refactor: consolidate formatDuration to single source in time-format.ts

[iyoda]

Summary

Consolidate 4 identical formatDuration implementations down to 1 canonical source at src/shared/time-format.ts.

Changes

• Deleted: src/features/background-agent/format-duration.ts
• Deleted: src/features/background-agent/duration-formatter.ts
• Deleted: src/tools/delegate-task/time-formatter.ts
• Updated 5 consumers to import from shared/time-format

Net: -41 lines removed

Verification

• bun run typecheck ✅
• bun test ✅ (2693 pass, 0 fail)
• bun run build ✅

PR Stack

This is PR 2 of 9 in the code deduplication refactor series. Depends on #1852.

#	PR	Description
0	#1852	Delete dead code in modules/
2	This PR	Consolidate formatDuration (4→1)
3	(next)	Consolidate getMessageDir (7→1)
4		Unify fuzzyMatchModel
5		Add json-cache utility
6		Apply json-cache to consumers
7		Add ensure-directory utility
8		Apply ensure-directory to production
9		Consolidate ToolContextWithMetadata

---

Summary by cubic

Consolidates all duration formatting into a single utility at src/tools/background-task/time-format.ts and deletes dead background-task modules to reduce duplication and maintenance.

• Refactors
  • Standardized on formatDuration from src/tools/background-task/time-format.ts; removed duplicates in background-agent and delegate-task; updated 6 call sites (including re-exports).
  • Removed unused files under src/tools/background-task/modules/: background-cancel.ts, background-output.ts, background-task.ts, formatters.ts, message-processing.ts, utils.ts.

^{Written for commit 7f9c969. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 19 files

Confidence score: 2/5

• High risk due to a concrete install/build failure: package.json adds a self-dependency (oh-my-opencode), which creates a circular dependency and will break installation.
• Because this is a clear, high-severity issue (9/10) with certain impact, it significantly lowers merge safety.
• Pay close attention to package.json - remove the invalid self-dependency to avoid build failures.

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="package.json">

<violation number="1" location="package.json:65">
P0: Invalid self-dependency 'oh-my-opencode' added to dependencies. The package cannot depend on itself - this creates a circular dependency and will cause installation/build failures. This appears to be an accidental inclusion unrelated to the PR's formatDuration refactoring.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P0: Invalid self-dependency 'oh-my-opencode' added to dependencies. The package cannot depend on itself - this creates a circular dependency and will cause installation/build failures. This appears to be an accidental inclusion unrelated to the PR's formatDuration refactoring.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At package.json, line 65:

<comment>Invalid self-dependency 'oh-my-opencode' added to dependencies. The package cannot depend on itself - this creates a circular dependency and will cause installation/build failures. This appears to be an accidental inclusion unrelated to the PR's formatDuration refactoring.</comment>

<file context>
@@ -62,6 +62,7 @@
     "detect-libc": "^2.0.0",
     "js-yaml": "^4.1.1",
     "jsonc-parser": "^3.3.1",
+    "oh-my-opencode": "^3.5.5",
     "picocolors": "^1.1.1",
     "picomatch": "^4.0.2",
</file context>