docs(#1544): add ADR 0040 for /fs- slash command prefix

[fullsend-ai-coder]

Create ADR 0040 documenting the decision to namespace all fullsend slash commands with the /fs- prefix. This decision was previously captured only as a one-liner in the glossary, causing two separate issues (#1473, #1477) where agents proposed changes that contradicted the undocumented choice.

The ADR records context (multiple AI tools claim bare slash command verbs), the decision (/fs- prefix for all commands), rejected alternatives (bare commands, /fullsend- prefix), and consequences.

Also adds a note to ADR 0002 clarifying that its bare command examples (/triage, /implement, /review) are illustrative and superseded by the /fs- prefix convention.

Note: make lint could not run (Go toolchain download permission denied in sandbox). This is a docs-only change with no Go code affected.

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Closes #1544

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• Tests ran inside sandbox

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Commit: 7b5a89f8fb8adeafbf2359687e8479a496803fa3

[fullsend-ai-review]

Review

Findings

Low

• [docs-currency] docs/glossary.md — The glossary's Slash Command entry references "See ADR 0002 building block 2" but does not mention the new ADR 0042, which is now the authoritative decision record for the /fs- prefix convention. Consider adding a cross-reference to ADR 0042 in the glossary entry.

Info

• [correctness] docs/ADRs/0042-fs-prefix-for-slash-commands.md — Prior review flagged ADR number collision (0040 already existed on main). This has been resolved: the file is correctly renumbered to 0042, and all internal references (title, heading, cross-reference from ADR 0002) are consistent.

Previous run

Review

Findings

High

• [correctness] docs/ADRs/0040-fs-prefix-for-slash-commands.md — ADR number collision. ADR 0040 already exists on main as docs/ADRs/0040-org-pool-for-parallel-e2e-tests.md (merged after this branch was created). ADR 0041 (0041-synchronous-workflow-call-event-dispatch.md) also exists. This PR would create a second file numbered 0040, causing ambiguity in cross-references and the title line (# 40. Use /fs- prefix...). The internal cross-reference from ADR 0002 ([ADR 0040](0040-fs-prefix-for-slash-commands.md)) would also be ambiguous.
  Remediation: Renumber to the next available ADR number (0042). Update the filename, the title in frontmatter and heading, and the cross-reference in docs/ADRs/0002-initial-fullsend-design.md.

Previous run

Review

Findings

High

• [correctness] docs/ADRs/0040-fs-prefix-for-slash-commands.md — ADR number collision. ADR 0040 already exists on main as docs/ADRs/0040-org-pool-for-parallel-e2e-tests.md (merged after this branch was created). ADR 0041 (0041-synchronous-workflow-call-event-dispatch.md) also exists. This PR would create a second file numbered 0040, causing ambiguity in cross-references and the title line (# 40. Use /fs- prefix...). The internal cross-reference from ADR 0002 ([ADR 0040](0040-fs-prefix-for-slash-commands.md)) would also be ambiguous.
  Remediation: Renumber to the next available ADR number (0042). Update the filename, the title in frontmatter and heading, and the cross-reference in docs/ADRs/0002-initial-fullsend-design.md.

Previous run (2)

Review

Findings

No findings.

[fullsend-ai-review]

See the review comment for full details.

[fullsend-ai-review]

[high] correctness

ADR number collision. ADR 0040 already exists on main as docs/ADRs/0040-org-pool-for-parallel-e2e-tests.md (merged after this branch diverged). ADR 0041 also exists. This PR would create a second file numbered 0040, causing ambiguity in cross-references and the title line. The cross-reference from ADR 0002 (ADR 0040) would also be ambiguous.

Suggested fix: Renumber to the next available ADR number (0042). Update the filename, the title in frontmatter and heading, and the cross-reference in docs/ADRs/0002-initial-fullsend-design.md.

[rh-hemartin]

/fs-fix

[fullsend-ai-coder]

🔧 Fix agent — iteration 1 (human-triggered)

Addressed 1 review finding: renumbered ADR 0040 to 0042 to resolve collision with existing ADR 0040 (org-pool-for-parallel-e2e-tests) and ADR 0041 on main.

Fixed (1):

1. ADR number collision — ADR 0040 already exists on main (docs/ADRs/0042-fs-prefix-for-slash-commands.md): Renumbered ADR from 0040 to 0042 (next available number). Updated filename from 0040-fs-prefix-for-slash-commands.md to 0042-fs-prefix-for-slash-commands.md, updated title in frontmatter and heading from 40 to 42, and updated cross-reference in ADR 0002 from ADR 0040 to ADR 0042.

Tests: passed

_{Updated by fullsend fix agent}