Add trustline-removal preconditions to the ChangeTrust example

[kalepail]

Note

Automated notice: This issue was filed from Stellar Raven's automated evaluation pipeline. Evidence and a public source record are included below. The finding may still be incomplete or incorrect — please verify against the live surface before acting on it.

Finding

The assets skill teaches ChangeTrust(limit: 0) as trustline removal without
the preconditions that make the operation safe and valid. A zero limit can fail
when balance or buying liabilities remain, and an asset trustline referenced by
a liquidity pool cannot be deleted. Open offers commonly create the liabilities
that must be cleared first.

The omission is safety-relevant because a wallet-display entry, claimable
balance, classic asset trustline, and pool-share position require different
actions.

Evidence

Observed 2026-08-04 in the exposed skills.stellar-dev.assets playbook and
checked against:

• https://developers.stellar.org/docs/learn/fundamentals/transactions/list-of-operations
• https://github.com/stellar/stellar-protocol/blob/master/core/cap-0038.md
• https://github.com/stellar/stellar-dev-skill/blob/main/skills/assets/SKILL.md

Additional recorded evidence:

• current skills.stellar-dev.assets removal example says only limit: "10000", // 0 to remove trustline
• current skill best practices omit balance, buying-liability, open-offer, and liquidity-pool-use preconditions
• official operation result documentation defines CHANGE_TRUST_INVALID_LIMIT and CHANGE_TRUST_CANNOT_DELETE
• CAP-0038 defines liquidityPoolUseCount as a deletion constraint for asset trustlines
• 2026-08-05 live primary-source recheck: stellar/stellar-dev-skill main (381ca32) assets SKILL.md still presents limit 0 as removal without balance, liability, offer, or pool-reference preconditions
• 2026-08-05 primary-source check: Stellar XDR and CAP-0038 define CHANGE_TRUST_INVALID_LIMIT for an uncleared balance/liability and CHANGE_TRUST_CANNOT_DELETE for a pool reference

Recommendation

Expand the one removal example just enough to require: identify the asset by
code and issuer; distinguish an actual trustline from display or claimable-
balance state; clear balance and relevant offers/liabilities; exit pool-share
positions or references; then submit ChangeTrust(limit: 0) and surface the
specific result code.

Source Record

This was found by the downstream Raven eval/improvements loop and recorded as sk-013 (skills, discovered 2026-08-04).

Public source record: improvements/skills/sk-013-trustline-removal-omits-safety-preconditions.md

Immutable source snapshot: aaef9b7ad7ba

Resolution Handoff

When a fix is deployed, please link the resolving issue or PR to the source record above and notify Raven through:

https://github.com/stellar-experimental/stellar-raven/issues/new?template=upstream-improvement-ready.yml&title=%5Bupstream-ready%5D%20sk-013%3A%20

Include the finding id, resolving issue/PR, deployed version or timestamp, and the smallest live recheck. Raven independently verifies the upstream surface before changing the finding to fixed-upstream; issue closure or a merged PR alone is not treated as proof. After a distinct reviewer repeats the live check, the active finding is retired to Raven's resolved ledger; a commit-pinned snapshot is preserved when available.

[kaankacar]

🤖 Automated message from Kaan's Automated Triage Bot.

Resolved via #90: the assets skill now has a "Remove Trustline" section covering the four deletion preconditions, with a preflight example and result-code handling. The result-code mappings (op_invalid_limit, op_cannot_delete) were verified against the Horizon and operations references before merging. A small follow-up is landing to correct the manageBuyOffer cancel parameter (buyAmount, not amount) that Copilot's review caught.