# Formal Cross-Links in the design/ Ledger — Design Spec

**Date:** 2026-05-19
**Status:** Draft — awaiting user spec review
**Authors:** Brummel (orchestrator) + Claude

## Goal

Make the `design/` ledger a browsable wiki: replace informal prose
cross-references between contracts/models (`(see "Str ABI" below)`,
`(see design/contracts/0011-str-abi.md …)`, `see §"Data model"`) with
**formal, machine-checkable, file-level Markdown links**, and add an
in-tree hard gate that turns a broken cross-link into a same-commit
test failure instead of silent rot.

This is the positive completion of the DESIGN.md → design/ split.
That milestone established the negative half — *history prose must
not live in a contract* (`contracts_carry_no_decision_record_prose`,
clause-3). This milestone establishes the positive half — *what
cross-reference prose remains must resolve to a durable file*.
Together they form a complete invariant: every cross-reference in a
contract is **either** a resolving file-relative link into
`design/`-or-source, **or** decision-record prose that clause-3
already forbids.

The milestone has **no authoring surface**: it changes no `.ail`
program, no language construct, no compiler/checker/codegen path. It
is a documentation-form + Rust-test-infrastructure milestone, the
same category as the immediately-preceding DESIGN.md → design/ split
(`docs/specs/0045-design-md-rolesplit.md`), whose concrete code
was likewise the structural Rust pin plus the ledger shape, audited
clean. The no-`.ail` disposition is therefore precedent-governed and
reasoned, not an omission (see Concrete code shapes §"No authoring
surface").

## Architecture

Four locked design commitments (converged interactively this
session; the INDEX sub-choice was resolved by user MC during
brainstorm Step 2). They are the spec's input contract, not open
forks:

1. **File-level granularity, no in-file anchors.** A link addresses a
   whole file. Finer reference granularity is achieved by *splitting
   a file*, never by a `#fragment`. A link whose target is a pure
   `#anchor`, or carries a `#fragment` suffix, is a contract
   violation the hard gate rejects.

2. **Durable-tier targets only.** A formal link may target a file
   under `design/` (contracts + models) **or** a source file
   (`crates/**`, `runtime/**`). It may **never** target `docs/`
   (specs, plans, journals, or standing docs like
   `docs/PROSE_ROUNDTRIP.md`) — that is the *potentially ephemeral
   tracking* tier; linking the durable ledger into it re-couples
   exactly what the split decoupled.

3. **Standard relative Markdown link syntax** `[label](path)`. Not
   Obsidian `[[wikilinks]]`: wikilink name-fuzzy resolution is the
   prose-reference problem in another costume (it contradicts
   content-addressing), is not native on Gitea (the platform we
   actually use, self-hosted) nor in GitHub repo view, and does not
   uniformly address source files.

4. **File-relative path form for body prose; the INDEX spine stays
   repo-root-relative.** Body cross-links are
   `[label](./sibling.md)` / `[label](../models/x.md)` /
   `[label](../../crates/ailang-core/src/desugar.rs)`, resolved
   relative to the *containing file*. This is the universal standard
   (resolves in Gitea blob, GitHub, VS Code preview, Obsidian,
   static generators), serving the named primary goal (browsability)
   on every platform; its move-fragility is real but mechanically
   bounded by the resolve-check. The earlier "root-relative = the
   content-addressing thesis" argument was retracted as
   principle-overreach (the thesis kills name-fuzzy wikilinks;
   between two deterministic path forms it is an engineering trade).
   The **INDEX registry table** (`design/INDEX.md`) is a
   *deliberately-distinct structured tier*: it is machine-parsed as
   a table, and it is the one `design/` file whose path is
   structurally invariant (it is THE spine — it does not move). The
   move-fragility rationale that drove body prose to file-relative is
   *absent* for the spine, so the INDEX keeps its repo-root-relative
   cells and `design_index_pin.rs` clause-1 is **unchanged**.
   Forcing the body rule onto the spine would itself be the
   principle-overreach pattern this session already retracted once.

Derived scope boundaries (forced by the commitments + Step-1 recon,
not forks):

- **Intra-file directional prose is out of scope.** "the constraints
  below", "Direction 1 above", "see §X below" *within the same
  document* is not a cross-*file* reference; it has no file-link
  form (same file) and anchors are forbidden by commitment 1.
  These stay as prose. The remedy for "this file is too big for
  'above' to be clear" is commitment 1's file-split — a separate
  future concern, explicitly NOT this milestone.
- **Homeless references — three dispositions (clause-6), in
  priority order.** A cross-reference whose referent has no durable
  home is: **(a)** retargeted to the durable `design/`-or-source
  file that *actually carries that content* today, if one exists;
  else **(b)** the parenthetical pointer is removed while the
  surrounding present-tense behavioural prose is preserved verbatim
  — the ledger *describes* the behaviour, it does not point into
  the non-durable tier; else **(c)** deleted outright **only if the
  reference itself is relitigation residue** (clause-3-class).
  Recon-confirmed canonical instance:
  `design/models/0003-pipeline.md:61` and
  `design/models/0001-authoring-surface.md:180`, both
  `(see docs/PROSE_ROUNDTRIP.md)`, cite the *prose-mediator cycle /
  `ail merge-prose`* — content
  `design/contracts/0009-roundtrip-invariant.md` does **not** carry
  (that contract is the orthogonal hashing / parse-determinism
  invariant). (a) is therefore unavailable and the content is real
  current behaviour, not relitigation, so the disposition is
  **(b)**: drop the `(see docs/PROSE_ROUNDTRIP.md)` pointer, keep
  the surrounding `ail merge-prose` prose intact. Enumerating every
  instance is the recon's job; the *policy* is the spec's.
- **A cross-*file* `§"Section"` reference becomes a file-link.**
  `(see §"Data model" …)` pointing at content in *another* file
  becomes `[Data model](data-model.md)` — the section title may
  survive only as the human link *label*, never as a `#fragment`
  (commitment 1). The reader lands on the file and finds the section
  by reading; that is file-level granularity working as designed,
  not a loss. (A `§"Section"` that names a section of the *same*
  file is intra-file directional prose — the bullet above — and is
  untouched.)

## Scope — what counts as a cross-reference

The milestone formalises **navigational cross-references**, not
every nominal mention of a file or symbol. The discriminator:

- **In scope (a cross-reference):** a *navigational pointer* — the
  reader is being told to go look elsewhere. Forms: `(see "Title"
  …)`, `(see §"Section" …)`, `(see <path>)`, `… as in <X> …`, a
  bare in-prose path inside a `(see …)`, or a directional `…
  below`/`… above` whose named target is a **different file**.
  These convert to file-relative `[label](path)` Markdown links.
- **Out of scope (not a cross-reference):** a *nominal mention* of
  a source symbol or path in explanatory prose — "the desugarer
  `ailang-core::desugar` lowers loop-recur", "the box layout in
  `crates/ail-embed/src/lib.rs`". Naming the implementation is not
  pointing the reader at a document to read. Linkifying these would
  make the milestone "hyperlink the whole ledger" rather than
  "formalise the cross-references" — a different, unrequested
  change. They stay as prose. Commitment 2 *permits* a `crates/**`
  link target only for the case where a genuine navigational `(see
  crates/… )` pointer exists — e.g. `scope-boundaries.md:88` `see
  \`ailang-core::desugar\`` converts to
  `[desugar](../../crates/ailang-core/src/desugar.rs)` — never for
  a nominal mention.
- **Out of scope (schema-example documentation):** a `see §"…"`
  annotation *inside a fenced code block* — recon+corpus-confirmed:
  the `//`-comments in `data-model.md`'s fenced `jsonc` schema
  examples (lines 38/66/79 inside the 30–87 fence; 206/226 inside
  the 203–228 fence) — documents the schema example, not the
  browsable ledger. It is the inline-annotation analog of the
  nominal-mention carve-out: a `//` comment in a code example is
  code documentation, not a "go browse there" pointer. It stays as
  the informal `see §"…"` annotation, untouched. clause-5
  correspondingly does not scan fenced regions (a `](` inside a
  fence is literal text, not a navigable link — a gate-correctness
  requirement independent of this carve-out).

Two byte-policies the conversion applies (Boss-adjudicated from
recon Open Questions; the planner does not re-open them):

- **Iter-provenance suffixes are stripped on conversion.** A
  reference like `see §"Class names" / mq.1` carries a
  clause-3-class iter token. Converting yields
  `[Class names](typeclasses.md)` — the ` / mq.1` provenance is
  removed (it is exactly what clause-3 forbids; the
  clause-3 ∘ clause-5 composition requires its removal, not its
  survival riding on a now-formal link).
- **A directional phrase with no quoted title and no `(see …)`
  form stays prose.** `embedding-abi.md:51` "the frozen value
  layout below specifies" has no title to become a link label and
  is not a `(see …)` pointer — descriptive directional prose, left
  untouched. (The genuine cross-file pointer for that referent is
  the *separate* `embedding-abi.md:45` `(see "Frozen value layout"
  below)`, which does convert.)

## Concrete code shapes

### No authoring surface — the delivered concrete code

There is no `.ail` because the milestone touches nothing in the
language: no construct, no type rule, no codegen, no fixture. Per
the brainstorm infra clause, the rationalisation to refuse is "no
surface so no code to show"; the honest response is to show the
concrete code the milestone *does* deliver. For a docs-form +
test-infra milestone that is (a) the new Rust hard-gate clause,
(b) the real prose-reference before→after, (c) the explicit
no-change statement for clause-1. All three are shown below. The
governing precedent is the immediately-preceding same-category
milestone (DESIGN.md → design/ split), whose spec led its concrete
code with the Rust pin and the ledger shape and was audited clean —
this milestone follows that precedent exactly.

### (a) The new hard gate — `design_index_pin.rs` clause-5

A new test in the existing `crates/ailang-core/tests/design_index_pin.rs`
(sibling of clauses 1–4; reuses the file's `root()` helper and the
clause-3 `fs::read_dir` walk idiom verbatim). It is RED-first via an
embedded synthetic-vector self-check before it asserts the live tree
(a tree-scan test cannot be RED-first by tree state alone — the tree
is GREEN-vacuous until the first ref is converted — so the RED proof
is an in-test malformed-link vector, the honest mechanism for
"scan-the-tree" gates).

```rust
#[test]
fn design_body_links_are_durable_and_resolve() {
    // clause 5 — every inline Markdown link in design/ body prose
    // (contracts/ + models/, NOT INDEX.md — the spine is the
    // structured registry tier resolved by clause-1, commitment 4)
    // resolves, relative to its CONTAINING file, to an existing
    // file under design/ or source (crates/** | runtime/**); never
    // under docs/; never an in-file #anchor. Fenced code blocks are
    // not scanned (a `](` inside ``` is literal text, not a link).
    // Composes with clause-3: a surviving cross-reference is a
    // resolving durable file-link or it is clause-3-forbidden
    // decision-record prose.

    // Fenced code (``` … ``` / ~~~ … ~~~) is literal text, not
    // Markdown — a `](` inside a fence is NOT a navigable link on
    // any renderer. Strip fenced regions before scanning (gate
    // correctness: prevents false extraction of code-example byte
    // sequences and of non-rendering in-fence links).
    fn strip_fences(md: &str) -> String {
        let mut out = String::new();
        let mut in_fence = false;
        for line in md.lines() {
            let t = line.trim_start();
            if t.starts_with("```") || t.starts_with("~~~") {
                in_fence = !in_fence;
                continue; // drop the fence marker line itself
            }
            if !in_fence {
                out.push_str(line);
                out.push('\n');
            }
        }
        out
    }

    // link target := first capture of  \]\(([^)]+)\)
    // (matches [x](y) and the ](y) of image ![x](y) alike — every
    //  parenthesised target must resolve; conservative on purpose)
    fn targets(md: &str) -> Vec<String> {
        let mut out = Vec::new();
        let b = md.as_bytes();
        let mut i = 0;
        while i + 1 < b.len() {
            if b[i] == b']' && b[i + 1] == b'(' {
                if let Some(end) = md[i + 2..].find(')') {
                    out.push(md[i + 2..i + 2 + end].trim().to_string());
                }
            }
            i += 1;
        }
        out
    }

    // classify a repo-relative resolved path
    fn is_durable(repo_rel: &str) -> bool {
        repo_rel.starts_with("design/")
            || repo_rel.starts_with("crates/")
            || repo_rel.starts_with("runtime/")
    }

    // RED-first synthetic vectors (proves the gate bites before it
    // is pointed at the live tree).
    {
        let t = targets("see [x](../docs/specs/foo.md) and [y](#sec) and [z](./gone.md)");
        assert_eq!(t, vec!["../docs/specs/foo.md", "#sec", "./gone.md"]);
        assert!(!is_durable("docs/specs/foo.md"));   // durable-tier reject
        assert!("#sec".starts_with('#'));            // in-file anchor reject
        // fenced code is not a link surface (gate correctness)
        assert!(targets(&strip_fences("```\nsee [E](e.md)\n```\n")).is_empty());
        assert_eq!(targets(&strip_fences("[k](k.md)\n```\n[n](n.md)\n```")), vec!["k.md"]);
    }

    let bases = ["design/contracts", "design/models"];
    for base in bases {
        let dir = root().join(base);
        for entry in fs::read_dir(&dir).expect("design/ subdir exists") {
            let p = entry.unwrap().path();
            if p.extension().and_then(|e| e.to_str()) != Some("md") {
                continue;
            }
            let raw = fs::read_to_string(&p).unwrap();
            let fname = format!("{base}/{}", p.file_name().unwrap().to_string_lossy());
            for tgt in targets(&strip_fences(&raw)) {
                if tgt.starts_with("http://")
                    || tgt.starts_with("https://")
                    || tgt.starts_with("mailto:")
                {
                    continue; // external — out of the ledger's scope
                }
                let file_part = tgt.split('#').next().unwrap_or(&tgt);
                assert!(
                    !file_part.is_empty(),
                    "clause-5: in-file #anchor link {tgt:?} in {fname:?} \
                     — commitment 1 forbids fragments; split the file"
                );
                // resolve RELATIVE TO THE CONTAINING FILE
                let resolved = p.parent().unwrap().join(file_part);
                let canon = resolved
                    .canonicalize()
                    .unwrap_or_else(|e| panic!(
                        "clause-5: link {tgt:?} in {fname:?} does not resolve: {e}"
                    ));
                let repo_rel = canon
                    .strip_prefix(root().canonicalize().unwrap())
                    .unwrap_or(&canon)
                    .to_string_lossy()
                    .replace('\\', "/");
                assert!(
                    is_durable(&repo_rel),
                    "clause-5: link {tgt:?} in {fname:?} targets the \
                     non-durable tier ({repo_rel:?}); commitment 2 \
                     permits design/ + crates/ + runtime/ only"
                );
            }
        }
    }
}
```

`#[test]` count in the file goes 4 → 5; clauses 1–4 are byte-
unchanged. The exact byte form of the extractor/regex is the
planner's to finalise against this shape; the *contract* is the
four predicates (resolves-from-containing-file; durable-tier;
no-fragment; fenced-code-not-scanned) and the RED-first synthetic
vector.

### (b) Real prose-reference before → after

Three real, in-tree references (recon-confirmed line numbers; exact
bytes are the planner's):

```
design/contracts/0005-float-semantics.md:100  (the tidy precedent, still
  half-formal: bare root path in prose, not a Markdown link)
- before:  … a fresh heap-Str slab at the call site (see
           design/contracts/0011-str-abi.md for the dual realisation).
- after:   … a fresh heap-Str slab at the call site (see
           [Str ABI](str-abi.md) for the dual realisation).
           # float-semantics.md and str-abi.md are siblings in
           # design/contracts/ ⇒ file-relative target is `str-abi.md`

design/contracts/0003-embedding-abi.md:45  (informal AND stale-direction
  — the exact wart class motivating the milestone: "below" but the
  target is a different file)
- before:  … layout is **frozen as of M3** (see "Frozen value
           layout" below); …
- after:   … layout is **frozen as of M3** (see
           [Frozen value layout](frozen-value-layout.md)); …

design/models/0003-pipeline.md:61 + design/models/0001-authoring-surface.md:180
  (the canonical HOMELESS references — `(see docs/PROSE_ROUNDTRIP.md)`
  into the non-durable tier; recon proved roundtrip-invariant.md
  does NOT carry the merge-prose-cycle content ⇒ clause-6
  disposition (b), not a retarget)
- before (shape):  … the prompt template `ail merge-prose`
                   composes (see docs/PROSE_ROUNDTRIP.md).
- after  (shape):  … the prompt template `ail merge-prose`
                   composes.
           # disposition (b): the (see docs/…) pointer is removed;
           # the surrounding present-tense behavioural prose about
           # `ail merge-prose` is preserved verbatim. Exact bytes
           # (recon-confirmed pipeline.md:60-61,
           # authoring-surface.md:180-181) are the planner's per
           # the planner Iron Law.
```

### (c) clause-1 is unchanged (commitment 4, INDEX = spine)

```
crates/ailang-core/tests/design_index_pin.rs
  fn link_target_exists(cell) { … root().join(path).exists() }   // UNCHANGED
  fn every_index_link_resolves() { … }                            // UNCHANGED
```

The INDEX table cells stay repo-root-relative
(`design/contracts/0011-str-abi.md`); clause-1 keeps resolving them via
`root().join`. No INDEX content edit, no clause-1 resolver edit.
One resolution rule per *tier* (registry-spine: root-relative;
movable body prose: file-relative), each locally justified — not
one rule everywhere, by deliberate design.

## Components

| Component | Disposition |
|---|---|
| `crates/ailang-core/tests/design_index_pin.rs` | **Modify** — add clause-5 (`design_body_links_are_durable_and_resolve`); clauses 1–4 byte-unchanged; module `//!` extended one sentence to name clause-5. |
| `design/contracts/*.md`, `design/models/*.md` | **Modify** — every genuine cross-*file* prose reference rewritten to a file-relative Markdown link; homeless refs retargeted-or-deleted; intra-file "above/below" untouched (out of scope). |
| `design/INDEX.md` | **Untouched** — spine tier, commitment 4. |
| `docs/journals/2026-05-19-design-decision-records.md` | **Untouched** — monolithic append-only relitigation archive; never a link target (commitment 2/7). |
| `design/contracts/0007-honesty-rule.md` | **Modify (prose only)** — one sentence stating cross-references are formal file-relative links into the durable tier (the positive-half companion to the clause-3 sentence it already carries). Pin-safe: the two `docs_honesty_pin.rs` phrases stay verbatim+contiguous. |
| `bench/architect_sweeps.sh` | **Untouched** — clause-5 ("does every link resolve into the durable tier?") and Sweep-1 ("does any line carry a history anchor: `Iter <n>`, a date, `**Status:`?") are orthogonal predicates over the same files. A Markdown link `[label](file.md)` contains no Sweep-1 anchor token, so converting prose to links cannot trip Sweep-1; clause-5 shares no regex or scope with it. No sweep change. |

## Data flow

`cargo test` → clause-5 reads each `design/contracts/*.md` and
`design/models/*.md` → extracts every `](…)` target → for each:
external? skip. `#`-fragment or empty file-part? fail (commitment
1). Else resolve against the *containing file's directory*,
canonicalize, strip the repo root → repo-relative path → assert
under `design/`|`crates/`|`runtime/` (commitment 2). The synthetic
vector runs first and unconditionally (RED-first proof). clause-1
independently resolves INDEX cells root-relative (unchanged).

## Error handling

Every failure is a `panic!`/`assert!` naming the file, the offending
target, and which commitment it violates ("non-durable tier",
"in-file #anchor — split the file", "does not resolve"). No silent
skips except the three external schemes. A homeless reference that
recon cannot map to a durable home is not worked around in the test
— it is deleted from the prose as clause-3-class content (the test
then passes because the reference is gone, which is the correct
outcome, not a dodge).

## Testing strategy

- **RED-first:** clause-5's embedded synthetic-vector block asserts
  the extractor + durable classifier reject a `docs/specs/…` target
  and recognise a `#anchor` *before* the tree walk. Planner scripts
  the first task as: add clause-5 (RED on the synthetic vector if
  the classifier is stubbed wrong) → make the vector GREEN → then
  convert prose refs until the tree walk is GREEN.
- **Composition with clause-3:** a per-milestone assertion (journal,
  not code) that on the post-milestone tree, for every
  `design/contracts/*.md`, clause-3 GREEN ∧ clause-5 GREEN — i.e.
  every cross-reference is a resolving durable link or it is gone.
- **Whole-suite gate:** `cargo test --workspace` GREEN, count
  unchanged except +1 test. `design_index_pin` 5/5.
- **No bench surface:** zero codegen/runtime change ⇒ the regression
  trio is expected pristine; any firing is the tracked-P2 noise,
  causally exonerable as in the M2/M3/M5 and the just-closed split.

## Acceptance criteria

1. `crates/ailang-core/tests/design_index_pin.rs` has a 5th test
   `design_body_links_are_durable_and_resolve`; clauses 1–4 are
   byte-identical to HEAD `2ee4087`.
2. clause-5 is demonstrably RED-able (the synthetic vector fails if
   the durable classifier, the anchor check, or the fence-skip is
   wrong) and GREEN on the final tree.
3. Every *navigational* cross-*file* reference (per §"Scope — what
   counts as a cross-reference") in `design/contracts/` and
   `design/models/` is a file-relative `[label](path)` Markdown
   link resolving (from its containing file) to an existing
   `design/`-or-source file — OR, for a homeless reference, is
   disposed per clause-6 (a)/(b)/(c). Nominal source-symbol mentions
   and in-fence schema annotations are NOT linkified (out of scope).
   Iter-provenance suffixes on converted refs are stripped. The
   recon-and-corpus-verified touch-set is **closed and exhaustive**:
   - **convert (8 prose refs):** `float-semantics.md:69`
     (§"Prelude (built-in) classes" → `typeclasses.md`),
     `float-semantics.md:100` (bare path → `str-abi.md`),
     `embedding-abi.md:45` ("Frozen value layout" →
     `frozen-value-layout.md`), `memory-model.md:44` (§"Data model"
     → `data-model.md`), `memory-model.md:105` (§"Method dispatch"
     → `typeclasses.md`), `scope-boundaries.md:48` ("Str ABI" →
     `str-abi.md`), `scope-boundaries.md:88` (splits:
     `ailang-core::desugar` →
     `../../crates/ailang-core/src/desugar.rs` AND "Pipeline" →
     `../models/0003-pipeline.md`).
   - **disposition (b):** `pipeline.md:61`,
     `authoring-surface.md:180` — the `(see docs/PROSE_ROUNDTRIP.md)`
     pointer removed, surrounding `ail merge-prose` prose kept.
   - **stay prose (out of scope):** `data-model.md`
     38/66/79/206/226 (in-fence `jsonc` schema annotations),
     `embedding-abi.md:51` (no quoted title / no `(see)` form),
     every intra-file "above/below".
4. No reference in `design/` targets `docs/` (any subtree) or
   carries a `#fragment`.
5. `design/INDEX.md` and clause-1 are byte-unchanged; the
   decision-records journal is byte-unchanged and unlinked.
6. Intra-file "above/below" directional prose is untouched
   (recon-enumerated as out of scope, not missed).
7. `cargo test --workspace` GREEN; bench trio exit 0 or
   causally-exonerated per the standing P2 disposition.
8. `honesty-rule.md` carries the positive-half sentence; its two
   `docs_honesty_pin.rs` pinned phrases remain verbatim+contiguous.
