feat(governance): derive Mission 70 maturity modulation from XRC price history by jasonz-dfinity · Pull Request #9847 · dfinity/ic

jasonz-dfinity · 2026-04-13T22:27:33Z

Why

Previously, Governance relied on CMC (Cycles Minting Canister) as a middleman for ICP price data used in maturity modulation. This PR cuts out the middleman by having Governance fetch ICP/XDR rates directly from the Exchange Rate Canister (XRC) and derive Mission 70 maturity modulation locally.

https://dfinity.atlassian.net/browse/NNS1-4319

What

IcpPriceHistory: bounded sorted vector of up to 365 daily ICP/XDR rates in Governance state (new proto field 33)
UpdateIcpXdrRateRelatedData: timer task that fetches rates directly from XRC, backfills the last 365 days on first upgrade (~30 min at 5-second intervals), then switches to daily fetches aligned to UTC midnight; recomputes Mission 70 maturity modulation after each update
The existing CMC-polled maturity modulation remains active for spawning/disbursement (switchover is in a later PR)

PR Chain

Testing

Unit tests for the price history buffer, maturity modulation computation, and UTC midnight timer logic.

Copilot

Pull request overview

This PR updates NNS Governance to fetch ICP/XDR rates directly from the Exchange Rate Canister (XRC), persist a bounded daily price history in Governance state, and locally compute Mission 70 maturity modulation from that history.

Changes:

Add a new recurring async timer task (UpdateIcpXdrRateRelatedData) that backfills up to 365 daily rates from XRC and then switches to UTC-midnight-aligned daily updates.
Extend Governance state (proto + heap data) with IcpPriceHistory and MaturityModulation.
Add unit tests covering the rate history buffer behavior, modulation computation, and UTC-midnight delay logic.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
rs/nns/governance/src/timer_tasks/update_icp_xdr_rate_related_data.rs	Implements XRC fetching, price-history maintenance, and maturity modulation computation + scheduling logic.
rs/nns/governance/src/timer_tasks/update_icp_xdr_rate_related_data_tests.rs	Adds unit tests for buffer updates, modulation math, and timer delay behavior.
rs/nns/governance/src/timer_tasks/mod.rs	Wires the new timer task into the governance timer scheduling (wasm32-gated).
rs/nns/governance/src/heap_governance_data.rs	Persists the new proto fields into heap governance state and reassembles them on upgrade.
rs/nns/governance/src/gen/ic_nns_governance.pb.v1.rs	Generated Rust bindings for new proto messages/fields.
rs/nns/governance/proto/ic_nns_governance/pb/v1/governance.proto	Adds `SampledPrice`, `IcpPriceHistory`, and `MaturityModulation` messages + Governance fields (tags 33/34).
rs/nns/governance/Cargo.toml	Adds `ic-xrc-types` dependency.
rs/nns/governance/BUILD.bazel	Adds Bazel dependency on `ic-xrc-types`.
Cargo.lock	Locks the new `ic-xrc-types` dependency.

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github-actions

This pull request changes code owned by the Governance team. Therefore, make sure that
you have considered the following (for Governance-owned code):

Update unreleased_changelog.md (if there are behavior changes, even if they are
non-breaking).
Are there BREAKING changes?
Is a data migration needed?
Security review?

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Select "Dismiss review".
In the text entry box, respond to each of the numbered items in the previous
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$REASON_WHY_NO_NEED. E.g. for unreleased_changelog.md, "No
canister behavior changes.", or for item 2, "Existing APIs
behave as before.".

Brief Guide to "Externally Visible" Changes

"Externally visible behavior change" is very often due to some NEW canister API.

Changes to EXISTING APIs are more likely to be "breaking".

If these changes are breaking, make sure that clients know how to migrate, how to
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If your changes are behind a feature flag, then, do NOT add entrie(s) to
unreleased_changelog.md in this PR! But rather, add entrie(s) later, in the PR
that enables these changes in production.

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GOVERNANCE_CHECKLIST_REMINDER_DEDUP

daniel-wong-dfinity-org · 2026-04-16T09:36:02Z

+}
+
+impl UpdateIcpXdrRateRelatedData {
+    pub fn new_with_client(


Why not just call this new?

daniel-wong-dfinity-org · 2026-04-16T09:36:56Z

+        // Verify that XRC returned a rate for the day we requested. If not, the rate
+        // won't fill the expected slot and backfill would loop on the same day.


Can you ask the FI team in what cases this might happen to confirm that it generally wouldn't?

tmu0 · 2026-04-24T08:30:27Z

+    let previous_permyriad = maturity_modulation.current_value_permyriad.unwrap_or(0) as i64;
+    let previous_day = maturity_modulation.updated_at_days_since_epoch.unwrap_or(0);
+
+    let new_permyriad = compute_maturity_modulation_permyriad(


I would skip this if previous_day == current_day

tmu0 · 2026-04-24T08:31:45Z

+
+#[async_trait]
+impl RecurringAsyncTask for UpdateIcpXdrRateRelatedData {
+    async fn execute(self) -> (Duration, Self) {


Task execution looks brittle. If there is a panic in this method, execution never happens again.

Right, but in the case of a panic, there isn't really a good way of recovering. OTOH, If the instruction limit is hit unintentionally, NOT rescheduling is strictly better. Do you have a suggestion?

tmu0 · 2026-04-24T08:33:47Z

+        }
+
+        // History is complete for current_day: compute maturity modulation.
+        self.governance.with_borrow_mut(|gov| {


dup code, just remove this and return with a short duration

tmu0 · 2026-04-24T08:40:13Z

+            });
+
+            let now = self.governance.with_borrow(|gov| gov.env.now());
+            return (duration_until_next_midnight_utc(now), self);


I don't know if timer scheduling is exact enough that it always hits midnight or later or if in practice this might be already executed short before midnight and in the worst case one day might get skipped. Definitely worth testing and eventually adding a small delta that ensures that we're executing after midnight.

Do you mean if it can be run BEFORE the intended time? I doubt that is possible, but let me confirm.

tmu0 · 2026-04-24T08:42:00Z

+        MIN_MATURITY_MODULATION_PERMYRIAD as i128,
+        MAX_MATURITY_MODULATION_PERMYRIAD as i128,


These are still the old values (-500, 500). What we want is (-1000, 200)

…ract-exchange-rate-client

…e history

…e sum

…name to duration_until_next_midnight_utc

Changelog entry added under Added.
Existing APIs behave as before (additive proto fields only).
New proto fields are additive; no migration needed.
New value computed but not yet consumed by spawning/disbursement (switchover in follow-up PR).

…m-clients (dfinity#9846) ## Why CMC and the upcoming Governance timer task (next PR) both need XRC-calling logic. This extracts the shared code to avoid duplication. https://dfinity.atlassian.net/browse/NNS1-4319 ## What Moved exchange-rate-canister calling logic from CMC into a new shared module in ic-nervous-system-clients: - New exchange_rate_canister_client.rs with ExchangeRateCanisterClient trait, RealExchangeRateCanisterClient, error types, validation helpers, and shared constants - The trait adds timestamp: Option<u64> so callers can request historical rates; CMC always passes None - CMC exchange_rate_canister.rs is updated to use the shared types; its local duplicates are removed This is a pure refactor -- no behavior change to CMC. ### PR Chain - ➡️ Next: dfinity#9847 ## Testing Existing CMC tests cover the refactor.

jasonz-dfinity added the feat label Apr 13, 2026

jasonz-dfinity requested a review from Copilot April 13, 2026 22:30

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Comment thread rs/nns/governance/src/timer_tasks/update_icp_xdr_rate_related_data.rs

Comment thread rs/nns/governance/src/timer_tasks/update_icp_xdr_rate_related_data.rs Outdated

jasonz-dfinity added 3 commits April 15, 2026 11:04

feat: extract shared ExchangeRateCanisterClient into ic-nervous-syste…

6dbfea0

…m-clients

address PR feedback: reflow long doc comment

67e7b8d

address Copilot feedback: fix doc comment and document pow safety

7491aee

jasonz-dfinity force-pushed the jason/NNS1-4319-extract-exchange-rate-client branch from bda03a8 to 7491aee Compare April 15, 2026 19:23

jasonz-dfinity force-pushed the jason/NNS1-4319-compute-maturity-modulation branch from 0724790 to 9a31ba9 Compare April 15, 2026 19:27

fix clippy: separate literal suffix with underscore

76e96e7

jasonz-dfinity force-pushed the jason/NNS1-4319-compute-maturity-modulation branch from 9a31ba9 to a7108f0 Compare April 15, 2026 21:29

jasonz-dfinity marked this pull request as ready for review April 15, 2026 22:32

jasonz-dfinity requested a review from a team as a code owner April 15, 2026 22:32

github-actions Bot previously requested changes Apr 15, 2026

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daniel-wong-dfinity-org approved these changes Apr 16, 2026

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tmu0 reviewed Apr 24, 2026

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jasonz-dfinity added 7 commits April 27, 2026 16:06

Merge remote-tracking branch 'origin/master' into jason/NNS1-4319-ext…

6385037

…ract-exchange-rate-client

address PR feedback: simplify exchange_rate_to_permyriad doc comment

95b28c6

Merge remote-tracking branch 'origin/master' into jason/NNS1-4319-ext…

88c0acd

…ract-exchange-rate-client

feat(governance): derive Mission 70 maturity modulation from XRC pric…

0d97bd6

…e history

address Copilot feedback: validate XRC timestamp, use u128 for averag…

b95c6d0

…e sum

address PR feedback: pass XRC client explicitly to schedule_tasks, re…

005967c

…name to duration_until_next_midnight_utc

fix tests: mock XRC clients must echo requested timestamp

876292a

jasonz-dfinity force-pushed the jason/NNS1-4319-compute-maturity-modulation branch from 1455d28 to 876292a Compare May 5, 2026 23:05

address PR feedback from #9847: rename, dedupe, add Mission 70 bounds

08580a7

Base automatically changed from jason/NNS1-4319-extract-exchange-rate-client to master May 6, 2026 17:22

add changelog entry for Mission 70 maturity modulation timer task

26f160a

jasonz-dfinity requested a review from Copilot May 6, 2026 18:23

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		// Verify that XRC returned a rate for the day we requested. If not, the rate
		// won't fill the expected slot and backfill would loop on the same day.

		MIN_MATURITY_MODULATION_PERMYRIAD as i128,
		MAX_MATURITY_MODULATION_PERMYRIAD as i128,

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jasonz-dfinity commented Apr 13, 2026 •

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