Merge pull request #224 from fiddlerwoaroof/wave/tt22-no-legacy-json

.improv is the only native format: remove the legacy JSON document loader (improvise-tt22)

Cargo.lock

@@ -897,7 +897,6 @@ dependencies = [
  "pest_derive",
  "pest_meta",
  "proptest",
- "serde",
 ]
 
 [[package]]
@@ -997,8 +996,6 @@ checksum = "cc4e190f5d26ca7051642629da2c52fc03bde85a03197c99408dcd291734c855"
 dependencies = [
  "equivalent",
  "hashbrown 0.17.1",
- "serde",
- "serde_core",
 ]
 
 [[package]]

Cargo.toml

@@ -45,7 +45,7 @@ serde = { version = "1", features = ["derive"] }
 serde_json = { version = "1", features = ["float_roundtrip"] }
 anyhow = "1"
 thiserror = "2"
-indexmap = { version = "2", features = ["serde"] }
+indexmap = "2"
 chrono = { version = "0.4", features = ["serde"] }
 flate2 = "1"
 unicode-width = "^0.2"

README.md

@@ -169,8 +169,9 @@ Measure: column
 format: ,.2f
 ```
 
-Gzip-compressed `.improv.gz` is also supported. Legacy JSON is auto-detected
-for backward compatibility.
+Gzip-compressed `.improv.gz` is also supported. `.improv` text is the only
+native document format: the old JSON document format is no longer read, and
+opening one fails with an error that says so. JSON *import* is unaffected.
 
 ## Import and scripting
 

context/code/formula-and-io.md

@@ -471,8 +471,46 @@ document that decompressed perfectly well. Decoding once, afterwards, also
 leaves **one** answer to "is this UTF-8" rather than one per branch.
 
 The `.gz` suffix selects gzip regardless of backend: that is a property of the
-document name, not of the filesystem (improvise-6mq). Legacy JSON is detected by
-a leading `{` and is never written.
+document name, not of the filesystem (improvise-6mq).
+
+**`.improv` text is the only native format (improvise-tt22).** A legacy JSON
+workbook used to be detected by a leading `{` and loaded read-only through
+`Workbook`'s serde derives. That path is gone, on the user's direction on PR #210.
+A document that still starts with `{` is refused with an error that names the
+format and says it is no longer supported. The test is
+`a_legacy_json_workbook_is_refused_by_name`. The error is decided rather than
+defaulted, because otherwise `parse_md` would report a grammar error at line 1,
+which diagnoses the wrong thing: the file is not malformed `.improv`. The check
+is on the decompressed text, so `.improv.gz` is covered too.
+
+The serde derives that existed only for that path went with it: `Workbook`,
+`Model`, `View`, `Category`, `Item`, `Group`, `CategoryKind`, `CellKey`,
+`DataStore`'s manual impls and the formula AST. So did indexmap's `serde` feature
+in `improvise-core`, `improvise-io` and the root crate, and `improvise-formula`'s
+serde dependency. Each was removed and the whole workspace rebuilt, so the
+compiler named every other consumer. Two remain, and both are the wire:
+`Axis` (whose `rename_all = "lowercase"` is its wire spelling) and `PageAxis`.
+`CellValue` was never a candidate, since it is carried on the wire too. JSON
+*import* (`StartImportWizard`, `ImportJsonHeadless`) is a separate feature and is
+untouched.
+
+One test consumer had to move: the effect-classification tests fingerprinted the
+model and the views through `serde_json`. They now use `Debug`. `format_md` was
+rejected as the replacement, because it skips the virtual views and sorts the
+data, so it would have been a weaker fingerprint.
+
+The first version of this paragraph said `Debug` was "no weaker" because it
+renders every field, including the derived `formula_cache` the JSON skipped.
+**That was wrong (improvise-pc3b).** A derived `Debug` prints a `HashMap` in hash
+order, and `recompute_formulas` clears and refills the cache. So a correct
+`ViewOnly` effect such as `RebuildLayout` changed the fingerprint in 90 of 200
+runs. The suite passed only because the fixture had no formulas, so the cache
+was empty. `Model` now has a hand-written `Debug` that renders `formula_cache`
+and `measure_agg` in key order. The fingerprint keeps every field, including the
+derived one, and a refill in a different hash order is no longer read as a
+change. `recomputing_formulas_leaves_the_model_fingerprint_alone` pins this.
+`view_only_effects_leave_shared_state_alone` now runs over a formula-bearing
+fixture, for the same reason.
 
 `parse_number_cell` returns `CellValue::Error` naming the offending text rather
 than a fabricated `0.0`. No token the current grammar admits actually fails

context/code/protocol.md

@@ -846,7 +846,7 @@ others to inherit it works in `cargo test` and nowhere else.
 **Why "can parse" and not "parses a frame".** The first version of the rule
 covered only the three crates that parse frames and listed them by hand.
 Frames are not the only place a user's number crosses a JSON parser.
-`improvise-io`'s legacy-JSON `.improv` load, `improvise-command`'s JSON import
+`improvise-io`'s legacy-JSON `.improv` load (removed since, improvise-tt22), `improvise-command`'s JSON import
 (`StartImportWizard`, `ImportJsonHeadless`) and the root binary's
 `improvise import` all parsed with the lossy default, and in the TUI binary
 nothing enabled the feature (improvise-6yvg, reproduced: `0.24815714285714285`

context/test-evidence/command.md

@@ -5880,6 +5880,33 @@ that is deliberate. Its helpers seed a client *after* mutating the host (mode,
 buffers, cursor), so a `Snapshot` would drop exactly the state those tests
 stage. This test is what makes the copy faithful at startup.
 
+
+### ui::effect::tests::recomputing_formulas_leaves_the_model_fingerprint_alone
+
+improvise-pc3b, found by the review of PR #224 at `e62a289`. That PR moved the
+effect-classification fingerprints from `serde_json` to `Debug`. The derived
+`Debug` for `Model` prints `formula_cache`, a `HashMap` that `recompute_formulas`
+clears and refills, so it prints in hash order. The reviewer measured a correct
+`ViewOnly` effect (`RebuildLayout`) changing the fingerprint in 90 of 200 runs
+once formulas were present. `test_app` has none, so the suite was green over a
+latent flake.
+
+The test builds `formula_app` (two measures across a 2×2 grid, plus
+`Profit = Revenue - Cost` and `Margin = Profit / Revenue`) 32 times. Each build
+is a fresh `App`, so each gets fresh hash states. Each time, it asserts that
+`RebuildLayout` leaves `model_fingerprint` unchanged. One flip in about two makes
+32 independent tries fail near-certainly.
+
+**Red before the fix**: the two renderings differed only in `formula_cache`'s
+entry order. The fix is a hand-written `Debug` for `Model` that renders
+`formula_cache` and `measure_agg` in key order.
+
+**Rival, run:** keep the hand-written `Debug` but print `&self.formula_cache`
+unsorted. This test fails. `view_only_effects_leave_shared_state_alone` now runs
+over `formula_app` too, so every `ViewOnly` case is checked against a populated
+cache. The two earlier injections (a `SetStatus` that writes the model, and one
+that writes a view's `number_format`) still fail it.
+
 ### a_document_opening_on_a_records_view_opens_the_host_in_records_normal
 
 improvise-y5eo. `App::with_storage` set `view_state.mode` to `Normal` and never

context/test-evidence/core.md

@@ -476,12 +476,6 @@ cell in the row).
 The pair `live_records` yields is not two facts that could drift apart: the
 surrogate is the record's own, so it is the one that resolves it back.
 
-### a_deserialized_store_can_resolve_its_records
-
-The record index is derived state and is `#[serde(skip)]`-equivalent — it must
-come back *with* the data, rebuilt through `set`, rather than being written
-alongside it.
-
 ## `model/record.rs`
 
 ### a_records_surrogate_is_pinned_to_a_literal

context/test-evidence/formula-and-io.md

@@ -1435,16 +1435,34 @@ reintroduce the iot6 divergence between what the user sees and what they export.
 On the pre-6qet tree the body is empty (the group had no row, and pruning left
 nothing), so the test fails there.
 
-## Legacy JSON numbers (improvise-6yvg)
+## Legacy JSON documents (improvise-6yvg, improvise-tt22)
 
-### `a_legacy_json_workbook_loads_its_numbers_bit_for_bit`
+`a_legacy_json_workbook_loads_its_numbers_bit_for_bit` (improvise-6yvg) pinned
+that the legacy JSON load path read numbers exactly. improvise-tt22 removed that
+path, so the test went with it. Its other role was to witness `improvise-io`'s own
+`float_roundtrip` declaration. The manifest rule in
+`every_crate_that_can_parse_json_enables_float_roundtrip` (`tests/json_numbers.rs`)
+still covers that, because `improvise-io` keeps a normal `serde_json`
+dependency for its import types (`context/test-evidence/tooling.md`).
 
-A workbook with Food/Jan holding `0.24815714285714285` is serialized with
-`serde_json` and loaded through `load_from`. A leading `{` sends it down the
-legacy JSON path. The test first asserts that the text holds the exact decimal,
-so what it measures is the parse. It compares `f64::to_bits`. Found by the
-review of PR #190, not by the ticket.
+### `a_legacy_json_workbook_is_refused_by_name`
 
-**Red at `1158c23`** in `cargo test -p improvise-io`: loaded
-`0.24815714285714283`. Green once `improvise-io`'s own manifest enables
-`float_roundtrip`, and red again with only that line reverted.
+improvise-tt22, on the user's direction on PR #210: `.improv` text is the only
+native format. A document starting with `{` used to be deserialized as a
+`Workbook`. The test writes a JSON workbook in the shape the old loader read,
+both plain and gzipped, and asserts the error names "legacy JSON" and says "no
+longer supported".
+
+**Red at `52c6a05`**: `Failed to deserialize workbook: missing field
+`next_category_id``. That is a parse error, which is exactly what the ticket said
+the refusal must not be. A complete legacy document instead loaded successfully,
+which the since-deleted bit-for-bit test above demonstrated.
+
+**Rivals, each run:**
+
+- **Deleting the refusal.** The text falls through to `parse_md`, and the test
+  fails on `legacy.improv` with "Parse error at line 1, column 1 (expected
+  version_line)". A parse error does not name the format.
+- **Refusing only when the path is not gzipped.** The plain case passes and the
+  test fails on `legacy.improv.gz` with the same grammar error. So the gzip
+  case is what makes the check prove it runs on decompressed text.

context/test-evidence/tooling.md

@@ -696,8 +696,9 @@ every target-specific entry, whose **normal** serde_json dependency lacks
 **Faults injected, each run:**
 
 - **The feature removed from `improvise-io` alone.** The check fails naming
-  `improvise-io (all targets)`, and so does
-  `a_legacy_json_workbook_loads_its_numbers_bit_for_bit`.
+  `improvise-io (all targets)`. So did
+  `a_legacy_json_workbook_loads_its_numbers_bit_for_bit`, until improvise-tt22
+  removed the legacy load path and that test with it.
   `a_json_import_stores_its_numbers_bit_for_bit` stays green, because
   `improvise-command` enables the feature and unification reaches io in its
   build.

crates/improvise-command/src/ui/effect.rs

@@ -1401,16 +1401,67 @@ mod tests {
 
     // ── Effect classification (improvise-mae) ───────────────────────────
 
-    /// Serialized model data — everything a connected client renders.
-    /// Excludes the view slice, which is per-client.
+    /// Every field of the model, rendered — everything a connected client
+    /// renders. `Debug`, not serde: the model has no serde form (improvise-tt22).
     fn model_fingerprint(app: &App) -> String {
-        serde_json::to_string(&app.model_state.workbook.model).expect("model serializes")
+        format!("{:?}", app.model_state.workbook.model)
     }
 
-    /// Serialized view configuration. Kept for the NEGATIVE arm only, where a
+    /// Every field of every view. Kept for the NEGATIVE arm only, where a
     /// hash stricter than `document_config` is wanted (improvise-1xf4).
     fn view_config_fingerprint(app: &App) -> String {
-        serde_json::to_string(&app.model_state.workbook.views).expect("views serialize")
+        format!("{:?}", app.model_state.workbook.views)
+    }
+
+    /// `test_app` plus measures, data and two chained formulas, so the derived
+    /// formula cache holds several entries for a recompute to refill.
+    fn formula_app() -> App {
+        let mut app = test_app();
+        let wb = &mut app.model_state.workbook;
+        for m in ["Revenue", "Cost"] {
+            wb.add_item("_Measure", m).unwrap();
+        }
+        let mut n = 1.0;
+        for t in ["Food", "Clothing"] {
+            for mo in ["Jan", "Feb"] {
+                for (m, scale) in [("Revenue", 10.0), ("Cost", 3.0)] {
+                    let key = CellKey::new(vec![
+                        ("Type".into(), t.into()),
+                        ("Month".into(), mo.into()),
+                        ("_Measure".into(), m.into()),
+                    ]);
+                    wb.model.set_cell(key, CellValue::Number(n * scale));
+                }
+                n += 1.0;
+            }
+        }
+        for raw in ["Profit = Revenue - Cost", "Margin = Profit / Revenue"] {
+            AddFormula {
+                raw: raw.into(),
+                target_category: "_Measure".into(),
+            }
+            .apply(&mut app);
+        }
+        app.rebuild_layout();
+        app
+    }
+
+    /// improvise-pc3b: the fingerprint must not read a derived cache's hash
+    /// order. Evidence: `context/test-evidence/command.md`.
+    #[test]
+    fn recomputing_formulas_leaves_the_model_fingerprint_alone() {
+        // Each App gets fresh hash states; one run observed ~45% flips, so 32
+        // independent tries make a hash-ordered fingerprint fail near-certainly.
+        for _ in 0..32 {
+            let mut app = formula_app();
+            let before = model_fingerprint(&app);
+            RebuildLayout.apply(&mut app);
+            assert_eq!(
+                model_fingerprint(&app),
+                before,
+                "a ViewOnly recompute changed the model fingerprint"
+            );
+        }
     }
 
     /// improvise-mae: rather than restate each declaration, apply the effect and
@@ -1450,7 +1501,8 @@ mod tests {
                 EffectKind::ViewOnly,
                 "{effect:?} is in the ViewOnly case list"
             );
-            let mut app = test_app();
+            // With formulas, so `RebuildLayout` refills a non-empty cache (pc3b).
+            let mut app = formula_app();
             let model_before = model_fingerprint(&app);
             let views_before = view_config_fingerprint(&app);
             effect.apply(&mut app);

crates/improvise-core/Cargo.toml

@@ -9,7 +9,7 @@ repository = "https://github.com/fiddlerwoaroof/improvise"
 [dependencies]
 improvise-formula = { path = "../improvise-formula" }
 anyhow = "1"
-indexmap = { version = "2", features = ["serde"] }
+indexmap = "2"
 serde = { version = "1", features = ["derive"] }
 # SipHash-2-4 under a constant key: the record surrogate must not move
 # between processes, which rules out anything built on `RandomState`

crates/improvise-core/src/model/category.rs

@@ -1,10 +1,9 @@
 use indexmap::IndexMap;
-use serde::{Deserialize, Serialize};
 
 pub type CategoryId = usize;
 pub type ItemId = usize;
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone)]
 pub struct Item {
     pub id: ItemId,
     pub name: String,
@@ -27,7 +26,7 @@ impl Item {
     }
 }
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone)]
 pub struct Group {
     pub name: String,
     /// Parent group name for nested hierarchies
@@ -50,7 +49,7 @@ impl Group {
 
 /// Regular categories store their items explicitly; virtual ones are
 /// synthesized at query time by the layout layer. context/code/core.md §9.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize, Default)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
 pub enum CategoryKind {
     #[default]
     Regular,
@@ -125,7 +124,7 @@ impl CategoryKind {
     }
 }
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone)]
 pub struct Category {
     pub id: CategoryId,
     pub name: String,
@@ -136,7 +135,6 @@ pub struct Category {
     /// Next item id counter
     next_item_id: ItemId,
     /// Whether this is a regular or virtual category
-    #[serde(default)]
     pub kind: CategoryKind,
 }
 

crates/improvise-core/src/model/cell.rs

@@ -7,7 +7,7 @@ use super::symbol::{Symbol, SymbolTable};
 
 /// A cell key: (category, item) pairs, always sorted by category name. The
 /// constructors are the only way to build one — context/code/core.md §1.
-#[derive(Debug, Clone, PartialEq, Eq, Hash, Serialize, Deserialize)]
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct CellKey(pub Vec<(String, String)>);
 
 impl CellKey {
@@ -194,8 +194,6 @@ impl RecordEntry {
     }
 }
 
-/// Serialized as a list of (key, value) pairs, so `CellKey` need not
-/// serialize as a string for JSON object keys.
 #[derive(Debug, Clone, Default)]
 pub struct DataStore {
     /// Primary storage: interned keys, insertion-ordered so records mode can
@@ -210,29 +208,6 @@ pub struct DataStore {
     records: HashMap<RecordHash, RecordEntry>,
 }
 
-impl Serialize for DataStore {
-    fn serialize<S: serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> {
-        use serde::ser::SerializeSeq;
-        let mut seq = s.serialize_seq(Some(self.cells.len()))?;
-        for (k, v) in &self.cells {
-            let cell_key = self.to_cell_key(k);
-            seq.serialize_element(&(cell_key, v))?;
-        }
-        seq.end()
-    }
-}
-
-impl<'de> Deserialize<'de> for DataStore {
-    fn deserialize<D: serde::Deserializer<'de>>(d: D) -> Result<Self, D::Error> {
-        let pairs: Vec<(CellKey, CellValue)> = Vec::deserialize(d)?;
-        let mut store = DataStore::default();
-        for (key, value) in pairs {
-            store.set(key, value);
-        }
-        Ok(store)
-    }
-}
-
 impl DataStore {
     pub fn new() -> Self {
         Self::default()
@@ -1181,15 +1156,4 @@ mod record_index {
             assert_eq!(store.resolve_record(hash), Some(record));
         }
     }
-
-    /// Derived state must come back *with* the data, rebuilt through `set`,
-    /// rather than be written alongside it.
-    #[test]
-    fn a_deserialized_store_can_resolve_its_records() {
-        let json = serde_json::to_string(&store()).expect("serializes");
-        let back: DataStore = serde_json::from_str(&json).expect("deserializes");
-        let east = key(&[("Product", "Shirts"), ("Region", "East")]);
-        assert_eq!(back.resolve_record(RecordHash::of(&east)), Some(&east));
-        assert_eq!(back.live_records().count(), 2);
-    }
 }

crates/improvise-core/src/model/types.rs

@@ -2,7 +2,6 @@ use std::collections::HashMap;
 
 use anyhow::{Result, anyhow};
 use indexmap::{IndexMap, IndexSet};
-use serde::{Deserialize, Serialize};
 
 use super::category::{Category, CategoryId, CategoryKind, MEASURE_CATEGORY};
 use super::cell::{CellKey, CellValue, DataStore};
@@ -300,7 +299,7 @@ impl Aggregation {
 
 /// Pure-data document model: categories, cells, formulas. It knows nothing
 /// about views — see [`crate::workbook::Workbook`] and core.md §10.
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Clone)]
 pub struct Model {
     pub name: String,
     pub categories: IndexMap<String, Category>,
@@ -309,13 +308,31 @@ pub struct Model {
     next_category_id: CategoryId,
     /// Per-measure aggregation, used when collapsing `Axis::None`
     /// categories. Defaults to `Sum`.
-    #[serde(default)]
     pub measure_agg: HashMap<String, AggFunc>,
     /// Cached formula evaluation results. Recomputed by `recompute_formulas`.
-    #[serde(skip)]
     formula_cache: HashMap<CellKey, CellValue>,
 }
 
+/// Every field, with the two `HashMap`s in key order: a recompute refills the
+/// cache in hash order, which is not a change (improvise-pc3b, gotcha 18).
+impl std::fmt::Debug for Model {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let mut aggs: Vec<_> = self.measure_agg.iter().collect();
+        aggs.sort_by(|a, b| a.0.cmp(b.0));
+        let mut cache: Vec<_> = self.formula_cache.iter().collect();
+        cache.sort_by(|a, b| a.0.0.cmp(&b.0.0));
+        f.debug_struct("Model")
+            .field("name", &self.name)
+            .field("categories", &self.categories)
+            .field("data", &self.data)
+            .field("formulas", &self.formulas)
+            .field("next_category_id", &self.next_category_id)
+            .field("measure_agg", &aggs)
+            .field("formula_cache", &cache)
+            .finish()
+    }
+}
+
 impl Model {
     pub fn new(name: impl Into<String>) -> Self {
         let name = name.into();

crates/improvise-core/src/view/types.rs

@@ -1,14 +1,9 @@
 use indexmap::IndexMap;
-use serde::{Deserialize, Serialize};
 use std::collections::{HashMap, HashSet};
 
 use super::axis::Axis;
 use crate::model::category::CategoryKind;
 
-fn default_prune() -> bool {
-    true
-}
-
 /// Scratch views the app rebuilds on demand rather than persisting, because
 /// they put the never-persisted `_Index`/`_Dim` on axes (improvise-60z).
 pub const VIRTUAL_VIEW_NAMES: [&str; 2] = ["_Records", "_Drill"];
@@ -32,7 +27,7 @@ pub fn unused_view_name<'a>(existing: impl IntoIterator<Item = &'a str>) -> Stri
         .expect("a name is free below usize::MAX, there being fewer views")
 }
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone)]
 pub struct View {
     pub name: String,
     /// Axis assignment for each category
@@ -46,7 +41,6 @@ pub struct View {
     /// Number format string (e.g. ",.0f" for comma-separated integer)
     pub number_format: String,
     /// When true, empty rows/columns are pruned from the display.
-    #[serde(default = "default_prune")]
     pub prune_empty: bool,
 }
 

crates/improvise-core/src/workbook.rs

@@ -3,13 +3,12 @@
 
 use anyhow::{Result, anyhow};
 use indexmap::IndexMap;
-use serde::{Deserialize, Serialize};
 
 use crate::model::Model;
 use crate::model::category::{CategoryId, CategoryKind, ItemId};
 use crate::view::{Axis, DEFAULT_VIEW, View};
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone)]
 pub struct Workbook {
     pub model: Model,
     pub views: IndexMap<String, View>,

crates/improvise-formula/Cargo.toml

@@ -10,7 +10,6 @@ repository = "https://github.com/fiddlerwoaroof/improvise"
 anyhow = "1"
 pest = "2.9.2"
 pest_derive = "2.9.2"
-serde = { version = "1", features = ["derive"] }
 
 [dev-dependencies]
 pest_meta = "2.9.2"

crates/improvise-formula/src/ast.rs

@@ -1,6 +1,4 @@
-use serde::{Deserialize, Serialize};
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone)]
 pub enum AggFunc {
     Sum,
     Avg,
@@ -11,7 +9,7 @@ pub enum AggFunc {
 
 /// Arithmetic and comparison operators. An enum rather than a `String`, so an
 /// invalid operator is caught at parse time — design-principles §2.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum BinOp {
     Add,
     Sub,
@@ -26,13 +24,13 @@ pub enum BinOp {
     Ge,
 }
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone)]
 pub struct Filter {
     pub category: String,
     pub item: String,
 }
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone)]
 pub enum Expr {
     Number(f64),
     Ref(String),
@@ -45,7 +43,7 @@ pub enum Expr {
     Is(Filter),
 }
 
-#[derive(Debug, Clone, Serialize, Deserialize)]
+#[derive(Debug, Clone)]
 pub struct Formula {
     /// The raw formula text, e.g. "Profit = Revenue - Cost"
     pub raw: String,
@@ -59,7 +57,6 @@ pub struct Formula {
     pub filter: Option<Filter>,
     /// How this formula's target is drawn, overriding the view's `format:` for
     /// that one measure. `None` means the view answers — `context/code/core.md`.
-    #[serde(default)]
     pub format: Option<String>,
 }
 

crates/improvise-io/Cargo.toml

@@ -13,7 +13,7 @@ anyhow = "1"
 chrono = { version = "0.4", features = ["serde"] }
 csv = "1"
 flate2 = "1"
-indexmap = { version = "2", features = ["serde"] }
+indexmap = "2"
 pest = "2.9.2"
 pest_derive = "2.9.2"
 serde = { version = "1", features = ["derive"] }

crates/improvise-io/src/persistence/mod.rs

@@ -1,4 +1,4 @@
-//! `.improv` document lifecycle — save, load, gzip, legacy JSON — over a
+//! `.improv` document lifecycle — save, load, gzip — over a
 //! [`Storage`] backend. The text format is in `format`, `parse` and `export`.
 
 mod export;
@@ -96,11 +96,16 @@ pub fn load_from(storage: &dyn Storage, path: &Path) -> Result<Workbook> {
     };
     let text =
         String::from_utf8(bytes).with_context(|| format!("{} is not UTF-8", path.display()))?;
+    // `.improv` text is the only native format; a JSON workbook is named, not
+    // handed to the grammar to fail on its first byte (improvise-tt22).
     if text.trim_start().starts_with('{') {
-        serde_json::from_str(&text).context("Failed to deserialize workbook")
-    } else {
-        parse_md(&text)
+        anyhow::bail!(
+            "{} is a legacy JSON workbook, which is no longer supported: \
+             only .improv text can be opened",
+            path.display()
+        );
     }
+    parse_md(&text)
 }
 
 pub fn autosave_path(path: &Path) -> std::path::PathBuf {
@@ -194,37 +199,34 @@ mod tests {
         );
     }
 
+    /// improvise-tt22: `.improv` text is the only native format, so a legacy
+    /// JSON workbook is refused by name. Evidence: `context/test-evidence/formula-and-io.md`.
     #[test]
-    fn load_dispatcher_detects_legacy_json_by_brace() {
-        // The load() function routes to JSON deserializer when text starts with '{'
-        let m = two_cat_model();
-        let json = serde_json::to_string_pretty(&m).unwrap();
-        assert!(json.trim_start().starts_with('{'), "sanity check");
-        // Deserialise via the JSON path
-        let m2: Workbook = serde_json::from_str(&json).unwrap();
-        assert_eq!(m2.model.name, "Budget");
-    }
-
-    #[test]
-    fn a_legacy_json_workbook_loads_its_numbers_bit_for_bit() {
+    fn a_legacy_json_workbook_is_refused_by_name() {
         use crate::storage::{MemoryFs, Storage};
-        const LOSSY: f64 = 0.248_157_142_857_142_85;
-        let key = coord(&[("Type", "Food"), ("Month", "Jan")]);
-        let mut wb = two_cat_model();
-        wb.model.set_cell(key.clone(), CellValue::Number(LOSSY));
-        let json = serde_json::to_string(&wb).unwrap();
-        assert!(
-            json.contains("0.24815714285714285"),
-            "the file holds the exact text"
-        );
-        let fs = MemoryFs::new();
-        let path = std::path::Path::new("legacy.improv");
-        fs.write(path, json.as_bytes()).unwrap();
-        let loaded = super::load_from(&fs, path).unwrap();
-        let Some(CellValue::Number(n)) = loaded.model.get_cell(&key) else {
-            panic!("the cell must load as a number");
-        };
-        assert_eq!(n.to_bits(), LOSSY.to_bits(), "loaded {n:?}, not {LOSSY:?}");
+        // The shape the removed loader read: `Workbook`'s serde form.
+        let legacy = r#"
+            {"model": {"name": "Budget", "categories": {}, "data": [], "formulas": []},
+             "views": {}, "active_view": "Default"}"#;
+        for name in ["legacy.improv", "legacy.improv.gz"] {
+            let fs = MemoryFs::new();
+            let path = std::path::Path::new(name);
+            let bytes = if name.ends_with(".gz") {
+                use std::io::Write;
+                let mut enc =
+                    flate2::write::GzEncoder::new(Vec::new(), flate2::Compression::default());
+                enc.write_all(legacy.as_bytes()).unwrap();
+                enc.finish().unwrap()
+            } else {
+                legacy.as_bytes().to_vec()
+            };
+            fs.write(path, &bytes).unwrap();
+            let err = format!("{:#}", super::load_from(&fs, path).unwrap_err());
+            assert!(
+                err.contains("legacy JSON") && err.contains("no longer supported"),
+                "{name}: expected the format named and refused, got {err:?}"
+            );
+        }
     }
 
     // ── save/load roundtrip via file ────────────────────────────────────

harness/opfs-contract/Cargo.lock

@@ -196,7 +196,6 @@ dependencies = [
  "anyhow",
  "pest",
  "pest_derive",
- "serde",
 ]
 
 [[package]]
@@ -228,8 +227,6 @@ checksum = "cc4e190f5d26ca7051642629da2c52fc03bde85a03197c99408dcd291734c855"
 dependencies = [
  "equivalent",
  "hashbrown",
- "serde",
- "serde_core",
 ]
 
 [[package]]