3As of 2026-10-30. The plan is [spec/implementation-plan.md](spec/implementation-plan.md); each milestone ends with its checks passing on a fake ship.
5| # | Milestone | Status |
7| 1 | Parser and mark | Done (7c739b7; the doc's grammar decisions of 2026-10-30 in ab797a9) |
8| 2 | Types and prelude | In progress. [prompts/milestone-2.md](prompts/milestone-2.md) briefs the developer; the checker and importer are partial |
9| 3 | Core language | Not started |
10| 4 | Host and static pages: the first release | Not started |
11| 5 | Published pages | Not started |
12| 6 | Islands | Not started |
13| 7 | Tooling | Not started |
14| 8 | Polish | Not started |
16The plan sets no dates: "agree them after milestone 1, once it shows how fast the Hoon work goes". They haven't been agreed yet. Milestone 1's commits run from 2026-10-29 18:13 UTC to 2026-10-30 11:50 UTC.
18On 2026-10-30, @iko decided that Jibb drops `$?`, so a `+$` takes a union's cases on the lines below its name. [prompts/drop-union-rune.md](prompts/drop-union-rune.md) records the change before milestone 2. The repository spec records the decision; the Claude document still needs to be synchronized.
20## Milestone 2: in progress
22The repository spec records the subsequent type-system and prelude decisions; those changes also need synchronization to the Claude document. An initial inference fragment and a standalone Hoon type reader are being tested. The fragment explicitly reports that it does not check a module; partial bridges pass selected Hoon atoms, term singletons, nested faced or unfaced cells, supported disjoint unions and opaque standard collections from `/sur` molds and marks into inference. Collections retain their names and supported arguments for printing and unification; nested supported union arguments are retained too. The bridge trusts unchanged results from the source-aware reader; a materialized type graph alone cannot reveal cases Hoon already collapsed. The source-validated standard prelude `list` mold shares this representation with imported lists; other Jibb-written collection molds and most prelude collection operations remain unsupported; malformed names and arities fail closed. Selected self-recursive `/sur` molds cross as opaque module-and-name identities; aliases, foreign references, recursive marks, unfolding and construction remain unsupported. The reader handles mark samples, recursive molds whose origins can be verified through Ford imports, nested collections, direct ordered maps, certain ordered-map fields, direct `$^` unions whose cases can be proved disjoint, and one verified explicit union argument in a list, set, map or unit. Ambiguous recursive origins fail closed; recognizable explicit unions are checked from source before Hoon can collapse their cases, as @iko confirmed for imported `$%`, `$?` and `$^`, while other nested unions, nested ordered maps, general union disjointness and complete import integration remain unfinished. Opt-in structured reader APIs preserve successful graphs and distinguish definite unsupported-aura and core evidence from failures the reader cannot prove; unverified union disjointness and name-only vase recognition remain unsupported. They revalidate and re-walk failed types. An opt-in partial checker entry point consumes unchanged reader results and reports definite aura or core errors at imported mold use sites when their inputs are unique. Ordered replay covers nested cell samples, record and function casts, and non-generic same-module aliases; unsupported prefixes, cycles and shadowing stop it. Union molds, generic applications, transitive modules and unsupported reader outcomes remain generic. Replay repeats inference and may add work. The partial checker resolves a subset of ordinary library imports in dependency order using supplied Jibb sources and a source-derived partial prelude interface, caches completed interfaces per run, and detects missing sources and cycles. It does not yet check API or kind semantics, and the prelude inventory is incomplete. The inference fragment supports unrestricted `@`, selected one-way widenings including aura-family ancestors, generalized atom constraints arising from explicit capitals or bare sample binders, acyclic local value definitions with captures, selected single self-recursive top-level and local gates, simple and nonrecursive generic mold aliases, selected faced record casts and field reads, and contextual tags, `~` and constructors for closed disjoint unions, including direct nonrecursive generic unions and propagation through complete loobean and unit-shaped branches in casts and known union-sample calls, including nested branches. Multi-argument calls form a right-nested sample, retain known faces and shared type variables, and can use known sample positions to contextualize list and union arguments. A definite mismatch points to the failing argument when the fragment can establish it, otherwise to the combined sample; unsupported contextual forms still fail closed. For a supported recursive gate, the checker infers the sample first and uses its exact type, including field faces, for one monomorphic self reference. It generalizes after the body is checked; subsequent uses instantiate it independently. Incompatible recursive arguments can report the gate and argument sites. For a complete loobean branch with one direct self-call arm, a separately inferred closed base type can seed the recursive result before the whole body is checked. Open or pending base types do not seed it; other branch shapes remain subject to the fragment’s existing limits. A supported single local recursive gate also uses a monomorphic self reference and generalizes variables free of the enclosing environment after checking its body; captured variables remain shared. The checker collects written capitals per `++` before inference, excluding nested definitions: a capital used in an enclosing definition is shared with its locals even when written later, while a capital introduced only in a local definition is generalized there. Sibling locals can introduce independent capitals with the same spelling; generic mold parameters keep their own scope. Mutual groups, polymorphic recursion and value cycles remain unsupported. Reporting repeats inference for a recursive gate, so its performance cost remains unmeasured. String interpolation accepts known atom auras, unrestricted `@`, tapes and isolated decimal literals; a known cell asks for a printer, and an explicitly generic atom asks for an aura. Loobeans, term singletons, non-tape collections, open types and a type fixed only later remain unsupported. Contextual null-headed cells fit their cases, but do not supply a `|=%$` constructor; unresolved nulls remain pending and are reported separately from tags. A known union of `~` and a null-headed cell supports a complete `~` / `[~ value]` branch in either order, including shadow checks; unknown subjects, missing or duplicate arms, and unresolved branch results remain unsupported. This fragment infers the prelude’s `fall` and `need` signatures. With the validated prelude list and a known cast or gate sample, empty, nonempty and nested list literals infer their element types, including contextual union tags; a mismatched element names both sites. In that context `~` and zero-valued terms fit an empty list, and two-item unfaced cells form cons lists, including nested cons and imported-list contexts; invalid heads or tails name both sites. Faced or longer cells and a missing or altered prelude list fail closed. A known list result also supplies context through complete loobean, unit-shaped and list-shaped branches, including recursive and nested branches. For a known standard list with a supported element type, a complete `~` / `[item rest]` branch infers the element and tail types in either arm order and checks binders for shadowing. Uncontextualized list construction, unknown subjects, unsupported element types and other or incomplete list patterns remain unsupported. A value with type variable `A` can fit a field whose type is that same `A`, including in generic union payloads and nested or repeated record fields. Other variable-dependent face merges remain unsupported. Forced equality of distinct written capitals now reports both source sites, following @iko’s decision; forcing one to a concrete type remains unsupported. Imported record spines with repeated faces fail closed where used, but only with a generic unsupported diagnostic. Hoon may erase unfaced nested-cell boundaries, so the check can conservatively reject valid names in distinct erased scopes. Supported closed unions print using an in-scope name or imported alias; an unnamed nongeneric union prints its cases, parenthesized when nested. The latter is print-only. Generic union types retain all arguments in their printed name; if that name is unavailable, the partial printer reports the limitation. Different import faces for the same origin remain compatible; compatibility across distinct union origins and some generic-argument comparisons remain unsupported. Nonrecursive generic aliases can reorder, repeat or omit parameters while retaining a union’s origin, including through local scopes and library interfaces. A generic union declared directly inside a body remains unsupported, as do differing-variable face constraints in a union payload. A transitive generic union whose name is unavailable is reported as unsupported instead of hiding its arguments. Unfixed decimal literals default to `@ud` in gate-free inferred types; mutually recursive local groups and recursive molds, general branch tag context, other constraint cases and defaulting inside gate types still need work. Collection recognition checks the originating core and fails closed on shadows or unsupported Ford subject shapes; a wrapper regression also rejects forged subjects, samples and tails. Its golden fixtures include three real Tlon files. A Clay test passes a Ford-built nested union through the reader into partial inference. The partial prelude includes `murn`, `join`, `snip`, `rear` and the newly agreed shared-type `clap`, parsed but still awaiting checker and backend validation, and [prelude-inventory.md](prelude-inventory.md) is a source audit, not the complete inventory or signatures. The milestone remains unfinished.
24The shared prelude interface reserves every name present in the supplied vendored source and makes only supported inferred entries available, including `list`, `unit`, `same`, `fall`, `need`, `lure`, `weld` and `snoc`. The validated standard `list` mold is injected when the prelude’s own gates are inferred; `weld` has an ordinary explicit result cast. An absent or altered `list` is not injected, and an altered declaration cannot leak through direct or transitive mold aliases. List-dependent prelude mold aliases remain unsupported because their templates are prepared before injection. Unsupported entries such as most list helpers remain reserved but unavailable; backend validation of the helpers remains outstanding. All callers use the same prelude origin, so a library can export a type containing unqualified `(unit A)` to another module. Preparation rejects empty, malformed, conflicting or import-bearing source; the prepared value is trusted and must come unchanged from `+prepare-prelude`. The module-scope fixture compares the prepared and source-taking paths against the real prelude and a two-module golden under eval and on the ship. The source and checker remain incomplete, so this does not establish complete shadowing coverage or a checked module.
26## Milestone 1: parser and mark
28What the plan asks for, and where it is:
32| The `%jibb` mark as the first tab gives it | `jibb-dev/mar/jibb.hoon`, as the doc writes it |
33| The layout pass, emitting INDENT, DEDENT and NEWLINE | `+layout` in `jibb-dev/lib/jibb.hoon`, designed in its section 2 |
34| A parser for the Grammar tab's EBNF that returns a syntax tree with source positions | `+parse` and `+parse-tokens`, section 3. Every node has a span, its start and end, and `+check-spans` tests the spans of every tree the golden tests print |
35| Errors with file, line, column and an excerpt | `+show-error`, section 4.3. Each error points at the first character where the text stops being the start of any valid module (section 2.0) |
36| Done when every Jibb code block in the doc parses | The doc labels its 14 Jibb blocks `jibb`. Each is a golden case, `tests/golden/doc-*`, and `tools/doc-blocks docs/spec` checks that they match. All parse; the one block written as an error, the Grammar's buttons example, has a type error for milestone 2 |
37| Done when each lexical rule has a test input that breaks it | The `lex-*` golden cases: for each lexical rule, inputs that break it (`-bad-`), each with the error's expected place, and inputs that keep it (`-ok-`), except for the forms Jibb leaves out (the closers, blob and `@c` literals) |
38| Done when `\|commit` stores `.jibb` files on a fake ship | `tools/ship check-commit`: 7 checks, from reading every file back byte for byte to three-way merges |
40Besides the plan's list:
42- 515 golden cases: 299 that parse and 216 that fail, each failure at a stated line and column. One failing case has an unclear expectation (corpus question 3). The newer type-output cases exercise only the partial inference fragment. Each case's `about.txt` quotes the doc's words it tests.
43- The 515-case corpus passed under `urbit eval` in 58.3 s. The fake ship passed all 521 tests, including the importer, importer/checker and mark/checker bridges, module scope and unification checks, with 32.6 s for sync and 37.9 s for tests. The importer golden compares 149 projections; `tools/clay-fixtures` builds the example Hoon fixtures through Clay, checks a recursive Ford import's origin, and passes Clay-built types through the Clay-built importer and partial checker.
44- `tools/testdata/selftest` (22 checks) and `tools/testdata/ship-selftest` test the tools themselves.
45- Two independent audits before 7c739b7, one of which compared the library with a reference parser written in Python from the doc over about 19,000 generated programs. Before ab797a9, a second Python parser, written from the decisions, agreed with the library on 8,000 generated programs and 900 hand-written probes.
46- Speed: starting `urbit eval` and building the library takes about 8 s. After that, a 2,000-line module of 400 definitions parses in about a second. Loops over definitions, arms, lines and items grow no stack; nesting costs a few stack frames a level, and 100,000 nested brackets still parse (library section 3).
50| Commit | Date | What |
52| 1cb51df | 2026-10-29 | Foundation: the parser's design, the tools, the desks, the vendored base-dev and landscape files, the golden corpus |
53| 15a5545 | 2026-10-29 | The layout pass |
54| 3c5f50a | 2026-10-29 | The parser |
55| 7c739b7 | 2026-10-30 | Fixes from two independent audits; milestone 1 done |
56| 5a4aa73 | 2026-10-30 | `tools/doc-blocks`, after the doc labelled its Jibb blocks |
57| ab797a9 | 2026-10-30 | The 12 grammar decisions of 2026-10-30: four changed the parser, eight confirmed it |
58| aad6ddb | 2026-10-30 | Drop `$?`; `+$` takes union cases below its name |
59| 1dd92a6 | 2026-10-30 | Begin type inference and Hoon imports |
60| 51ce4d9 | 2026-10-30 | Extend partial inference and importer, record type and prelude decisions |
61| be6d2a5 | 2026-10-30 | Add atom widening, nested collections and case-local Hoon import fixtures |
62| 26554ac | 2026-10-30 | Infer an atom constraint, extend the prelude and read example molds through Clay |
63| fbeaa83 | 2026-10-30 | Extend atom constraints and nested ordered-map imports; connect Clay types to partial inference |
64| 47a1f49 | 2026-10-30 | Read validated Ford imports, widen aura families, and show both sites of selected errors |
65| bd37989 | 2026-10-30 | Read mark samples and test partial mark imports; reject unproven nested `$^`; preserve atom constraints through aliases |
66| 2d5deb2 | 2026-10-30 | Default gate-free decimal types, validate named Hoon mold lookup, and isolate fixture failures |
67| 1b7dbae | 2026-10-30 | Infer acyclic local definitions and parse case-local Jibb module fixtures |
68| 8b9c9ac | 2026-10-30 | Preserve recursive import origins, infer simple local molds, and supply Jibb module sources to the partial checker |
69| 529736a | 2026-10-30 | Infer supported library import graphs and guard nested Hoon `$^` in collections |
70| 8bf1b12 | 2026-10-30 | Infer selected record faces and check nested `$^` in static Hoon records |
71| d8ac47d | 2026-10-30 | Cache library interfaces, preserve imported Hoon record faces, and check nested tagged unions |
72| edd9277 | 2026-10-30 | Infer nonrecursive generic mold aliases with lexical parameters |
73| 4406f6f | 2026-10-30 | Resolve selected contextual tags and check explicit imported unions |
74| 5c73614 | 2026-10-30 | Print supported named and escaping union types |
75| 0070584 | 2026-10-30 | Propagate union context through loobean branches, read selected unions in Hoon collections, and add `flit` |
76| 250564c | 2026-10-30 | Infer selected named generic unions, test Hoon collection wrappers, and add list helpers |
77| e95ef8f | 2026-10-30 | Bridge selected Hoon unions into partial inference and support generic union aliases |
78| 56a899f | 2026-10-30 | Infer matching variable types in faced fields and bridge opaque Hoon collections |
79| 4d45d2f | 2026-10-30 | Resolve selected contextual null literals |
80| e878edc | 2026-10-30 | Infer complete unit-shaped branches and bridge selected recursive Hoon molds |
81| 743dfd8 | 2026-10-30 | Propagate union context through unit-shaped branches |
82| 3f90fa8 | 2026-10-30 | Share a partial prelude interface across module inference |
83| 29bd39f | 2026-10-30 | Infer contextual list literals and validate prelude parity |
84| a2a6ef5 | 2026-10-30 | Infer complete list-shaped branches |
85| 671fe72 | 2026-10-30 | Infer contextual list nulls and cons cells |
86| 7e69436 | 2026-10-30 | Infer selected self-recursive gates |
87| 9ab52e8 | 2026-10-30 | Infer recursive branches with closed base types |
88| d782b45 | 2026-10-30 | Propagate list context and apply settled type decisions |
89| c7082e0 | 2026-10-30 | Infer multi-argument calls |
90| 918acbd | 2026-10-30 | Infer recursive gates from their samples first |
91| 1470d18 | 2026-10-30 | Infer selected prelude list helpers |
92| 10cbf9c | 2026-10-30 | Infer selected local recursive gates and distinguish reader diagnostics |
93| 45afb13 | 2026-10-30 | Infer local capital scopes and report direct reader diagnostics |
94| 054e651 | 2026-10-30 | Report nested reader diagnostics |
95| This change | 2026-10-30 | Infer known-aura string interpolation |
99On a machine set up as [development.md](development.md) says:
102tools/golden # 515 cases under urbit eval
103tools/importer-test # the Hoon importer fixture projection
104tools/type-import-test # the importer/checker bridge fixture
105tools/type-mark-test # the mark/checker bridge fixture
106tools/type-module-scope-test # module and prelude scope fixture
107tools/hoon check-spans-test # prints <<>> when the span checker works
108tools/testdata/selftest # the tools themselves
109tools/doc-blocks docs/spec # the doc's examples are golden cases
111tools/ship gen-tests --check # tests/lib/jibb.hoon is up to date
112tools/ship test # the same 515 cases as -test arms on the ship
113tools/testdata/ship-selftest
114tools/ship check-commit # |commit stores .jibb files
115tools/clay-fixtures # example /sur files and marks build through Clay
118## What milestone 1 leaves to later milestones
120- Errors carry a start only. Spans keep each node's end so that milestone 2's type errors can underline both conflicting sites with excerpts (library section 1).
121- The parser accepts forms for the checker to judge: `[]`, `[a]`, `m()`, `!! a`, and the module kinds. `[]` and `m()` have since been decided to be errors, and `[a]` is `a`; the parser has not changed. The Grammar's buttons example parses, though the doc marks it as a type error.
122- Grammar questions the doc's author hasn't been asked follow the readings in [open-questions.md](open-questions.md).
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