ProvelyNo. Slack Web API returns a success response when it accepts the request. Provely proves posted_to_user and posted as separate promises.
| Fact | Value |
|---|---|
| Skill version | 0.1.0 |
| Publisher | Built and signed by Provely. |
| Certification | Provisional |
| Last conformance run | 2026-09-05T12:00:00Z: 26 of 26 cases passed, 0 critical false VERIFIED |
| Provider API versions | fp_2026_09 |
| Default provider API version | fp_2026_09 |
| Compiled | 2026-09-05 |
| Manifest hash | 79be37dad2c03c4f |
| Manifest hash check | the document hashes to the value the manifest states |
| Signature | valid, key provely-skill-2026-09, trusted by this build |
What does this page prove?
| Claim | Proven by | Evidence | Status |
|---|---|---|---|
| The post event states the channel_type im, so the message reached a direct message conversation and not a public channel. It does not prove which person. | slack.direct_message.posted | E2 + E3 | proven |
| The conversation holds one message with the intended text at the ts that Slack returned. It does not prove that a person read the message. | slack.message.posted | E2 + E3 | proven |
| An outcome outside Slack Web API, such as a bank credit or a person who read a message | not proven | no E5 channel | not proven |
| The agent report that the action worked | never counts | E0 | not proven |
Which completion levels does the Slack Web API skill expose?
Each level is one promise with one contract. An agent picks the level that matches the promise it makes. It cannot upgrade a level. Read the completion level definition.
| Level | Contract | Promise | Evidence | Certification |
|---|---|---|---|---|
posted_to_user | slack.direct_message.posted v1.0.0 | The post event states the channel_type im, so the message reached a direct message conversation and not a public channel. It does not prove which person. | E2 + E3 | Provisional |
posted | slack.message.posted v1.0.0 | The conversation holds one message with the intended text at the ts that Slack returned. It does not prove that a person read the message. | E2 + E3 | Provisional |
Which ways can a Slack Web API action look done and not be?
| Contract | Case | Verdict |
|---|---|---|
| slack.direct_message.posted | duplicate side effect | CONTRADICTED |
| slack.direct_message.posted | pre existing state | CONTRADICTED |
| slack.direct_message.posted | wrong subject | CONTRADICTED |
| slack.message.posted | duplicate side effect | CONTRADICTED |
| slack.message.posted | pre existing state | CONTRADICTED |
| slack.message.posted | wrong subject | CONTRADICTED |
What did the last conformance run show?
The last conformance run on 2026-09-05T12:00:00Z passed 26 of 26 cases with 0 critical false VERIFIED. One critical false VERIFIED rejects a skill.
| Contract | Certification |
|---|---|
slack.direct_message.posted | Provisional |
slack.message.posted | Provisional |
The weakest contract is slack.direct_message.posted. It reaches Provisional. The package level is Provisional, because a package level never rises above its weakest contract. Read the level of the contract you use.
| Case class | Passed | Total |
|---|---|---|
| duplicate side effect | 2 | 2 |
| error after execution | 2 | 2 |
| error before execution | 2 | 2 |
| evidence unavailable | 2 | 2 |
| pre existing state | 2 | 2 |
| stale readback | 2 | 2 |
| still transitional | 2 | 2 |
| terminal success | 2 | 2 |
| timeout after commit | 2 | 2 |
| version mismatch | 2 | 2 |
| webhook duplicate | 2 | 2 |
| webhook out of order | 2 | 2 |
| wrong subject | 2 | 2 |
The conformance artifact digest is 93b0aad442916550. The harness signs the run, so a reader can check that these numbers come from that run.
What remains uncertain?
The level is Provisional because of it. Provely does not guess a rule that a source does not state.
Where do these facts come from?
Every claim above cites a source assertion in the skill provenance. The compiler records the source, its hash, and the retrieval date. A page never states a provider rule without one.
| Source | Kind | Retrieved | Excerpt |
|---|---|---|---|
| slack.docs.conversations | docs | 2026-09-08 | authored |
| slack.docs.events | docs | 2026-09-08 | authored |
| slack.docs.post_message | docs | 2026-09-08 | authored |
| slack.docs.web_api | docs | 2026-09-08 | authored |
| slack.events | event sample | 2026-09-08 | authored |
| slack.openapi | openapi | 2026-09-08 | authored |
How do I verify a Slack Web API action?
Verify a Slack Web API action with Provely
- Begin the operation.Call
beginwith the contractslack.direct_message.postedand the input. Keep the operation id. - Make the Slack Web API call you make today.Send the request with the correlation metadata that
beginreturned. - Submit the acknowledgement.Call
action_resultwith the Slack Web API response. This is evidence level E1. It is not completion. - Verify.Call
verify. The runtime reads the evidence that the contract names, from Slack Web API and not from the agent, and evaluates the contract. - Report the verdict exactly as returned.VERIFIED comes with a signed receipt. PENDING comes with the operation id. CONTRADICTED and UNVERIFIABLE are not success.
Questions developers ask
Does the posted_to_user level prove the posted level?
No. The post event states the channel_type im, so the message reached a direct message conversation and not a public channel. It does not prove which person. The conversation holds one message with the intended text at the ts that Slack returned. It does not prove that a person read the message. Use slack.message.posted to prove posted.
Which Slack Web API API versions does the skill support?
fp_2026_09. An operation on another version returns UNVERIFIABLE with the reason version_unsupported. The runtime never guesses.
Does Provely need write access to Slack Web API?
No. The agent keeps its write key. The verifier reads with a separate read-only credential where Slack Web API permits it, and it never shares that credential with the agent.