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+# Risk regime as a structural campaign axis — Implementation Plan
+
+> **Parent spec:** `docs/specs/risk-regime-axis.md`
+>
+> **For agentic workers:** REQUIRED SUB-SKILL: use the `implement` skill to
+> run this plan. Steps use `- [ ]` checkboxes for tracking.
+
+**Goal:** Make the protective-stop regime a first-class structural axis of the
+campaign matrix — a peer of instruments and windows — so a campaign runs every
+`(strategy, instrument, window, regime)` cell, stamps each member's resolved
+stop into its manifest, and compares regimes at presentation without ever
+argmax-selecting across them.
+
+**Architecture:** Three tiers. `aura-research` gains the serializable
+`RiskRegime` vocabulary and an optional `CampaignDoc.risk` list (absent = one
+implicit default regime, absent-serializes for content-id parity).
+`aura-campaign` (+ the `aura-registry` record it writes) expands the matrix with
+the regime as a *kept-separate* axis (peer of `window`; the nominee key gains
+the regime ordinal, so generalize aggregates across instruments *within* a
+regime, never across regimes). `aura-cli` maps `RiskRegime → StopRule` at the
+member-runner boundary, threads it through `wrap_r`'s bound-stop arm, and stamps
+it into the manifest.
+
+**Tech Stack:** Rust workspace crates `aura-research`, `aura-registry`,
+`aura-campaign`, `aura-cli`; serde; the `wrap_r` R-scaffolding; the campaign
+executor + registry.
+
+**Two bounded, documented descopes** (non-load-bearing details of the spec's
+Components/Family-naming sections, deferred as clean follow-ups):
+
+1. **Descriptive `CAMPAIGN_SECTIONS` introspection entry for `risk`.** `risk` is
+   a top-level array, not a slot-bearing section like `data`/`strategy`, so it
+   does not fit the current `BlockSchema` slot model. The load-bearing
+   *validation* (a bad regime is refused) still lands, in Task 2. Introspection
+   completeness for the regime list is a follow-up.
+2. **Multi-regime trace-directory isolation (`campaign_cell_key`).** The
+   load-bearing registry family-collision fix is the `-r{regime_ordinal}`
+   discriminator in the `family_name` (Task 3, exec.rs) — the family store keys
+   on that. `campaign_cell_key` names *trace* dirs and runs only when
+   `persist_taps` is non-empty; threading a regime through it would drag in a
+   `CellRealization.regime_ordinal` stored-format change. This cycle's E2E uses
+   `persist_taps: []`, so multi-regime trace-dir isolation is deferred.
+
+---
+
+**Files this plan creates or modifies:**
+
+- Modify: `crates/aura-research/src/lib.rs` — `RiskRegime` enum, `CampaignDoc.risk` field, `DocFault::BadRegime`, `validate_campaign` regime check, in-file tests.
+- Modify: `crates/aura-cli/src/research_docs.rs:141` — CLI phrasing for `DocFault::BadRegime`.
+- Modify: `crates/aura-registry/src/lineage.rs:158` — `CampaignGeneralization.regime_ordinal`.
+- Modify: `crates/aura-registry/src/lib.rs` — the `CampaignGeneralization` test literal.
+- Modify: `crates/aura-campaign/src/lib.rs:26` — `CellSpec.regime` + `regime_ordinal`.
+- Modify: `crates/aura-campaign/src/exec.rs` — regime expansion, 3-tuple nominee key, generalize `regime_ordinal`, family-name discriminator.
+- Modify: `crates/aura-campaign/tests/member_seam_e2e.rs:18` — `CellSpec` literal.
+- Modify: `crates/aura-campaign/tests/execute.rs` — family-id pins + new two-regime test.
+- Modify: `crates/aura-cli/src/main.rs` — `StopArm`, `wrap_r` signature, `r_sma_graph` map, `run_blueprint_member` stop param + manifest stamp + its 6 callers.
+- Modify: `crates/aura-cli/src/campaign_run.rs` — `CliMemberRunner::run_member` regime→stop map.
+- Modify: `crates/aura-cli/tests/cli_run.rs` — flip the characterization pin, extend the dissolved-contract pin, add the two-regime E2E.
+- Modify: `crates/aura-cli/src/verb_sugar.rs:76` — `risk: vec![]` in the generated doc.
+- Modify: `docs/design/INDEX.md` — the C10/C20 amendment note.
+
+---
+
+## Task 1: `RiskRegime` vocabulary + `CampaignDoc.risk` field (aura-research)
+
+**Files:**
+- Modify: `crates/aura-research/src/lib.rs`
+
+- [ ] **Step 1: Write the failing tests**
+
+Add to the `#[cfg(test)] mod` in `crates/aura-research/src/lib.rs` (the module that already holds `CAMPAIGN_FIXTURE`):
+
+```rust
+#[test]
+fn risk_regime_round_trips_as_externally_tagged_vol() {
+    let r = RiskRegime::Vol { length: 3, k: 2.0 };
+    let j = serde_json::to_string(&r).unwrap();
+    assert_eq!(j, r#"{"vol":{"length":3,"k":2.0}}"#);
+    let back: RiskRegime = serde_json::from_str(&j).unwrap();
+    assert_eq!(back, r);
+}
+
+#[test]
+fn campaign_absent_and_empty_risk_omit_from_canonical_bytes() {
+    let doc: CampaignDoc = serde_json::from_str(CAMPAIGN_FIXTURE).unwrap();
+    assert!(doc.risk.is_empty(), "an absent risk key deserializes to empty");
+    let absent = campaign_to_json(&doc);
+    assert!(!absent.contains("\"risk\""), "absent risk omits from serialization: {absent}");
+    let mut empty = doc.clone();
+    empty.risk = vec![];
+    assert_eq!(
+        content_id_of(&campaign_to_json(&empty)),
+        content_id_of(&absent),
+        "an explicit empty risk hashes identically to an absent one"
+    );
+}
+
+#[test]
+fn campaign_with_risk_serializes_and_round_trips_the_regimes() {
+    let mut doc: CampaignDoc = serde_json::from_str(CAMPAIGN_FIXTURE).unwrap();
+    doc.risk = vec![
+        RiskRegime::Vol { length: 3, k: 1.5 },
+        RiskRegime::Vol { length: 3, k: 3.0 },
+    ];
+    let out = campaign_to_json(&doc);
+    assert!(out.contains(r#""risk":[{"vol":{"length":3,"k":1.5}},{"vol":{"length":3,"k":3.0}}]"#),
+        "risk serializes in place as a tagged list: {out}");
+    let back: CampaignDoc = serde_json::from_str(&out).unwrap();
+    assert_eq!(back.risk, doc.risk);
+}
+```
+
+- [ ] **Step 2: Run the tests to verify they fail**
+
+Run: `cargo test -p aura-research risk_regime 2>&1 | tail -20`
+Expected: compile error — `cannot find type RiskRegime` / no field `risk` on `CampaignDoc`.
+
+- [ ] **Step 3: Add the `RiskRegime` enum**
+
+In `crates/aura-research/src/lib.rs`, immediately after the `Axis` type block (after the `pub struct Axis { pub kind: ScalarKind, pub values: Vec<Scalar> }` region near line 471), add:
+
+```rust
+/// A protective-stop regime: a serializable, content-addressable mirror of the
+/// runtime `StopRule` structural axis (C10/C20). The sole implemented variant is
+/// the vol-stop; the shipped fixed-stop rule is admitted as a future additive
+/// variant (it runs as a composite today but is not yet campaign-reachable).
+/// Externally tagged so adding `Fixed` is additive — no content-id churn on
+/// stored `Vol` regimes.
+#[derive(Clone, Copy, Debug, PartialEq, Serialize, Deserialize)]
+#[serde(deny_unknown_fields, rename_all = "snake_case")]
+pub enum RiskRegime {
+    Vol { length: i64, k: f64 },
+}
+```
+
+- [ ] **Step 4: Add the `CampaignDoc.risk` field**
+
+In `crates/aura-research/src/lib.rs`, in `pub struct CampaignDoc` (line 425-436), insert the `risk` field immediately after `pub data: DataSection,`:
+
+```rust
+    pub data: DataSection,
+    /// Structural risk-execution axis: the finite list of stop regimes the
+    /// matrix runs each cell under. Absent or empty = one implicit default
+    /// regime (the runtime's baked constants). Absent-serializes → content-id
+    /// parity for every risk-less document (the `description` precedent).
+    #[serde(default, skip_serializing_if = "Vec::is_empty")]
+    pub risk: Vec<RiskRegime>,
+    pub strategies: Vec<StrategyEntry>,
+```
+
+- [ ] **Step 5: Run the tests to verify they pass**
+
+(One positional filter per invocation — a multi-filter `cargo test X Y` prints nothing in this environment.)
+Run: `cargo test -p aura-research risk_regime_round_trips 2>&1 | tail -5`
+Expected: PASS (1 test).
+Run: `cargo test -p aura-research campaign_absent_and_empty_risk 2>&1 | tail -5`
+Expected: PASS (1 test).
+Run: `cargo test -p aura-research campaign_with_risk_serializes 2>&1 | tail -5`
+Expected: PASS (1 test).
+
+---
+
+## Task 2: `validate_campaign` regime refusal + CLI phrasing (aura-research + aura-cli)
+
+**Files:**
+- Modify: `crates/aura-research/src/lib.rs`
+- Modify: `crates/aura-cli/src/research_docs.rs:141`
+
+- [ ] **Step 1: Write the failing test**
+
+Add to the `#[cfg(test)] mod` in `crates/aura-research/src/lib.rs`:
+
+```rust
+#[test]
+fn validate_campaign_flags_each_non_positive_regime() {
+    let mut doc: CampaignDoc = serde_json::from_str(CAMPAIGN_FIXTURE).unwrap();
+    doc.risk = vec![
+        RiskRegime::Vol { length: 3, k: 2.0 }, // 0: valid
+        RiskRegime::Vol { length: 0, k: 2.0 }, // 1: length < 1
+        RiskRegime::Vol { length: 3, k: 0.0 }, // 2: k <= 0
+    ];
+    let faults = validate_campaign(&doc);
+    assert!(faults.contains(&DocFault::BadRegime { index: 1 }), "{faults:?}");
+    assert!(faults.contains(&DocFault::BadRegime { index: 2 }), "{faults:?}");
+    assert!(!faults.contains(&DocFault::BadRegime { index: 0 }), "valid regime not flagged: {faults:?}");
+}
+
+#[test]
+fn validate_campaign_accepts_a_valid_risk_section() {
+    let mut doc: CampaignDoc = serde_json::from_str(CAMPAIGN_FIXTURE).unwrap();
+    doc.risk = vec![RiskRegime::Vol { length: 3, k: 1.5 }];
+    assert!(validate_campaign(&doc).is_empty(), "{:?}", validate_campaign(&doc));
+}
+```
+
+- [ ] **Step 2: Run the test to verify it fails**
+
+Run: `cargo test -p aura-research validate_campaign_flags 2>&1 | tail -20`
+Expected: compile error — `no variant BadRegime on DocFault`.
+
+- [ ] **Step 3: Add the `DocFault::BadRegime` variant**
+
+In `crates/aura-research/src/lib.rs`, in `pub enum DocFault`, insert on the campaign side, immediately after `BadWindow { index: usize },` (line 658):
+
+```rust
+    BadWindow { index: usize },
+    BadRegime { index: usize },
+```
+
+- [ ] **Step 4: Add the regime check to `validate_campaign`**
+
+In `crates/aura-research/src/lib.rs`, in `pub fn validate_campaign`, insert after the windows loop closes (after line 747, the `}` that ends the `for (i, w) in doc.data.windows...` loop):
+
+```rust
+    for (i, r) in doc.risk.iter().enumerate() {
+        let RiskRegime::Vol { length, k } = r;
+        // length < 1 catches 0 and negatives; !(k > 0.0) catches k <= 0 AND NaN.
+        if *length < 1 || !(*k > 0.0) {
+            faults.push(DocFault::BadRegime { index: i });
+        }
+    }
+```
+
+- [ ] **Step 5: Add the CLI phrasing arm (cross-crate compile break — same task)**
+
+In `crates/aura-cli/src/research_docs.rs`, in the `DocFault` match, insert immediately after the `DocFault::BadWindow { index } => { ... }` arm (line 141):
+
+```rust
+        DocFault::BadRegime { index } => {
+            format!("risk regime {index} is invalid: stop length must be >= 1 and k must be > 0")
+        }
+```
+
+- [ ] **Step 6: Run the tests + the workspace build gate**
+
+Run: `cargo build -p aura-research -p aura-cli 2>&1 | tail -5`
+Expected: `Finished` — 0 errors (the `DocFault` match is exhaustive again).
+Run: `cargo test -p aura-research validate_campaign_flags 2>&1 | tail -5`
+Expected: PASS (1 test).
+Run: `cargo test -p aura-research validate_campaign_accepts_a_valid_risk 2>&1 | tail -5`
+Expected: PASS (1 test).
+
+---
+
+## Task 3: matrix regime expansion (aura-campaign + aura-registry)
+
+**Files:**
+- Modify: `crates/aura-registry/src/lineage.rs:158`
+- Modify: `crates/aura-registry/src/lib.rs` — the `CampaignGeneralization` test literal (~1852)
+- Modify: `crates/aura-campaign/src/lib.rs:26`
+- Modify: `crates/aura-campaign/src/exec.rs`
+- Modify: `crates/aura-campaign/tests/member_seam_e2e.rs:18`
+- Modify: `crates/aura-campaign/tests/execute.rs`
+
+- [ ] **Step 1: Write the failing test**
+
+Add to `crates/aura-campaign/tests/execute.rs` (modeled on `execute_sweep_only_records_family_and_selection`):
+
+```rust
+#[test]
+fn execute_runs_one_family_per_regime_with_distinct_ids() {
+    let reg = temp_registry("two_regimes");
+    let mut doc = campaign(&["EURUSD"]);
+    doc.risk = vec![
+        aura_research::RiskRegime::Vol { length: 3, k: 1.5 },
+        aura_research::RiskRegime::Vol { length: 3, k: 2.0 },
+    ];
+    let proc_doc = process(vec![sweep_stage(false)]);
+    let out = execute(CAMPAIGN_ID, &doc, &proc_doc, &strategies(), &FakeRunner::clean(), &reg)
+        .expect("two-regime campaign executes");
+
+    // one cell per regime, each with its own sweep family.
+    assert_eq!(out.cells.len(), 2, "one cell per regime");
+    let p = &CAMPAIGN_ID[..8];
+    assert_eq!(out.cells[0].families[0].family_id, format!("{p}-0-EURUSD-w0-r0-s0-0"));
+    assert_eq!(out.cells[1].families[0].family_id, format!("{p}-0-EURUSD-w0-r1-s0-0"));
+}
+```
+
+- [ ] **Step 2: Run the test to verify it fails**
+
+Run: `cargo test -p aura-campaign execute_runs_one_family_per_regime 2>&1 | tail -20`
+Expected: compile error — no field `risk` visible on the test `doc` path is fine (Task 1 shipped it), so the real failure is the assertion: `family_id` is `...-w0-s0-0` (no `-r0`) and `out.cells.len() == 1` (regimes not expanded).
+
+- [ ] **Step 3: Add `regime_ordinal` to `CampaignGeneralization` (aura-registry)**
+
+In `crates/aura-registry/src/lineage.rs`, in `pub struct CampaignGeneralization` (line 158), insert after `pub window_ordinal: usize,`:
+
+```rust
+    pub window_ordinal: usize,
+    /// The regime ordinal (0 for the default regime) — the third structural
+    /// coordinate, so a generalize grade is unambiguous per (strategy, window,
+    /// regime). `#[serde(default)]` keeps pre-feature stored records parsing.
+    #[serde(default)]
+    pub regime_ordinal: usize,
+```
+
+- [ ] **Step 4: Update the `CampaignGeneralization` test literal (aura-registry)**
+
+In `crates/aura-registry/src/lib.rs`, find the `CampaignGeneralization { ... }` literal in the tests (near line 1852) and add `regime_ordinal: 0,` after its `window_ordinal:` field.
+
+Run: `git grep -nE 'CampaignGeneralization \{' -- crates/aura-registry/src/lib.rs`
+(then edit the one literal — the `pub struct` def is in lineage.rs, not lib.rs).
+
+- [ ] **Step 5: Add the regime fields to `CellSpec` (aura-campaign)**
+
+In `crates/aura-campaign/src/lib.rs`, in `pub struct CellSpec` (line 26-37), insert after `pub window_ms: (i64, i64),`:
+
+```rust
+    pub window_ms: (i64, i64),
+    /// The cell's risk regime. `None` = the member runner's baked default (the
+    /// absent/empty-`risk` case); `Some` = an explicit document regime.
+    pub regime: Option<aura_research::RiskRegime>,
+    /// The regime's ordinal in the resolved regime list (0 for the default) —
+    /// keys the generalize unit and discriminates family names.
+    pub regime_ordinal: usize,
+```
+
+(If `aura_research::RiskRegime` is not yet imported in this file, add it to the existing `use aura_research::{...}` line.)
+
+- [ ] **Step 6: Expand the matrix over regimes in `exec.rs`**
+
+In `crates/aura-campaign/src/exec.rs`, change the nominee map type (line 124):
+
+```rust
+    // before
+    let mut nominees: BTreeMap<(usize, usize), Vec<(String, Nominee)>> = BTreeMap::new();
+    // after
+    let mut nominees: BTreeMap<(usize, usize, usize), Vec<(String, Nominee)>> = BTreeMap::new();
+```
+
+Immediately before the `for (strategy_ordinal, ...)` loop (line 125), resolve the regime list:
+
+```rust
+    // Absent/empty risk = a single default cell (regime None, ordinal 0); a
+    // non-empty list maps each regime to Some. The default's value is the member
+    // runner's — the doc is never mutated (its content id hashes with risk absent).
+    let regimes: Vec<(usize, Option<aura_research::RiskRegime>)> = if campaign.risk.is_empty() {
+        vec![(0, None)]
+    } else {
+        campaign.risk.iter().copied().enumerate().map(|(i, r)| (i, Some(r))).collect()
+    };
+```
+
+Wrap the cell build in a regime loop (innermost, inside the window loop at line 129) and thread the ordinal into the cell + nominee key:
+
+```rust
+            for (window_ordinal, window) in campaign.data.windows.iter().enumerate() {
+                for (regime_ordinal, regime) in &regimes {
+                    let cell = CellSpec {
+                        strategy_ordinal,
+                        strategy_id: strategy_id.clone(),
+                        blueprint_json: blueprint_json.clone(),
+                        axes: entry.axes.clone(),
+                        instrument: instrument.clone(),
+                        window_ms: (window.from_ms, window.to_ms),
+                        regime: *regime,
+                        regime_ordinal: *regime_ordinal,
+                    };
+                    let (outcome, realization) = run_cell(
+                        &cell, process, campaign_prefix, window_ordinal, campaign.seed, runner, registry,
+                    )?;
+                    nominees
+                        .entry((strategy_ordinal, window_ordinal, *regime_ordinal))
+                        .or_default()
+                        .push((instrument.clone(), outcome.nominee.clone()));
+                    cells_out.push(outcome);
+                    cells_rec.push(realization);
+                }
+            }
+```
+
+- [ ] **Step 7: Thread the regime ordinal through generalize**
+
+In `crates/aura-campaign/src/exec.rs`, the generalize loop (line 166) now iterates the 3-tuple key; update the destructuring and the `CampaignGeneralization` construction (line 187):
+
+```rust
+    // before
+        for ((strategy_ordinal, window_ordinal), cells) in &nominees {
+    // after
+        for ((strategy_ordinal, window_ordinal, regime_ordinal), cells) in &nominees {
+```
+
+and in the `CampaignGeneralization { ... }` literal add `regime_ordinal: *regime_ordinal,` after `window_ordinal: *window_ordinal,`.
+
+- [ ] **Step 8: Add the `-r{regime_ordinal}` family-name discriminator**
+
+In `crates/aura-campaign/src/exec.rs`, at BOTH family-name format sites (line 250 and line 352), change:
+
+```rust
+    // before
+                    "{campaign_prefix}-{}-{}-w{window_ordinal}-s{stage_ordinal}",
+                    cell.strategy_ordinal, cell.instrument,
+    // after
+                    "{campaign_prefix}-{}-{}-w{window_ordinal}-r{}-s{stage_ordinal}",
+                    cell.strategy_ordinal, cell.instrument, cell.regime_ordinal,
+```
+
+- [ ] **Step 9: Update the `CellSpec` literal in `member_seam_e2e.rs`**
+
+In `crates/aura-campaign/tests/member_seam_e2e.rs`, in `fn cell()` (line 18-26), add after `instrument: "EURUSD".to_string(),` / `window_ms: (0, 20),`:
+
+```rust
+        window_ms: (0, 20),
+        regime: None,
+        regime_ordinal: 0,
+```
+
+- [ ] **Step 10: Update the family-id pins in `execute.rs`**
+
+In `crates/aura-campaign/tests/execute.rs`, the existing tests use `campaign()` (no risk → one default regime, ordinal 0), so every family id gains exactly `-r0`. Update all three sites:
+
+```rust
+    // line 238 and line 301: before
+    let expected_family_id = format!("{}-0-EURUSD-w0-s0-0", &CAMPAIGN_ID[..8]);
+    // after
+    let expected_family_id = format!("{}-0-EURUSD-w0-r0-s0-0", &CAMPAIGN_ID[..8]);
+```
+
+```rust
+    // line 381: before
+    let base = format!("{}-0-EURUSD-w0-s0", &CAMPAIGN_ID[..8]);
+    // after
+    let base = format!("{}-0-EURUSD-w0-r0-s0", &CAMPAIGN_ID[..8]);
+```
+
+- [ ] **Step 11: Build + test gate (compile-coherent unit)**
+
+Run: `cargo build -p aura-registry -p aura-campaign 2>&1 | tail -5`
+Expected: `Finished` — 0 errors (all `CellSpec` / `CampaignGeneralization` literals threaded).
+Run: `cargo test -p aura-campaign 2>&1 | tail -15`
+Expected: PASS, including `execute_runs_one_family_per_regime_with_distinct_ids` and the updated pins.
+
+---
+
+## Task 4: the runtime binding — `StopArm`, stamp, regime→stop map (aura-cli)
+
+**Files:**
+- Modify: `crates/aura-cli/src/main.rs`
+- Modify: `crates/aura-cli/src/campaign_run.rs`
+- Modify: `crates/aura-cli/tests/cli_run.rs`
+
+- [ ] **Step 1: Flip the characterization pin + extend the dissolved-contract pin (the RED side)**
+
+In `crates/aura-cli/tests/cli_run.rs`, in `sweep_real_blueprint_member_manifest_carries_no_stop_param_today`, replace the assertion body of the `for line in &lines` loop so it now REQUIRES the default stop (the ratified additive stamp):
+
+```rust
+    for line in &lines {
+        let v: serde_json::Value = serde_json::from_str(line).expect("member line parses as JSON");
+        let params = v["report"]["manifest"]["params"]
+            .as_array()
+            .expect("manifest.params is an array");
+        let get = |name: &str| params.iter().find(|p| p[0].as_str() == Some(name));
+        assert_eq!(get("stop_length").and_then(|p| p[1]["I64"].as_i64()), Some(3),
+            "the resolved default stop length is stamped: {line}");
+        assert_eq!(get("stop_k").and_then(|p| p[1]["F64"].as_f64()), Some(2.0),
+            "the resolved default stop k is stamped: {line}");
+    }
+```
+
+Rename the test to `sweep_real_blueprint_member_manifest_stamps_the_default_stop` and update its doc comment's first sentence to: `the dissolved real-data sweep member manifest stamps its resolved stop (`stop_length`/`stop_k`) — the default regime here.`
+
+In `sweep_real_blueprint_member_lines_pin_the_dissolved_contract`, inside its `for i in 0..4` loop, after the instrument-stamp assertion (line 1471-1475), add:
+
+```rust
+        assert!(
+            params.iter().any(|p| p[0].as_str() == Some("stop_length"))
+                && params.iter().any(|p| p[0].as_str() == Some("stop_k")),
+            "the dissolved sweep stamps the resolved stop: {line}"
+        );
+```
+
+- [ ] **Step 2: Run the pins to verify they fail**
+
+Run: `cargo test -p aura-cli --test cli_run sweep_real_blueprint_member_manifest_stamps_the_default_stop 2>&1 | tail -20`
+Expected: FAIL — the manifest carries no `stop_length`/`stop_k` yet (assertion `Some(3)` gets `None`).
+
+- [ ] **Step 3: Add the `StopArm` enum**
+
+In `crates/aura-cli/src/main.rs`, immediately before `fn wrap_r(` (line 2652, above its doc comment at 2645), add:
+
+```rust
+/// The vol-stop arm `wrap_r` embeds: an OPEN stop whose two knobs land in
+/// `param_space` as sweep axes (the r-sma verb's gridded-stop path), or a BOUND
+/// stop with fixed params (a single run, a blueprint/campaign member).
+enum StopArm {
+    Open,
+    Bound(StopRule),
+}
+```
+
+- [ ] **Step 4: Change `wrap_r`'s signature and stop arm**
+
+In `crates/aura-cli/src/main.rs`, in `fn wrap_r` (line 2652-2665), change the 6th parameter:
+
+```rust
+    // before
+    stop_open: bool,
+    // after
+    stop: StopArm,
+```
+
+and the stop-arm body (line 2691-2695):
+
+```rust
+    // before
+    let exec = g.add(if stop_open {
+        risk_executor_vol_open(1.0)
+    } else {
+        risk_executor(StopRule::Vol { length: R_SMA_STOP_LENGTH, k: R_SMA_STOP_K }, 1.0)
+    });
+    // after
+    let exec = g.add(match stop {
+        StopArm::Open => risk_executor_vol_open(1.0),
+        StopArm::Bound(rule) => risk_executor(rule, 1.0),
+    });
+```
+
+- [ ] **Step 5: Map `r_sma_graph`'s bool at its `wrap_r` call**
+
+In `crates/aura-cli/src/main.rs`, in `fn r_sma_graph`, the `wrap_r(...)` call (line 2633-2642) passes `stop_open` as the 6th arg; replace that arg with the mapped `StopArm`:
+
+```rust
+    wrap_r(
+        sma_signal(fast_len, slow_len),
+        tx_eq,
+        tx_ex,
+        tx_r,
+        tx_req,
+        if stop_open {
+            StopArm::Open
+        } else {
+            StopArm::Bound(StopRule::Vol { length: R_SMA_STOP_LENGTH, k: R_SMA_STOP_K })
+        },
+        reduce,
+        cost,
+    )
+```
+
+- [ ] **Step 6: Give `run_blueprint_member` a `stop` param + the manifest stamp**
+
+In `crates/aura-cli/src/main.rs`, in `fn run_blueprint_member` (line 2877-2886), add a trailing parameter:
+
+```rust
+    topo: &str,
+    env: &project::Env,
+    stop: StopRule,
+) -> RunReport {
+```
+
+Change its `wrap_r` call (line 2892), passing the bound stop:
+
+```rust
+    // before
+    let mut h = wrap_r(signal, tx_eq, tx_ex, tx_r, tx_req, false, true, None)
+    // after
+    let mut h = wrap_r(signal, tx_eq, tx_ex, tx_r, tx_req, StopArm::Bound(stop), true, None)
+```
+
+Stamp the resolved stop into the manifest params — after `let named = zip_params(space, point);` (line 2896):
+
+```rust
+    let named = zip_params(space, point); // by-name params for the manifest record
+    let named = {
+        let mut p = named;
+        // `if let` (not an irrefutable `let`): `StopRule` also has a `Fixed`
+        // variant, which stamps no vol knobs. The campaign/single-run paths only
+        // pass `Vol`, so the `Fixed` arm is inert here.
+        if let StopRule::Vol { length, k } = stop {
+            p.push(("stop_length".to_string(), Scalar::i64(length)));
+            p.push(("stop_k".to_string(), Scalar::f64(k)));
+        }
+        p
+    };
+```
+
+- [ ] **Step 7: Thread the remaining `wrap_r` call sites (bound default)**
+
+In `crates/aura-cli/src/main.rs`, the three other `wrap_r` sites pass `false` as the 6th arg — replace each with `StopArm::Bound(StopRule::Vol { length: R_SMA_STOP_LENGTH, k: R_SMA_STOP_K })`:
+- line 2288: `wrap_r(reload(), tx_eq, tx_ex, tx_r, tx_req, StopArm::Bound(StopRule::Vol { length: R_SMA_STOP_LENGTH, k: R_SMA_STOP_K }), true, None).param_space();`
+- line 2849: `let wrapped = wrap_r(signal, tx_eq, tx_ex, tx_r, tx_req, StopArm::Bound(StopRule::Vol { length: R_SMA_STOP_LENGTH, k: R_SMA_STOP_K }), false, None);`
+- line 2932: `wrap_r(signal, tx_eq, tx_ex, tx_r, tx_req, StopArm::Bound(StopRule::Vol { length: R_SMA_STOP_LENGTH, k: R_SMA_STOP_K }), true, None)`
+
+- [ ] **Step 8: Thread the 5 default `run_blueprint_member` call sites (main.rs)**
+
+In `crates/aura-cli/src/main.rs`, append `StopRule::Vol { length: R_SMA_STOP_LENGTH, k: R_SMA_STOP_K }` as the new last argument at each of these `run_blueprint_member(...)` calls: line 2326 (the `let rerun = run_blueprint_member(` multi-line call — add as the final arg after `env`), 3005, 3038, 3056, 3163. Each was `run_blueprint_member(reload(doc), point, &space, ..., pip, &topo, env)` → `..., &topo, env, StopRule::Vol { length: R_SMA_STOP_LENGTH, k: R_SMA_STOP_K })`.
+
+- [ ] **Step 9: Map the regime → stop in the campaign member runner**
+
+In `crates/aura-cli/src/campaign_run.rs`, in `impl MemberRunner for CliMemberRunner`, `run_member` (line 269-281), map the cell regime and pass it into the `run_blueprint_member` call:
+
+```rust
+    // before the run_blueprint_member call (after the `let signal = ...` at line 269):
+        let stop = match cell.regime {
+            None => aura_composites::StopRule::Vol {
+                length: crate::R_SMA_STOP_LENGTH,
+                k: crate::R_SMA_STOP_K,
+            },
+            Some(aura_research::RiskRegime::Vol { length, k }) => {
+                aura_composites::StopRule::Vol { length, k }
+            }
+        };
+        let mut report = crate::run_blueprint_member(
+            signal,
+            &point,
+            &space,
+            vec![Box::new(source)],
+            (from, to),
+            0,
+            geo.pip_size,
+            &cell.strategy_id,
+            self.env,
+            stop,
+        );
+```
+
+The full paths `aura_composites::StopRule` / `aura_research::RiskRegime` resolve without a new `use` (both crates are aura-cli deps). Also in `crates/aura-cli/src/main.rs`, mark the two stop constants crate-visible so campaign_run.rs can read them:
+
+```rust
+// before
+const R_SMA_STOP_LENGTH: i64 = 3;
+const R_SMA_STOP_K: f64 = 2.0;
+// after
+pub(crate) const R_SMA_STOP_LENGTH: i64 = 3;
+pub(crate) const R_SMA_STOP_K: f64 = 2.0;
+```
+
+- [ ] **Step 10: Build + run the gate (aura-cli, real-data pins)**
+
+Run: `cargo build -p aura-cli 2>&1 | tail -8`
+Expected: `Finished` — 0 errors (all `wrap_r` + `run_blueprint_member` callers threaded).
+Run: `cargo test -p aura-cli --test cli_run sweep_real_blueprint_member_manifest_stamps_the_default_stop 2>&1 | tail -10`
+Expected: PASS (the flipped characterization pin now sees the stamped default stop).
+Run: `cargo test -p aura-cli --test cli_run sweep_real_blueprint_member_lines_pin_the_dissolved_contract 2>&1 | tail -10`
+Expected: PASS (the extended dissolved-contract pin sees the stop keys present).
+Run: `cargo test -p aura-cli 2>&1 | tail -20`
+Expected: PASS across aura-cli. NOTE: the stamp lives in `run_blueprint_member`, so the five single-`blueprint run` paths (main.rs callers at 2326/3005/3038/3056/3163) now stamp the default stop too — the same ratified C18 extension. Any aura-cli test asserting a stop-less blueprint-run OR campaign-member manifest param set is updated here for the additive `stop_length`/`stop_k` keys (an exact-set assertion, not a `find`, is what surfaces it). This is expected drift, not a regression.
+
+---
+
+## Task 5: sugar parity, two-regime E2E, ledger note (aura-cli + docs)
+
+**Files:**
+- Modify: `crates/aura-cli/src/verb_sugar.rs:76`
+- Modify: `crates/aura-cli/tests/research_docs.rs` — the two-regime E2E (its helpers live here)
+- Modify: `docs/design/INDEX.md`
+
+- [ ] **Step 1: Write the failing two-regime E2E**
+
+Add to `crates/aura-cli/tests/research_docs.rs` (its helpers `seed_blueprint` / `SWEEP_ONLY_PROCESS_DOC` / `run_code_in` / `ScratchGuard` live here). The campaign document is written inline (the `campaign_doc_json` helper has no `risk` parameter), carrying a two-regime `risk` section; real-data-gated with the same skip idiom as the sibling e2e:
+
+```rust
+/// Property (risk-regime axis, #210): a campaign document with two vol regimes
+/// runs one sweep family per regime; the families' ids differ by the
+/// `-r{ordinal}` discriminator, and every member's manifest stamps ITS regime's
+/// resolved stop (k=1.5 for regime 0, k=2.5 for regime 1). Gated on the local
+/// GER40 archive.
+#[test]
+fn campaign_two_regimes_stamp_distinct_stops_and_family_ids() {
+    let _fixture = project_lock();
+    let dir = built_project();
+    let runs_dir = dir.join("runs");
+    std::fs::remove_dir_all(&runs_dir).ok();
+    let _cleanup = ScratchGuard(vec![
+        ScratchPath::Dir(runs_dir.clone()),
+        ScratchPath::File(dir.join("regimes.process.json")),
+        ScratchPath::File(dir.join("regimes.campaign.json")),
+    ]);
+    let bp_id = seed_blueprint(dir, "two-regimes-seed");
+    let proc_id = register_process_doc(dir, "regimes.process.json", SWEEP_ONLY_PROCESS_DOC);
+    let doc = format!(
+        r#"{{
+  "format_version": 1,
+  "kind": "campaign",
+  "name": "two-regimes",
+  "data": {{ "instruments": ["GER40"], "windows": [ {{ "from_ms": 1725148800000, "to_ms": 1727740799999 }} ] }},
+  "risk": [ {{ "vol": {{ "length": 3, "k": 1.5 }} }}, {{ "vol": {{ "length": 3, "k": 2.5 }} }} ],
+  "strategies": [ {{ "ref": {{ "content_id": "{bp_id}" }},
+                    "axes": {{ "fast.length": {{ "kind": "I64", "values": [2, 4] }},
+                              "slow.length": {{ "kind": "I64", "values": [8, 16] }} }} }} ],
+  "process": {{ "ref": {{ "content_id": "{proc_id}" }} }},
+  "seed": 7,
+  "presentation": {{ "persist_taps": [], "emit": ["family_table"] }}
+}}"#
+    );
+    write_doc(dir, "regimes.campaign.json", &doc);
+    let (out, code) = run_code_in(dir, &["campaign", "run", "regimes.campaign.json"]);
+
+    if code == Some(1)
+        && (out.contains("no recorded geometry") || out.contains("no data for instrument"))
+    {
+        eprintln!("skip: no local GER40 data for the two-regime campaign e2e");
+        return;
+    }
+    assert_eq!(code, Some(0), "stdout/stderr: {out}");
+
+    // Group member lines by regime discriminator; each stamps its own stop_k.
+    let mut r0_k: Vec<f64> = vec![];
+    let mut r1_k: Vec<f64> = vec![];
+    for line in out.lines().filter(|l| l.starts_with("{\"family_id\":")) {
+        let v: serde_json::Value = serde_json::from_str(line).expect("member line JSON");
+        let fid = v["family_id"].as_str().expect("family_id");
+        let params = v["report"]["manifest"]["params"].as_array().expect("params");
+        let k = params
+            .iter()
+            .find(|p| p[0].as_str() == Some("stop_k"))
+            .and_then(|p| p[1]["F64"].as_f64())
+            .expect("the member manifest stamps stop_k");
+        if fid.contains("-r0-") {
+            r0_k.push(k);
+        } else if fid.contains("-r1-") {
+            r1_k.push(k);
+        }
+    }
+    assert!(!r0_k.is_empty() && !r1_k.is_empty(), "both regime families emitted members: {out}");
+    assert!(r0_k.iter().all(|&k| k == 1.5), "regime 0 stamps k=1.5: {r0_k:?}");
+    assert!(r1_k.iter().all(|&k| k == 2.5), "regime 1 stamps k=2.5: {r1_k:?}");
+}
+```
+
+Run: `cargo test -p aura-cli --test research_docs campaign_two_regimes 2>&1 | tail -20`
+Expected: at RED (before Tasks 3-4 land) this cannot even reach the assertions — but it is authored in Task 5 after Tasks 1-4 are green, so its first run here is the GREEN gate: PASS (or a clean skip on a data-less machine).
+
+- [ ] **Step 2: Add `risk: vec![]` to the generated sweep doc (parity)**
+
+In `crates/aura-cli/src/verb_sugar.rs`, in `translate_sweep`'s `CampaignDoc { ... }` literal (line 76-98), add after the `data: DataSection { ... },` block (line 84):
+
+```rust
+        data: DataSection {
+            instruments: vec![symbol.to_string()],
+            windows: vec![Window { from_ms, to_ms }],
+        },
+        risk: vec![],
+        strategies: vec![StrategyEntry {
+```
+
+- [ ] **Step 3: Verify sugar parity (generated doc unchanged)**
+
+Run: `cargo test -p aura-cli translate_sweep_is_deterministic 2>&1 | tail`
+Expected: PASS — `risk: vec![]` absent-serializes, so the generated campaign doc's content id is byte-unchanged.
+
+- [ ] **Step 4: Add the design-ledger amendment note**
+
+In `docs/design/INDEX.md`, in the C10 (or C20) section, append this paragraph (find the C10 block near line 492 / the C20 structural-axis discussion near line 1622; place it as a dated realization note under whichever the maintainer keeps the structural-axis list):
+
+```markdown
+**Realization (2026-07-06 — the risk regime as a structural campaign axis,
+#210).** The protective-stop regime is a first-class structural axis of the
+campaign document (`CampaignDoc.risk: [RiskRegime]`), a peer of instruments and
+windows — kept-separate in the executor (the nominee key carries the regime
+ordinal), so generalize aggregates across instruments *within* a regime, never
+across regimes. Regimes are compared at presentation, never argmax-selected
+across: a cross-regime E[R] argmax would compare R-multiples in different R units
+(the stop defines 1R), so the verbs' `--stop-length`/`--stop-k` joint stop grid
+is retired as a campaign methodology. Each member manifest stamps its resolved
+stop (default included), closing the C18 gap. Absent `risk` = one implicit
+default regime, absent-serializing for content-id parity.
+```
+
+- [ ] **Step 5: Full workspace gate**
+
+Run: `cargo build --workspace 2>&1 | tail -3`
+Expected: `Finished` — 0 errors.
+Run: `cargo test --workspace 2>&1 | tail -8`
+Expected: PASS across the workspace (the new regime tests green, all prior pins updated).
+Run: `cargo clippy --workspace --all-targets -- -D warnings 2>&1 | tail -3`
+Expected: no warnings.
diff --git a/docs/specs/risk-regime-axis.md b/docs/specs/risk-regime-axis.md
new file mode 100644
index 0000000..f9e4606
--- /dev/null
+++ b/docs/specs/risk-regime-axis.md
@@ -0,0 +1,413 @@
+# Risk regime as a structural campaign axis — Design Spec
+
+**Date:** 2026-07-06
+**Status:** Draft — awaiting user spec review
+**Authors:** orchestrator + Claude
+
+## Goal
+
+The campaign document cannot vary the protective stop. The R-path stop is
+baked to fixed constants (vol-stop length 3, k 2.0) inside the non-serialized
+`wrap_r` scaffolding, invisible to every stored artifact; stored strategy
+blueprints are the signal leg only (price → bias). Only the legacy verbs vary
+stops, and they do it by gridding stop params jointly with the signal params
+and argmaxing across the whole grid — comparing R-multiples measured in
+*different* R units (C10: the stop defines 1R). This blocks the
+behaviour-preserving dissolution of `generalize`, `walkforward`, and `mc`'s
+R-path equally, and leaves the executed stop regime unreconstructable from any
+recorded artifact (the C18 audit gap named in the fork triage).
+
+This cycle makes the risk regime a first-class **structural axis** of the
+campaign matrix — a peer of instruments and windows — so that:
+
+1. a campaign document enumerates a finite list of risk regimes and runs every
+   `(strategy, instrument, window, regime)` cell;
+2. each member's resolved stop is stamped into its manifest, closing the C18
+   gap (the stop becomes addressable, auditable data);
+3. regimes are **compared** at presentation, never argmax-**selected** across —
+   the cross-R-unit comparison the structural framing deliberately forecloses
+   (the parity break ratified in the direction decision, Gitea #210).
+
+The user decision (regime = structural axis, not an ordinary param axis) and
+the derived sub-forks are recorded on Gitea #210 (comments 2846 / 2847). This
+is the design pass that unblocks the remaining verb dissolutions; the
+"how do I find the best regime" methodology is a consequence of the compared-
+not-selected semantics and is deliberately **not** written down (it follows
+from the architecture).
+
+## Architecture
+
+Three tiers, matching the existing campaign stack:
+
+- **Document vocabulary (`aura-research`)** — a new serializable `RiskRegime`
+  closed vocabulary and an optional top-level `CampaignDoc.risk: Vec<RiskRegime>`
+  field. This crate stays dependency-pure (aura-core + serde + sha2); it knows
+  nothing of the runtime `StopRule`.
+- **Matrix expansion (`aura-campaign`)** — the realization matrix gains a
+  fourth structural coordinate. The regime is a **kept-separate** axis (a peer
+  of `window`), not an **aggregated-over** axis (a peer of `instrument`):
+  generalize aggregates across instruments (a candidate must survive *all*
+  instruments — worst-case R floor), but regimes are alternatives compared to
+  find the most robust one, never a set the candidate must all survive. So each
+  `(strategy, window, regime)` triple is an independent generalize-across-
+  instruments unit, and the regime enters the nominee key.
+- **Runtime binding (`aura-cli`)** — the CLI member runner maps
+  `RiskRegime → StopRule` at the runtime boundary (exactly as it maps campaign
+  axes → runtime param-spaces), threads the resolved stop into the `wrap_r`
+  bound-stop arm in place of the baked constants, and stamps the resolved stop
+  into the member manifest.
+
+The **default regime** (absent or empty `risk`) is a single implicit regime
+equal to today's baked constants. The default's *value* lives in `aura-cli`
+(`R_SMA_STOP_LENGTH` / `R_SMA_STOP_K`), so `aura-campaign` carries the regime as
+`Option<RiskRegime>` where `None` means "member runner supplies its default" —
+the doc is never mutated to inject a default (its content id must hash with
+`risk` absent).
+
+## Concrete code shapes
+
+### The campaign document a user writes (the acceptance evidence)
+
+A campaign that sweeps one signal over one instrument/window across **three
+risk regimes** — the new capability:
+
+```json
+{
+  "format_version": 1,
+  "kind": "campaign",
+  "name": "sma-cross across three vol stops",
+  "data": {
+    "instruments": ["GER40"],
+    "windows": [{ "from_ms": 1725148800000, "to_ms": 1727740799999 }]
+  },
+  "risk": [
+    { "vol": { "length": 3, "k": 1.5 } },
+    { "vol": { "length": 3, "k": 2.0 } },
+    { "vol": { "length": 3, "k": 3.0 } }
+  ],
+  "strategies": [
+    { "ref": { "content_id": "<sma-blueprint-hash>" },
+      "axes": { "fast.length": { "kind": "i64", "values": [2, 3] } } }
+  ],
+  "process": { "ref": { "content_id": "<sweep-process-hash>" } },
+  "seed": 0,
+  "presentation": { "persist_taps": [], "emit": ["family_table"] }
+}
+```
+
+Running it produces one family per `(strategy, instrument, window, regime)` —
+three families here, each a sweep over `fast.length ∈ {2,3}` at that regime's
+stop. Every member line carries its resolved stop in the manifest; the three
+regimes' results sit side by side in the family table, compared, never collapsed
+by an argmax. "Best regime" is read off the compared families (the most robust
+out-of-sample R floor across a plateau of stops) — a comparison, not a search.
+
+The **absent-`risk` parity case** — the document the sweep sugar generates and
+every stored campaign document written to date:
+
+```json
+{ "...": "no risk section", "data": { "...": "..." }, "strategies": ["..."] }
+```
+
+runs exactly one regime equal to the baked default (length 3, k 2.0),
+behaviour-identical to today, and its content id is byte-unchanged (the field
+absent-serializes).
+
+### `RiskRegime` — the new closed vocabulary (`aura-research`)
+
+```rust
+/// A protective-stop regime: a serializable, content-addressable mirror of the
+/// runtime `StopRule` structural axis (C10/C20). The sole implemented variant is
+/// the vol-stop; the fixed-stop rule is admitted as a future additive variant
+/// (it ships as a composite today but is not yet campaign-reachable). Tagged so
+/// adding `Fixed` is additive — no content-id churn on stored `Vol` regimes.
+#[derive(Clone, Copy, Debug, PartialEq, Serialize, Deserialize)]
+#[serde(deny_unknown_fields, rename_all = "snake_case")]
+pub enum RiskRegime {
+    Vol { length: i64, k: f64 },
+}
+```
+
+Wire form (serde external tagging): `{ "vol": { "length": 3, "k": 2.0 } }`.
+
+### `CampaignDoc.risk` — the optional top-level field
+
+```rust
+// before → after (crates/aura-research/src/lib.rs:425)
+ pub struct CampaignDoc {
+     pub format_version: u32,
+     pub kind: DocKind,
+     pub name: String,
+     #[serde(default, skip_serializing_if = "Option::is_none")]
+     pub description: Option<String>,
+     pub data: DataSection,
++    /// Structural risk-execution axis: the finite list of stop regimes the
++    /// matrix runs each cell under. Absent or empty = one implicit default
++    /// regime (the runtime baked constants). Absent-serializes → content-id
++    /// parity for every risk-less document.
++    #[serde(default, skip_serializing_if = "Vec::is_empty")]
++    pub risk: Vec<RiskRegime>,
+     pub strategies: Vec<StrategyEntry>,
+     pub process: ProcessRef,
+     pub seed: u64,
+     pub presentation: Presentation,
+ }
+```
+
+`DataSection` is **unchanged** — the regime is a risk-execution concern, kept
+out of the "which instruments over which windows" data section (invariant 7).
+
+### `CellSpec.regime` — the fourth structural coordinate (`aura-campaign`)
+
+```rust
+// before → after (crates/aura-campaign/src/lib.rs:26)
+ pub struct CellSpec {
+     pub strategy_ordinal: usize,
+     pub strategy_id: String,
+     pub blueprint_json: String,
+     pub axes: BTreeMap<String, Axis>,
+     pub instrument: String,
+     pub window_ms: (i64, i64),
++    /// The cell's risk regime. `None` = the member runner's baked default (the
++    /// absent/empty-`risk` case); `Some` = an explicit document regime.
++    pub regime: Option<RiskRegime>,
++    /// The regime's ordinal in the resolved regime list (0 for the default),
++    /// used to key the generalize unit and discriminate family names.
++    pub regime_ordinal: usize,
+ }
+```
+
+### Matrix loop + nominee key (`aura-campaign/src/exec.rs`)
+
+```rust
+// before → after (exec.rs:124 + the strategy×instrument×window loop at :125)
+- let mut nominees: BTreeMap<(usize, usize), Vec<(String, Nominee)>> = BTreeMap::new();
++ let mut nominees: BTreeMap<(usize, usize, usize), Vec<(String, Nominee)>> = BTreeMap::new();
++ // Absent/empty risk resolves to a single default cell (regime = None, ord 0);
++ // a non-empty list maps each regime to Some. The default's value is the member
++ // runner's; the doc is never mutated (content id hashes with risk absent).
++ let regimes: Vec<(usize, Option<RiskRegime>)> = if campaign.risk.is_empty() {
++     vec![(0, None)]
++ } else {
++     campaign.risk.iter().copied().enumerate().map(|(i, r)| (i, Some(r))).collect()
++ };
+  for (strategy_ordinal, ...) in campaign.strategies.iter().zip(strategies).enumerate() {
+      for instrument in &campaign.data.instruments {
+          for (window_ordinal, window) in campaign.data.windows.iter().enumerate() {
++             for (regime_ordinal, regime) in &regimes {
+                  let cell = CellSpec { /* ...as before... */,
++                     regime: *regime, regime_ordinal: *regime_ordinal };
+                  let (outcome, realization) = run_cell(&cell, ...)?;
+                  nominees
+-                     .entry((strategy_ordinal, window_ordinal))
++                     .entry((strategy_ordinal, window_ordinal, *regime_ordinal))
+                      .or_default()
+                      .push((instrument.clone(), outcome.nominee.clone()));
+                  /* ... */
++             }
+          }
+      }
+  }
+```
+
+The campaign-scope generalize loop (exec.rs:164-195) iterates the same
+now-3-tuple key, so each `(strategy, window, regime)` gets its own
+generalize-across-instruments grade. `CampaignGeneralization` gains a
+`regime_ordinal: usize` field beside `strategy_ordinal` / `window_ordinal`.
+
+### Family naming — the regime discriminator (collision fix)
+
+The family name (exec.rs:250 / :352) carries no regime component today, so two
+regimes for the same `(strategy, instrument, window, stage)` would collide and
+overwrite in the registry:
+
+```rust
+// before → after (exec.rs:250, :352)
+- "{campaign_prefix}-{}-{}-w{window_ordinal}-s{stage_ordinal}",
++ "{campaign_prefix}-{}-{}-w{window_ordinal}-r{regime_ordinal}-s{stage_ordinal}",
+```
+
+`campaign_cell_key` (campaign_run.rs:558) gains the regime ordinal by the same
+reasoning (report-name isolation across regimes):
+
+```rust
+// before → after
+- fn campaign_cell_key(strategy: &str, instrument: &str, window_ordinal: usize) -> String
++ fn campaign_cell_key(strategy: &str, instrument: &str, window_ordinal: usize, regime_ordinal: usize) -> String
+```
+
+### `wrap_r` bound-stop arm + the member-runner thread (`aura-cli`)
+
+`wrap_r`'s sixth argument stops being a bare `stop_open: bool` and becomes a
+`StopArm` that carries the bound stop's value:
+
+```rust
+// new CLI-internal enum
+enum StopArm {
+    /// Open vol-stop: the two knobs land in param_space as sweep axes (the r-sma
+    /// verb's gridded-stop path).
+    Open,
+    /// Bound vol-stop with these params (single run, blueprint/campaign member).
+    Bound(StopRule),
+}
+
+// before → after (main.rs:2691 stop arm inside wrap_r)
+- let exec = g.add(if stop_open {
+-     risk_executor_vol_open(1.0)
+- } else {
+-     risk_executor(StopRule::Vol { length: R_SMA_STOP_LENGTH, k: R_SMA_STOP_K }, 1.0)
+- });
++ let exec = g.add(match stop {
++     StopArm::Open => risk_executor_vol_open(1.0),
++     StopArm::Bound(rule) => risk_executor(rule, 1.0),
++ });
+```
+
+The signature change propagates to `wrap_r`'s five call sites (compiler-
+enumerated). `r_sma_graph` (main.rs:2622) keeps its `stop_open: bool` and maps
+at its single `wrap_r` call, localizing the default constants to the Rust-built
+path:
+
+```rust
+// r_sma_graph's wrap_r call
++ if stop_open { StopArm::Open }
++ else { StopArm::Bound(StopRule::Vol { length: R_SMA_STOP_LENGTH, k: R_SMA_STOP_K }) }
+```
+
+`run_blueprint_member` (main.rs:2877) gains a `stop: StopRule` parameter, passes
+`StopArm::Bound(stop)` to `wrap_r`, and stamps the stop into the manifest (next
+shape). `CliMemberRunner::run_member` (campaign_run.rs:215) maps the cell's
+regime to the runtime rule and threads it in:
+
+```rust
+// campaign_run.rs run_member — the RiskRegime → StopRule map at the runtime boundary
++ let stop = match cell.regime {
++     None => StopRule::Vol { length: crate::R_SMA_STOP_LENGTH, k: crate::R_SMA_STOP_K },
++     Some(RiskRegime::Vol { length, k }) => StopRule::Vol { length, k },
++ };
+  let mut report = crate::run_blueprint_member(signal, &point, &space, sources,
+-     (from, to), 0, geo.pip_size, &cell.strategy_id, self.env);
++     (from, to), 0, geo.pip_size, &cell.strategy_id, self.env, stop);
+```
+
+### Manifest stamp — closing the C18 gap (additive, like the instrument stamp)
+
+`run_blueprint_member` builds its manifest from `zip_params(space, point)` —
+the signal axes only (main.rs:2896), so the campaign member manifest records no
+stop today. The resolved stop is appended, matching the single-run manifest
+shape (`stop_length` i64 / `stop_k` f64, main.rs:3608-3609):
+
+```rust
+// before → after (main.rs:2896, inside run_blueprint_member)
+  let named = zip_params(space, point);
++ let named = { let mut p = named;
++     if let StopRule::Vol { length, k } = stop {
++         p.push(("stop_length".into(), Scalar::i64(length)));
++         p.push(("stop_k".into(), Scalar::f64(k)));
++     }
++     p };
+  let mut manifest = sim_optimal_manifest(named, window, seed, pip);
+```
+
+**Ratified contract extension.** `family_member_line` serializes the full
+`RunManifest.params` (main.rs:1601-1606), so this additive stamp changes the
+dissolved-sweep member-line output. That a campaign member manifest carries **no**
+stop param today is a currently-green characterization pin,
+`sweep_real_blueprint_member_manifest_carries_no_stop_param_today`
+(cli_run.rs) — added as this cycle's grounding ratification, since the older
+`sweep_real_blueprint_member_lines_pin_the_dissolved_contract` locates each
+binding by `find` and so never pinned the *absence*. The stamp flips that
+characterization pin to **require** the stop key — the deliberate C18-gap
+closure the milestone exists to perform, an additive stamp exactly like the
+instrument stamp cycle 0110 added ("full parity modulo an additive stamp", #210
+decision 5), not accidental drift. The older `find`-based pin also gains the
+default stop in its member lines (its `find` assertions stay green; it is
+extended to assert the new key). The change is ratified here, not silent.
+
+### `translate_sweep` — sugar parity (no `risk` emitted)
+
+```rust
+// verb_sugar.rs:76 generated CampaignDoc — the risk field defaults to absent
+  CampaignDoc { /* ...unchanged... */, data: DataSection { ... },
++     risk: vec![],   // absent-serializes → sweep-sugar doc byte-unchanged
+      strategies: vec![one], ... }
+```
+
+## Components
+
+- **`aura-research`**: `RiskRegime` enum (new); `CampaignDoc.risk` field;
+  `validate_campaign` regime check (new `DocFault::BadRegime { index, detail }`);
+  `CAMPAIGN_SECTIONS` gains an optional `std::risk` section descriptor;
+  `open_slots_campaign` treats `risk` as optional (never an open slot — absence
+  is legal). `metric_vocabulary` untouched.
+- **`aura-campaign`**: `CellSpec.regime` + `regime_ordinal`; exec.rs regime
+  expansion, 3-tuple nominee key, generalize per `(strategy, window, regime)`;
+  `CampaignGeneralization.regime_ordinal`; family-name regime discriminator.
+- **`aura-cli`**: `StopArm` enum; `wrap_r` signature; `r_sma_graph` bool→arm
+  map; `run_blueprint_member` `stop` param + manifest stamp;
+  `CliMemberRunner::run_member` regime→rule map; `campaign_cell_key` regime arg.
+- **`verb_sugar`**: `translate_sweep` sets `risk: vec![]`.
+- **Design ledger**: a C10/C20 amendment note — the risk regime realized as a
+  structural campaign axis (kept-separate, compared not selected), and the
+  ratified parity break (cross-regime argmax is structurally unavailable; the
+  verbs' `--stop-length`/`--stop-k` joint grid is retired as a methodology).
+
+## Data flow
+
+document (`risk` list) → parse (serde, `risk` known/optional) → `validate_campaign`
+(regime params sane) → content id (risk absent-serializes) → `execute`:
+for each `(strategy, instrument, window, regime)` cell → `run_member` maps
+`regime → StopRule` → `run_blueprint_member` binds the signal point, runs with
+the bound stop, stamps `stop_length`/`stop_k` into the manifest → nominee keyed
+`(strategy, window, regime)` → per-`(strategy, window, regime)` generalize across
+instruments → family table rows carry the regime in `family_id` → presentation
+compares regimes side by side.
+
+## Error handling
+
+- A `Vol` regime with `length < 1` or `k <= 0` (or non-finite `k`) → the new
+  `DocFault::BadRegime { index, detail }` at `validate_campaign`, phrased by the
+  CLI like the sibling `EmptyAxis` / `BadWindow` faults (by-identifier, display-
+  free in the library).
+- `risk: []` (explicit empty) is **valid** — it means the default regime,
+  identical to an absent `risk` (both round-trip to absent under
+  `skip_serializing_if`). No refusal.
+- No duplicate-regime detection, matching the existing non-dedup of instruments
+  and windows (consistency, not a new invariant).
+- An unknown top-level key stays refused by `CampaignDoc`'s
+  `deny_unknown_fields`; `risk` is now a *known* optional key.
+
+## Testing strategy
+
+- **Unit (`aura-research`)**: `RiskRegime` serde round-trip + wire-form pin
+  (`{"vol":{"length":3,"k":2.0}}`); `validate_campaign` accepts a risk section
+  and refuses a bad regime; **content-id parity** — a doc with `risk` absent and
+  the same doc with `risk: []` both hash to the pre-feature content id (the
+  absent-serialize guarantee).
+- **E2E (`aura-cli`)**: a real-data campaign with two distinct regimes runs both
+  families; each member manifest stamps its regime's `stop_length`/`stop_k`; the
+  two families' `family_id`s differ by the `-r{ordinal}` discriminator (no
+  collision/overwrite); the per-`(strategy, window, regime)` generalize grades
+  are independent.
+- **Parity (`aura-cli`)**: the dissolved `aura sweep <blueprint> --real` over an
+  absent-`risk` generated document still runs one default regime; its member
+  lines now additionally carry `stop_length:3`/`stop_k:2.0` — the characterization
+  pin `sweep_real_blueprint_member_manifest_carries_no_stop_param_today` flips
+  from asserting the stop's absence to requiring it, and the `find`-based 0110 pin
+  is extended to assert the new key; the generated doc's content id is unchanged.
+
+## Acceptance criteria
+
+- The intended audience — a researcher authoring a campaign — writes a `risk`
+  list and gets one family per regime, compared side by side (the worked example
+  above is the empirical evidence).
+- Every member manifest records its resolved stop, default included → each run
+  is reproducible from its own manifest (C18); the executed stop is auditable.
+- Regimes are kept separate (per-regime generalize) and compared at
+  presentation; no cross-regime argmax exists (the structural framing forecloses
+  the cross-R-unit comparison — C10).
+- Absent/empty `risk` = byte-identical document content id **and** behaviour
+  parity (one default regime); `aura sweep` sugar emits no `risk`.
+- No new failure class against the core constraints: determinism (the regime is
+  static structural data, bound at bootstrap), causality (unaffected), and the
+  no-look-ahead / one-merge invariants are untouched.