following are true right now:
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* Full suite compiles (`agda -i proofs/agda proofs/agda/All.agda`).
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* Core echo/fiber theorems are present and smoke-pinned (`echo-intro`, `map-over`, `map-over-id`, `map-over-comp`, `map-square`).
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* Characteristic non-injectivity/no-section family is present (`collapse-non-injective`, `no-section-collapse`, `no-section-visible`, `no-section-collapse-to-residue`, `no-section-weaken`).
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* Distinct-witness and retained-constraint exemplars are present (`echo-true≢echo-false`, `stateA≢stateB`, `visible-constraint`).
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Ordinal/Buchholz track status:
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* `Ordinal.Buchholz.WellFounded` provides `wf-<ᵇ : WellFounded _<ᵇ_` for the currently admitted constructor core.
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* Top-marker `bplus` bridges are now admitted and inverted:
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** `<ᵇ-+ω`, `<ᵇ-+ψω`
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** `<ᵇ-inv-+Ωω`, `<ᵇ-inv-+ψω`
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* Open work remains for general `Ω/+` and `ψ/+` comparisons and for the shared-binder cases (`<ᵇ-ψα`, `<ᵇ-+2`) in a `--without-K`-compatible style.
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== External Bridge Targets (local workspace)
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Current bridge targets in this workspace are:
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* `absolute-zero`: `/var/mnt/eclipse/repos/verification-ecosystem/maa-framework/absolute-zero`
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* `januskey`: `/var/mnt/eclipse/repos/developer-ecosystem/januskey`
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* `tropical-resource-typing` (potential target, not recently audited): `/var/mnt/eclipse/repos/verification-ecosystem/tropical-resource-typing`
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(upstream: `https://github.com/hyperpolymath/tropical-resource-typing`)
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Note: `januskey` is not currently nested under `maa-framework` in this workspace layout.
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Cross-repo status:
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* Bridge formalisms live in this repo (`EchoCNOBridge`, `EchoJanusBridge`, tropical-collapse witness work in `EchoTropical`).
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* End-to-end conformance against upstream codebases is a separate track and is not yet fully machine-checked here.
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* See `docs/echo-types/roadmap.md` for staged cross-repo verification gates.
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== What Echo Types Are For
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Proof milestones and decision gates are in:
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* `roadmap.adoc`
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* `docs/buchholz-plan.adoc`
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Open hard questions are tracked in:
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Open/gated work and cross-repo follow-ups are tracked in:
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* `docs/next-questions.adoc`
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* `docs/echo-types/roadmap.md`
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* `docs/echo-types/taxonomy.md`
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* `docs/echo-types/composition.md`

roadmap.adoc

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* If the claim can be established with precise theorems and examples, continue and scale.
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* If it cannot be established, document failure clearly and stop the identity claim.
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Document map (to keep status/docs aligned):
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* `README.md` / `readme.adoc`: current snapshot and build entry points.
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* `roadmap.adoc` (this file): canonical milestone log for the echo-theory track.
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* `docs/buchholz-plan.adoc`: canonical status for the ordinal/Buchholz WF track.
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* `docs/echo-types/roadmap.md`: gated and cross-repo follow-up queue.
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== Current Foundation (Established)
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File: `proofs/agda/Echo.agda`
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* `no-section-collapse`
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* `echo-true≢echo-false`
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* `visible-constraint`
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* `stateA≢stateB`
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* `state₁≢state₂`
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* `no-section-visible`
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* `transport-visible-not`
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