Fix occasional assembly mislogging

[SeradedStripes]

Summary of the problem

Editors like Zed Sometimes send "RGBDS Assembly" as the language for .asm files. Since that string isn't in languages.yml or languges_custom.yml, it was stored as is, instead of mapping to Assembly.

Describe your changes

Previously, normalize_direct_heartbeat only fell back to extension detection when the client language was blank or unknown. Now it also falls back whenever the client language isn't recognized.

Comes with 2 tests to verify unrecognized client languages are replaced using extension detection and one to verify recognized languages are still preserved.

Screenshots / Media

N/A

[greptile-apps]

Greptile Summary

This PR changes direct heartbeat normalization so unrecognised client-provided language names fall back to entity-based detection and adds service-level regression coverage.

• Corrects values such as RGBDS Assembly for .asm files.
• Preserves configured client languages during normal direct ingestion.
• Needs to preserve the semantics of resolved last-language placeholders.

Confidence Score: 4/5

The PR should not merge until resolved last-language placeholders are protected from being replaced using the current entity's extension.

The new recognition gate runs after placeholder resolution, so an unrecognised historical language can be replaced with an unrelated extension-derived language and alter both stored metadata and deduplication identity; the added preservation test also cannot detect unconditional fallback.

Files Needing Attention: app/services/heartbeat_ingest.rb, test/services/heartbeat_ingest_test.rb

Important Files Changed

Filename	Overview
app/services/heartbeat_ingest.rb	Adds recognition-gated language inference, but also reinterprets unrecognised values resolved from the last-language placeholder.
test/services/heartbeat_ingest_test.rb	Covers the reported RGBDS case, although the preservation case does not distinguish preservation from extension fallback.

Prompt To Fix All With AI

### Issue 1
app/services/heartbeat_ingest.rb:107-108
**Placeholder language gets overwritten**

When `<<LAST_LANGUAGE>>` resolves to an unrecognised historical value, this check discards that value and infers a language from the current entity instead. For example, after an `RGBDS Assembly` heartbeat, a `.py` heartbeat using the placeholder is stored as Python rather than the requested last language. This also changes the heartbeat identity used for deduplication.

### Issue 2
test/services/heartbeat_ingest_test.rb:839-840
**Preservation test cannot distinguish fallback**

This test uses `language: "Assembly"` with an `.asm` entity, so it still passes if the implementation discards the recognised client language and falls back to extension detection. Use a recognised language that differs from the extension-derived language so the test actually verifies preservation.

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For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "Fall back to extension detection for unr..." | Re-trigger Greptile}

[greptile-apps]

Placeholder language gets overwritten

When <<LAST_LANGUAGE>> resolves to an unrecognised historical value, this check discards that value and infers a language from the current entity instead. For example, after an RGBDS Assembly heartbeat, a .py heartbeat using the placeholder is stored as Python rather than the requested last language. This also changes the heartbeat identity used for deduplication.

Knowledge Base Used: Heartbeat tracking and ingestion

Prompt To Fix With AI

This is a comment left during a code review.
Path: app/services/heartbeat_ingest.rb
Line: 107-108

Comment:
**Placeholder language gets overwritten**

When `<<LAST_LANGUAGE>>` resolves to an unrecognised historical value, this check discards that value and infers a language from the current entity instead. For example, after an `RGBDS Assembly` heartbeat, a `.py` heartbeat using the placeholder is stored as Python rather than the requested last language. This also changes the heartbeat identity used for deduplication.

**Knowledge Base Used:** [Heartbeat tracking and ingestion](https://app.greptile.com/mahadk/-/custom-context/knowledge-base/hackclub/hackatime/-/docs/heartbeat-tracking.md)

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

[greptile-apps]

Preservation test cannot distinguish fallback

This test uses language: "Assembly" with an .asm entity, so it still passes if the implementation discards the recognised client language and falls back to extension detection. Use a recognised language that differs from the extension-derived language so the test actually verifies preservation.

Prompt To Fix With AI

This is a comment left during a code review.
Path: test/services/heartbeat_ingest_test.rb
Line: 839-840

Comment:
**Preservation test cannot distinguish fallback**

This test uses `language: "Assembly"` with an `.asm` entity, so it still passes if the implementation discards the recognised client language and falls back to extension detection. Use a recognised language that differs from the extension-derived language so the test actually verifies preservation.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.