Make ?- list tuples and handle typos and arity

[ajwdev]

Summary

Reworks the REPL's query UX around ?-.

• ?- rel, ?- rel() and ?- rel("c", _, ...) (a single atom with no named variables) now list whole matching tuples. No _N rule is created. _ and missing trailing arguments match anything.
• Queries with named variables or several atoms keep the existing binding path (X = v), including _ padding for partial atoms.
• Typos and arity mistakes are caught before evaluation. An unknown relation (not declared, not defined by a rule or fact, no EDB rows, not in the current store) prints Unknown relation 'x'. Did you mean: a, b? (up to 3 suggestions by edit distance, skipping _N results and x__rel snapshot copies). More arguments than a relation has columns prints rel has N columns, got M arguments.
• New output formats: compact (bare rel(a, b) tuples) and table (aligned columns under a header row; cells clipped at 64 characters, newlines escaped). table also applies to binding results, with the variable names as headers.
• The default listing names each column (Principal = "...", Namespace = ...), falling back to c0, c1 when a relation has no Decl.
• Help text updated.

Engine additions: CompiledProgram::defined_relations and Engine::known_relations.

Behavior changes

• The bare pred(args) / pred query form is removed. Non-command input prints Not a command. Queries start with ?-, e.g. ?- <line>, and an unknown ::cmd prints Unknown command: .... Use ?- pred(args).
• The plain output format is renamed default, with no alias. \format plain and --format plain are now rejected. The --format default is spelled default. (tests/smt_ndjson.rs is updated for the rename.)
• \format and --format accept compact and table in addition to default, pretty and ndjson.
• A ?- query naming an unknown relation, or passing too many arguments, is now an error instead of an empty result (interpreter) or an opaque error (DD).
• A ?- conjunction with no named variables prints No variables to bind. Name one (e.g. X). (previously a zero-column rule: No results. or a blank row).
• ::smt behavior and --format ndjson output are unchanged.

Testing

• cargo fmt --check, cargo clippy --all-targets --locked -- -D warnings, cargo test --all-targets --locked all pass on stable.
• Unit tests for body_relations, suggest, split_top_level_args, single_atom, render_table.
• New tests/repl_query.rs drives the binary over testdata/: default listing names columns, \format compact, \format table (header and rule row), unknown relation did-you-mean, too many arguments, plain rejected, bare direct_perm(X) prints the hint.
• Manual smoke on both the interpreter and --backend dd against testdata/: listing, partial atom, _ wildcard, binding query with :string:contains, typo'd relation, too many arguments, conjunction with no variables, every \format value. Output is identical on both backends.

Before / after

Listing (before, ?- direct_perm("developer@example.com") created a zero-column rule and printed a blank row):

before:
  
Found 1 result(s): (-> _0)

after:
  Principal = "developer@example.com", Namespace = "kube-system", ApiGroup = "*", Resource = "*", Verb = "*"
Found 1 result(s).

Typo and arity:

before:
?- direct_permz
No variables found - use uppercase names for variables.
?- direct_perm("a","b","c","d","e","f")
No variables found - use uppercase names for variables.

after:
?- direct_permz
Unknown relation 'direct_permz'. Did you mean: direct_perm, indirect_perm?
?- direct_perm("a","b","c","d","e","f")
direct_perm has 5 columns, got 6 arguments.

Formats:

\format compact
?- direct_perm("admin@example.com")
  direct_perm("admin@example.com", "", "*", "*", "*")

\format table
?- direct_perm("admin@example.com")
  Principal            Namespace  ApiGroup  Resource  Verb
  -------------------  ---------  --------  --------  ----
  "admin@example.com"  ""         "*"       "*"       "*"

\format ndjson   (before: {} ; after: keyed by column)
{"Principal":"admin@example.com","Namespace":"","ApiGroup":"*","Resource":"*","Verb":"*"}

\format plain
before: Output format: plain.
after:  Unknown format 'plain'. Use: default | compact | pretty | table | ndjson.

Removed bare form:

before:  direct_perm(X)   -> lists every direct_perm tuple
after:   direct_perm(X)   -> Not a command. Queries start with ?-, e.g. ?- direct_perm(X)

Binding queries are unchanged:

?- direct_perm(P, NS, R, V, G), :string:contains(P, "admin")
  P = "admin@example.com", NS = "", R = "*", V = "*", G = "*"
  P = "system:serviceaccount:pallograph-test:admin-sa", NS = "", R = "*", V = "*", G = "*"
Found 2 result(s): (-> _0)

🤖 Generated with Claude Code