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hyperpolymathclaude
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proof(SafeString): annotate 7 bodyless decls as OWED (Refs standards#158) (#54)
## Summary Converts the 7 bodyless declarations in `src/Proven/SafeString/Proofs.idr` from terse `Axiom:` doc-comments to the estate's OWED-with-justification convention established 2026-05-20 across SafeChecksum / Buffer / CryptoAccel / HKDF / Bloom / FPGA / SafeHtml / SafeCSV / SafeCORS / SafeAPIKey / SafeSemVer / SafeMath / SafeFile / SafeHeader / SafeHTTP / SafeArgs / SafeYAML / SafeOTP / SafeSQL / SafeNetwork: - Triple-pipe `|||` doc stating the claim + operational witness - `0 ` (erased multiplicity) so the postulate is not runtime-callable - Bare signature, no `postulate` keyword - Explicit Idris2 0.8.0 blocker + discharge condition Refs hyperpolymath/standards#158. ## The 7 OWED items Every blocker in this module is in the **opaque-String-FFI family** (as predicted in the assignment brief) — `pack`, `unpack`, `length`, `++`, `singleton`, `==` over `String` are all FFI-bound primitives that do not type-level reduce in Idris2 0.8.0. ### `concatLength` **Claim:** `length (s1 ++ s2) = length s1 + length s2`. **Blocker:** `String` `++` and `length` are FFI-bound primitives; no `pack`/`unpack` structural induction is available on opaque `String`. **Discharge:** `Data.String` reflective tactic for `length`/`++`, or exposing the packed-character list as a definitional equality. ### `trimNoWhitespace` **Claim:** if `all (not . isSpace) (unpack s) = True` then `trim s = s`. **Blocker:** `pack . unpack` round trip is FFI identity, not Refl. **Discharge:** reflective tactic for `pack . unpack`. ### `escapeHTMLSafe` **Claim:** `escapeHTML (singleton c) = singleton c` when `c` is not in `{&, <, >, ", '}`. **Blocker:** `pack (go (unpack (singleton c)))` chain does not normalise — `singleton`/`unpack`/`pack` all FFI-bound. **Discharge:** reflective tactic for `pack . singletonList = singleton`. ### `escapeSQLSafeProperty` **Claim:** `all (\c => c /= '\'') (unpack (escapeSQL s)) = True`. **Captured guarantee:** weaker "no unescaped quote in isolation" (the stronger paired-quote invariant noted as follow-up). **Blocker:** `unpack . pack . map f` over abstract `String`. **Discharge:** reflective tactic or induction principle on unpacked list. ### `escapeHTMLSafeProperty` **Claim:** `all (\c => c /= '<' && c /= '>') (unpack (escapeHTML s)) = True`. **Blocker:** same as `escapeSQLSafeProperty` (the `<` |-> "&lt;" / `>` |-> "&gt;" rewrite produces no raw `<`/`>` but the FFI round trip blocks Refl). **Discharge:** same as above. ### `splitJoinIdentity` **Claim:** `join (singleton delim) (split delim s) = s` when `delim` does not occur in `s`. **Blocker:** `splitHelper` returns `[pack (unpack s)]` — `pack . unpack = s` is FFI identity, not Refl. **Discharge:** reflective tactic for `pack . unpack`. ### `linesUnlinesApprox` **Claim:** `unlines (lines s) = s ++ ""` (the `++ ""` slack absorbs trailing-newline-handling between `splitHelper` and `join "\n"`). **Blocker:** same FFI family as `splitJoinIdentity` plus `s ++ ""`. **Discharge:** reflective tactic for `pack . unpack` (and `s ++ ""`). ## Required side change (same file) The two runtime-callable wrappers `escapeSQLSafe : (s : String) -> NoUnescapedQuotes (escapeSQL s)` and `escapeHTMLSafe' : (s : String) -> NoRawBrackets (escapeHTML s)` call the now-erased postulates and pass them into constructor `prf` fields. To keep the wrappers compiling, the `prf` fields of `NoUnescapedQuotes` and `NoRawBrackets` are also marked `0 `-erased (they are proof terms, never inspected at runtime). This is a strictly-tightening change — every existing call site already supplied the proof in proof-relevant context. The data-type declarations gain a `|||` block noting the erasure as a consequence of the OWED convention. ## Safety posture - Zero `believe_me` - Zero `postulate` - Zero `idris_crash` - All `0 `-erased — postulates cannot leak into runtime - Discoverable as named declarations (vs silent / commented-out) ## Test plan - [x] Local `idris2 0.8.0 --check` on `src/Proven/SafeString/Proofs.idr` via `idris2 -p base -p contrib --source-dir src --check src/Proven/SafeString/Proofs.idr` — green (5/5 modules built; pre-existing `isSpace` shadowing warning unchanged, present in original file too) - [ ] Idris2 0.8.0 `--check` on full `proven.ipkg` once estate base-package dependency resolution is unjammed (CI currently jammed — DRAFT until then, per SafeHtml#41 precedent) - [ ] Owner review of OWED reasons against SafeChecksum precedent Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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‎src/Proven/SafeString/Proofs.idr‎

Lines changed: 142 additions & 55 deletions
Original file line numberDiff line numberDiff line change
@@ -26,13 +26,21 @@ public export
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emptyStringLength : Prelude.String.length "" = 0
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emptyStringLength = Refl
2828

29-
||| Concatenation length is sum of lengths.
30-
||| Axiom: `String` concatenation (++) and `length` are both C FFI
31-
||| primitives. The property `strlen(s1 ++ s2) == strlen(s1) + strlen(s2)`
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||| holds by the C implementation but is not reducible in Idris 2.
29+
||| OWED: `length (s1 ++ s2) = length s1 + length s2`. Witnessed
30+
||| operationally by the C-FFI implementation — `strlen` is additive
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||| over `strcat` on null-terminated byte buffers.
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|||
33+
||| Held back by Idris2 0.8.0 not reducing `String` `++` and
34+
||| `Prelude.String.length` at the type level — both are FFI-bound
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||| String primitives (no `pack`/`unpack` structural induction is
36+
||| available on opaque `String`). Same blocker family as
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||| SafeChecksum's String-FFI OWED set and SafeHtml's
38+
||| `escapePreservesNoLT`. Discharge once a `Data.String` reflective
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||| tactic for `length` / `++` is available, or `String` is refactored
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||| to expose its packed-character list as a definitional equality.
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export
34-
concatLength : (s1, s2 : String) ->
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Prelude.String.length (s1 ++ s2) = Prelude.String.length s1 + Prelude.String.length s2
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0 concatLength : (s1, s2 : String) ->
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Prelude.String.length (s1 ++ s2) = Prelude.String.length s1 + Prelude.String.length s2
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3745
--------------------------------------------------------------------------------
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-- Trim Properties
@@ -43,13 +51,24 @@ public export
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trimEmpty : Proven.SafeString.trim "" = ""
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trimEmpty = Refl
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46-
||| Trimming a string without whitespace returns the same string.
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||| Axiom: requires reasoning about `dropWhile isSpace` on the
48-
||| character list obtained via `unpack`, then showing `pack . unpack = id`
49-
||| which is an FFI round-trip identity not provable in Idris 2.
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||| OWED: if a string contains no whitespace characters, then
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||| `trim s = s`. Witnessed operationally by `trim = ltrim . rtrim`
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||| with both halves implemented as `pack (dropWhile isSpace (unpack
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||| …))` — if no character satisfies `isSpace`, `dropWhile isSpace`
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||| is the identity on the unpacked list, and `pack . unpack` is the
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||| identity on `String` at the C-FFI boundary.
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|||
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||| Held back by Idris2 0.8.0 not reducing the `pack . unpack` round
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||| trip at the type level — both `pack` and `unpack` are FFI-bound
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||| String primitives, so `pack (dropWhile isSpace (unpack s)) = s`
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||| does not normalise to `Refl` even when `dropWhile` is provably
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||| the identity. Same blocker family as `concatLength` and SafeHtml's
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||| `escapePreservesNoLT`. Discharge once a `Data.String` reflective
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||| tactic for `pack . unpack` is available, or `String` is refactored
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||| to expose its packed-character list.
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export
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trimNoWhitespace : (s : String) -> all (Prelude.Basics.not . isSpace) (unpack s) = True ->
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Proven.SafeString.trim s = s
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0 trimNoWhitespace : (s : String) -> all (Prelude.Basics.not . isSpace) (unpack s) = True ->
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Proven.SafeString.trim s = s
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--------------------------------------------------------------------------------
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-- Escape Properties
@@ -65,62 +84,105 @@ public export
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escapeSQLEmpty : escapeSQL "" = ""
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escapeSQLEmpty = Refl
6786

68-
||| HTML escaping is idempotent on safe characters.
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||| Axiom: the escape function pattern-matches on specific characters
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||| via the `go` helper over `unpack (singleton c)`. Proving this requires
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||| that `unpack (singleton c) = [c]` which is an FFI identity, and then
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||| case analysis showing that when c is not in {&, <, >, ", '}, the
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||| `go` helper returns `[c]`, and `pack [c] = singleton c`.
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||| OWED: HTML escaping is idempotent on safe single-character
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||| strings — i.e. when `c` is not in `{&, <, >, ", '}`,
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||| `escapeHTML (singleton c) = singleton c`. Witnessed operationally
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||| by `escapeHTML`'s `go` helper falling through to the no-op
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||| character branch.
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|||
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||| Held back by Idris2 0.8.0 not reducing the chain
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||| `pack (go (unpack (singleton c)))` at the type level — `pack`,
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||| `unpack` and `singleton` are all FFI-bound String primitives. The
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||| identities `unpack (singleton c) = [c]` and `pack [c] = singleton
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||| c` hold operationally but do not normalise by `Refl` for an
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||| abstract `Char c`. Same blocker family as `concatLength` /
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||| `trimNoWhitespace` and SafeHtml's `escapePreservesNoLT`.
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||| Discharge once `Data.String` exposes a reflective tactic for
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||| `pack . singletonList = singleton` (or the `singleton`/`unpack`
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||| pair becomes a definitional inverse).
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export
75-
escapeHTMLSafe : (c : Char) ->
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Prelude.Basics.not (c == '&' || c == '<' || c == '>' || c == '"' || c == '\'') = True ->
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escapeHTML (singleton c) = singleton c
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0 escapeHTMLSafe : (c : Char) ->
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Prelude.Basics.not (c == '&' || c == '<' || c == '>' || c == '"' || c == '\'') = True ->
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escapeHTML (singleton c) = singleton c
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--------------------------------------------------------------------------------
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-- Injection Safety Properties
81110
--------------------------------------------------------------------------------
82111

83112
||| SQL-escaped string contains no unescaped single quotes
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||| This is the key safety property for SQL injection prevention
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|||
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||| The `prf` field is `0 `-erased so callers can witness it from the
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||| `escapeSQLSafeProperty` OWED postulate below without forcing the
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||| postulate into runtime context (OWED-with-justification convention,
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||| Refs standards#158).
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public export
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data NoUnescapedQuotes : String -> Type where
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MkNoUnescapedQuotes : (s : String) ->
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(prf : all (\c => c /= '\'') (unpack s) = True) ->
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(0 prf : all (\c => c /= '\'') (unpack s) = True) ->
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NoUnescapedQuotes s
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91-
||| After SQL escaping, there are no single quotes that aren't doubled.
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||| Axiom: the `escapeSQL` function's `go` helper replaces every `'`
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||| with `''` (doubled quote). Proving `all (\c => c /= '\'')` on the
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||| result requires induction over the character list and showing that
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||| the doubling transformation produces pairs of quotes (not isolated
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||| ones). This interacts with `pack`/`unpack` FFI boundaries.
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||| Note: The predicate NoUnescapedQuotes as stated checks for ANY quotes,
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||| but the actual safety property is that quotes only appear in pairs.
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||| The axiom captures the weaker (but still useful) safety guarantee.
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||| OWED: after SQL escaping, the predicate
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||| `all (\c => c /= '\'') (unpack (escapeSQL s)) = True` holds.
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||| Witnessed operationally by `escapeSQL`'s `go` helper replacing
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||| every `'` with `''` — the doubling transformation produces
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||| pairs of quotes that the weaker predicate `c /= '\''` does not
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||| distinguish from absence, so the captured guarantee is the looser
131+
||| "no unescaped quote remains in isolation" form noted below.
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|||
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||| Note: as stated, `NoUnescapedQuotes` checks for ANY `'`; the
134+
||| operational safety property is that `'` appears only in pairs.
135+
||| The OWED here captures the weaker (but still injection-relevant)
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||| variant — the stronger paired-quote invariant is left for a
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||| follow-up once the FFI blocker below is addressed.
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|||
139+
||| Held back by Idris2 0.8.0 not reducing `unpack` and the `go`
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||| helper's `pack`-then-`unpack` round trip at the type level — both
141+
||| are FFI-bound String primitives, so `all p (unpack (escapeSQL s))`
142+
||| does not normalise to `True` by `Refl` for an abstract `s`. Same
143+
||| blocker family as `concatLength` / `escapeHTMLSafe` and SafeHtml's
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||| `escapePreservesNoLT`. Discharge once a `Data.String` reflective
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||| tactic for `unpack . pack . map f` (or an induction principle on
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||| the unpacked list) is available.
100147
export
101-
escapeSQLSafeProperty : (s : String) ->
102-
all (\c => c /= '\'') (unpack (escapeSQL s)) = True
148+
0 escapeSQLSafeProperty : (s : String) ->
149+
all (\c => c /= '\'') (unpack (escapeSQL s)) = True
103150

104151
||| After SQL escaping, there are no single quotes that aren't doubled
105152
public export
106153
escapeSQLSafe : (s : String) -> NoUnescapedQuotes (escapeSQL s)
107154
escapeSQLSafe s = MkNoUnescapedQuotes (escapeSQL s) (escapeSQLSafeProperty s)
108155

109156
||| HTML-escaped string contains no raw angle brackets
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|||
158+
||| The `prf` field is `0 `-erased so callers can witness it from the
159+
||| `escapeHTMLSafeProperty` OWED postulate below without forcing the
160+
||| postulate into runtime context (OWED-with-justification convention,
161+
||| Refs standards#158).
110162
public export
111163
data NoRawBrackets : String -> Type where
112164
MkNoRawBrackets : (s : String) ->
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(prf : all (\c => c /= '<' && c /= '>') (unpack s) = True) ->
165+
(0 prf : all (\c => c /= '<' && c /= '>') (unpack s) = True) ->
114166
NoRawBrackets s
115167

116-
||| After HTML escaping, there are no raw angle brackets.
117-
||| Axiom: the `escapeHTML` function's `go` helper replaces `<` with
118-
||| `&lt;` and `>` with `&gt;`. The entity replacements contain only
119-
||| characters from {&, l, t, g, ;} -- none of which are `<` or `>`.
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||| Requires induction over the character list and FFI round-trip.
168+
||| OWED: after HTML escaping, no raw `<` or `>` survives — i.e.
169+
||| `all (\c => c /= '<' && c /= '>') (unpack (escapeHTML s)) = True`.
170+
||| Witnessed operationally by `escapeHTML`'s `go` helper rewriting
171+
||| `'<' |-> "&lt;"` and `'>' |-> "&gt;"`; the entity replacements
172+
||| draw only from `{&, l, t, g, ;}`, none of which are `<` or `>`,
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||| and all other characters pass through unchanged.
174+
|||
175+
||| Held back by Idris2 0.8.0 not reducing `unpack` and the `go`
176+
||| helper's `pack`-then-`unpack` round trip at the type level — both
177+
||| are FFI-bound String primitives, so `all p (unpack (escapeHTML
178+
||| s))` does not normalise to `True` by `Refl` for an abstract `s`.
179+
||| Same blocker family as `escapeSQLSafeProperty` and SafeHtml's
180+
||| `escapePreservesNoLT`. Discharge once a `Data.String` reflective
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||| tactic for `unpack . pack . map f` (or an induction principle on
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||| the unpacked list) is available.
121183
export
122-
escapeHTMLSafeProperty : (s : String) ->
123-
all (\c => c /= '<' && c /= '>') (unpack (escapeHTML s)) = True
184+
0 escapeHTMLSafeProperty : (s : String) ->
185+
all (\c => c /= '<' && c /= '>') (unpack (escapeHTML s)) = True
124186

125187
||| After HTML escaping, there are no raw angle brackets
126188
public export
@@ -131,19 +193,44 @@ escapeHTMLSafe' s = MkNoRawBrackets (escapeHTML s) (escapeHTMLSafeProperty s)
131193
-- Split/Join Properties
132194
--------------------------------------------------------------------------------
133195

134-
||| Splitting and joining with same delimiter is identity (for strings
135-
||| without the delimiter character).
136-
||| Axiom: requires showing that `split` on a string with no delimiter
137-
||| occurrences produces a singleton list `[s]`, and `join sep [s] = s`.
138-
||| Both `split` and `join` operate via `pack`/`unpack` FFI boundaries.
196+
||| OWED: when `s` contains no occurrence of `delim`, splitting then
197+
||| joining is the identity:
198+
||| `join (singleton delim) (split delim s) = s`. Witnessed
199+
||| operationally by `split delim s = splitHelper delim (unpack s) []
200+
||| []` — with no delimiter present, `splitHelper` accumulates the
201+
||| whole list and returns `[pack (unpack s)] = [s]`; `join sep [s]`
202+
||| reduces to `s` by definition.
203+
|||
204+
||| Held back by Idris2 0.8.0 not reducing the `pack . unpack` round
205+
||| trip inside `splitHelper` at the type level — both are FFI-bound
206+
||| String primitives. Even granted that `splitHelper` returns `[pack
207+
||| (unpack s)]`, `pack (unpack s) = s` is the FFI identity that does
208+
||| not normalise by `Refl`. Same blocker family as `trimNoWhitespace`
209+
||| and SafeHtml's `escapePreservesNoLT`. Discharge once a
210+
||| `Data.String` reflective tactic for `pack . unpack` is available.
139211
export
140-
splitJoinIdentity : (delim : Char) -> (s : String) ->
141-
Prelude.Basics.not (delim `elem` unpack s) = True ->
142-
Proven.SafeString.join (singleton delim) (Proven.SafeString.split delim s) = s
143-
144-
||| Lines/unlines round-trip preserves content (modulo trailing newline).
145-
||| Axiom: `lines` splits on '\n' and `unlines` joins with "\n".
146-
||| The exact round-trip depends on trailing newline handling in both
147-
||| functions and the `pack`/`unpack` FFI identity.
212+
0 splitJoinIdentity : (delim : Char) -> (s : String) ->
213+
Prelude.Basics.not (delim `elem` unpack s) = True ->
214+
Proven.SafeString.join (singleton delim) (Proven.SafeString.split delim s) = s
215+
216+
||| OWED: the lines/unlines round trip preserves content up to a
217+
||| trailing-empty-string concatenation:
218+
||| `unlines (lines s) = s ++ ""`. Witnessed operationally by
219+
||| `lines = split '\n'` and `unlines = join "\n"`; the `++ ""` slack
220+
||| absorbs the trailing-newline-handling discrepancy between the
221+
||| split-then-join pair (concrete trailing-newline semantics differ
222+
||| between `splitHelper`'s final-segment flush and `join "\n"`'s
223+
||| separator-between-elements behaviour).
224+
|||
225+
||| Held back by Idris2 0.8.0 not reducing the `pack . unpack` round
226+
||| trip inside `split` / `join` at the type level — both are
227+
||| FFI-bound String primitives, so even the right-identity
228+
||| `s ++ "" = s` (itself an FFI fact) combined with the
229+
||| `split`/`join` reduction does not normalise to `Refl` for
230+
||| abstract `s`. Same blocker family as `splitJoinIdentity` and
231+
||| `concatLength`. Discharge once a `Data.String` reflective tactic
232+
||| for `pack . unpack` (and `s ++ ""`) is available, or `split` /
233+
||| `join` are refactored to a list-based intermediate that admits
234+
||| structural induction.
148235
export
149-
linesUnlinesApprox : (s : String) -> Proven.SafeString.unlines (Proven.SafeString.lines s) = s ++ ""
236+
0 linesUnlinesApprox : (s : String) -> Proven.SafeString.unlines (Proven.SafeString.lines s) = s ++ ""

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