docs: rustdoc for receipt-shard's exported names and BuybackConfiguredEvent's fields (#749, #790)

[CHASE3020]

Summary

Doc-comments only. Two rustdoc gaps that an integrating caller hits first — the four exported names of receipt-shard and the five public fields of treasury's BuybackConfiguredEvent — are documented on exactly the lines the two issues own. No signature, body, field, type, order, derive or test change.

missing_docs is not enabled workspace-wide and no CI step runs cargo doc, so both surfaces published with signatures but no contract, no unit, and no statement of who writes a value.

#749 — contracts/receipt-shard/src/lib.rs (4 names)

Line	Item	Added
25	DataKey	role of the key enum (instance state + per-batch records)
70	ReceiptShard	role (one [start_batch_id, end_batch_id) slice of a router's stream) and the router-auth gate on every state-changing call
143	get_batch	read-only/unauthenticated pre-condition; the single Error::BatchNotFound arm and both conditions that produce it (never anchored / already pruned)
186	extend_batch_ttl	publicly callable, no auth; the inactive-shard panic and the Error::BatchNotFound arm

#790 — contracts/treasury/src/buyback.rs (5 fields)

One /// above each named field of BuybackConfiguredEvent:

Line	Field	Added
67	fee_token	domain + writer (set_buyback_config); published as an event topic
69	governance_token	domain + writer; published as an event topic
70	router	domain + writer; carried in the event data
71	burn_address	destination + writer
72	min_amount_in	unit ("fee-token units", the wording the sibling BuybackConfig field already uses) + writer

The struct line itself and every line outside those five is untouched, per the issues' file-ownership regions.

Verification

Toolchain: rustc 1.99.0 / cargo 1.99.0, wasm32v1-none target, rustfmt + clippy components.

Check	Result
cargo fmt --all -- --check	pass (clean, no output)
cargo build --locked --workspace --exclude testutils --target wasm32v1-none --release	pass — same prerequisite CI runs before clippy, because refund-vault/tests/integration_test.rs contractimport!s target/wasm32v1-none/release/receipt_shard.wasm
bash scripts/optimize_wasm.sh	pass — refund_vault.wasm 143330 → 107088 B (under the 131072-byte ledger-entry cap the integration tests upload against)
cargo clippy --locked --all-targets -- -D warnings	pass, exit 0
cargo test --locked --workspace	pass, exit 0 — 44 test binaries, 1088 passed / 0 failed / 0 ignored
cargo doc --no-deps -p receipt-shard -p treasury	pass, exit 0, zero warnings

cargo test --locked --workspace also rewrites contracts/*/test_snapshots/**.json fixtures in-place in a local run (modified files plus a handful of newly written ones under governance/, multisig-account/ and refund-vault/); that churn is not part of this commit — the diff is the four files above.

Fixture that proves each line is handled

A doc comment is only observable through rustdoc, so the artifact is the test: cargo doc -p receipt-shard -p treasury renders every added line into the generated HTML, checked directly in target/doc:

enum.DataKey.html                <- "Storage keys for this shard…"
struct.ReceiptShard.html         <- "A storage shard: holds…"
                                    "Reads this shard's record for `batch_id`…"      (get_batch)
                                    "Extends the TTL of the batch record…"          (extend_batch_ttl)
buyback/struct.BuybackConfiguredEvent.html
                                 <- all five field docs ("Token the treasury spends…",
                                    "Token the treasury buys back and burns…",
                                    "Router the swap is sent to…",
                                    "Destination the bought governance tokens…",
                                    "Smallest swap `execute_buyback` will perform…")

Known limitation (pre-existing, out of these issues' scope)

cargo doc --no-deps --workspace does not build cleanly on current main, and this PR does not change that. With the workspace's warnings = "deny", rustdoc lints fail the build in crates neither issue owns:

• contracts/treasury/src/buyback.rs:12 — rustdoc::redundant_explicit_links ([DexRouter::swap](DexRouter::swap)). This line is module-level and predates the change; the diff here starts at line 65.
• contracts/oracle/src/lib.rs:88, contracts/governance/src/lib.rs:405/792/858 — rustdoc::broken_intra_doc_links.
• contracts/multisig-account (8) and contracts/common (2) — further rustdoc warnings.

Those lines belong to other open issues, so they are left alone. To isolate this change: with just those pre-existing lints allowed, cargo doc --no-deps -p receipt-shard -p treasury completes with zero warnings and exit 0 — i.e. nothing added here introduces a rustdoc warning.

Scope and notes

• Doc comments only: no signature, body, layout, ordering, derive or test change (git diff is additions to comments and nothing else).
• ROADMAP.md gets one checked line per issue, appended; no existing line renumbered or restyled.
• CHANGELOG.md gets a doc-only [Unreleased] entry. This is a pure comments change, so on CONTRIBUTING.md's escape hatch the skip-changelog label would be the alternative — I can't apply it to a PR targeting upstream, so the entry is there to keep the changelog & version check job green. Happy to drop it if a maintainer prefers to label instead.
• missing_docs is deliberately not enabled here — it is a workspace-wide gate with its own owner.

Contract Change Safety Checklist

• Event Shapes: no change — BuybackConfiguredEvent's topics, field names, types and order are untouched (doc comments only), so indexers are unaffected.
• Storage Layout: no change.
• Error Variants: no change; the docs only describe existing arms.
• Changelog: doc-only [Unreleased] entry added (see note above re skip-changelog).
• Deployments: no impact on deployed contracts or DEPLOYMENTS.md.
• Verification: cargo fmt --all -- --check, cargo clippy --locked --all-targets -- -D warnings and cargo test --locked --workspace all pass locally (see table above).

Related Issues

Closes #749
Closes #790

Summary by CodeRabbit

• Documentation
  • Added API documentation for receipt-shard exports and the public fields of the buyback configuration event.
  • Updated the roadmap and changelog to record these documentation changes.

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ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Organization UI
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• Plan: Advanced
• Run ID: 9a5282e3-c3b3-416a-a269-78fc1614e28a

📥 Commits

Reviewing files that changed from the base of the PR and between 8b45443 and 2c03cd2.

📒 Files selected for processing: 2

• CHANGELOG.md
• ROADMAP.md

🚧 Files skipped from review as they are similar to previous changes: 2

• CHANGELOG.md
• ROADMAP.md

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📝 Walkthrough

Rustdoc comments were added for four receipt-shard exports and five public BuybackConfiguredEvent fields. The changelog and roadmap were updated. No signatures, field layouts, or behavior changed.

Changes: Public Rustdoc Updates

Layer / File(s)	Summary
Document receipt-shard exports contracts/receipt-shard/src/lib.rs, ROADMAP.md, CHANGELOG.md	Comments describe DataKey, ReceiptShard, get_batch, and extend_batch_ttl. The roadmap and changelog record the documentation updates.
Document buyback event fields contracts/treasury/src/buyback.rs, ROADMAP.md	Comments describe the configuration source and event publication of the five BuybackConfiguredEvent fields. The roadmap records the update.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~4 minutes

Change: Other

Merge Risk: 🔵 Low · up to 2c03c

The PR is mergeable with a documentation correction: the receipt-shard rustdoc currently overstates the authentication required to extend a batch’s TTL.

Pre-merge checks: 5

Check name	Status	Explanation
Description check		The description includes the required Summary, Contract Change Safety Checklist, Related Issues, and verification details. It clearly explains the documentation-only scope and confirms the checklist i…
Title check		The title is concise and clearly identifies the two documentation changes covered by the pull request, including the affected Rust items and issue numbers.
Linked Issues check		#749 is satisfied by documentation for DataKey, ReceiptShard, get_batch, and extend_batch_ttl, including the reported role, preconditions, authentication, panic, and Error::BatchNotFound beh…
Out of Scope Changes check		The reported source changes are documentation-only and stay on the two issue-owned surfaces. The ROADMAP.md entries are required by the linked issues. The [Unreleased] CHANGELOG.md entry records…
Docstring Coverage		Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 2 files. (2 skipped: 2 …

Full details: Description check

Explanation

The description includes the required Summary, Contract Change Safety Checklist, Related Issues, and verification details. It clearly explains the documentation-only scope and confirms the checklist items.

Full details: Linked Issues check

Explanation

#749 is satisfied by documentation for DataKey, ReceiptShard, get_batch, and extend_batch_ttl, including the reported role, preconditions, authentication, panic, and Error::BatchNotFound behavior. #790 is satisfied by documentation for all five BuybackConfiguredEvent fields, including value domains, units, writers, and event placement where applicable. The reported format, clippy, test, and targeted rustdoc checks pass. The remaining workspace rustdoc warnings are reported in pre-existing, unrelated regions outside both issues' ownership.

Full details: Out of Scope Changes check

Explanation

The reported source changes are documentation-only and stay on the two issue-owned surfaces. The ROADMAP.md entries are required by the linked issues. The [Unreleased] CHANGELOG.md entry records the same documentation change and supports the repository check. No unrelated behavior, tests, signatures, layouts, or event changes are reported.

Full details: Docstring Coverage

Explanation

Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 2 files. (2 skipped: 2 unsupported.)

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Actionable comments posted: 1

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• 🪄 Fix comments: Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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Inline comments:
Review comments at @contracts/receipt-shard/src/lib.rs:
- Line 72: Update the module documentation to limit the router-authentication
claim to batch anchoring and pruning; do not imply that every state-changing
entry point authenticates the router, since extend_batch_ttl does not.

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ℹ️ Review info

⚙️ Run configuration

• Configuration used: Organization UI
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• Run ID: be7e5e3a-e722-4492-b3d6-44f2cd6aa81e

📥 Commits

Reviewing files that changed from the base of the PR and between bb4c341 and 8b45443.

📒 Files selected for processing: 4

• CHANGELOG.md
• ROADMAP.md
• contracts/receipt-shard/src/lib.rs
• contracts/treasury/src/buyback.rs

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MergeKeeper review

Scope: in scope for linked issue #749.
Verdict: clean

The PR successfully adds rustdoc comments to the 4 requested public items in contracts/receipt-shard/src/lib.rs and the 5 requested fields in contracts/treasury/src/buyback.rs, and updates ROADMAP.md and CHANGELOG.md appropriately without modifying code logic or signatures.

Reviewed commit: 2c03cd234e5ce3d4b87d2dccdb9c28401aad55f8.
CI and merge eligibility are checked separately.