feat(agent/agentcontextconfig): fall back to AGENT.md and CLAUDE.md#26282
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feat(agent/agentcontextconfig): fall back to AGENT.md and CLAUDE.md#26282tracyjohnsonux wants to merge 1 commit into
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Coder Agents previously read a single configurable instruction filename (default AGENTS.md). Users coming from other agent tooling expect CLAUDE.md (and to a lesser extent AGENT.md) to work as well. Per directory, the package now searches a comma-separated, priority-ordered list of filenames. The first existing file wins; files that are empty after sanitization fall through to the next candidate, matching Coder's existing empty-file semantics. Default list: AGENTS.md,AGENT.md,CLAUDE.md. The configuration env var is renamed to match the rest of the package (CODER_AGENT_EXP_*_DIRS / *_FILES use the plural form for lists): CODER_AGENT_EXP_INSTRUCTIONS_FILE -> CODER_AGENT_EXP_INSTRUCTIONS_FILES The var is experimental and the rename is a straight swap with no backcompat alias. Setting it to a single name still works and disables the default fallback, which preserves the behavior of users who pinned the old single-name override. Linear: CODAGT-338
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Adds an ordered fallback chain so Coder Agents picks up
AGENTS.md, thenAGENT.md, thenCLAUDE.mdper directory. The first existing file wins; a file that sanitizes to empty falls through to the next candidate, matching Coder's existing empty-file semantics.The configuration env var is renamed to follow the rest of the package convention (
*_DIRS,*_FILESfor comma-separated lists):CODER_AGENT_EXP_INSTRUCTIONS_FILE→CODER_AGENT_EXP_INSTRUCTIONS_FILESThe var is experimental, so the rename is a straight swap with no backcompat alias. Setting it to a single name still works and disables the default fallback, preserving the behavior of any user who pinned the old single-name override.
Refs https://linear.app/codercom/issue/CODAGT-338
Design plan and decision log
Behavior
AGENTS.md,AGENT.md,CLAUDE.mdby default).Env var
One env var, pluralized to match
CODER_AGENT_EXP_INSTRUCTIONS_DIRS,CODER_AGENT_EXP_SKILLS_DIRS, andCODER_AGENT_EXP_MCP_CONFIG_FILES. The closest precedent isCODER_AGENT_EXP_MCP_CONFIG_FILES, which already takes a comma-separated list in dogfood (~/.mcp.json,.mcp.json).Divergences from Mux
Mux already has comparable fallback behavior. We adopt the same priority list but deliberately diverge on two points:
AGENTS.mdfalls through toCLAUDE.md.AGENTS.local.mdfrom the same directory. Not in scope for this change.Scope
agent/agentcontextconfig/api.go— env var rename,Configfield rename, default fallback list,ResolveandContextPartsFromDirparse the list and pass a[]stringof candidate filenames toreadInstructionFileFromDir, which iterates in priority order.agent/agentcontextconfig/api_test.go— six new subtests coveringAGENTS.md > AGENT.md > CLAUDE.mdprecedence, fallback when onlyCLAUDE.mdexists,AGENT.md > CLAUDE.md, emptyAGENTS.mdfalls through, single-name env var disables the default fallback, and per-directory fallback is independent.coderd/x/chatd/chatd_test.go— env var identifier rename only.No downstream changes.
agent/proto,coderd/x/chatd/chatd.go, andcodersdktreat the instruction file as opaque path + content.Authored by Coder Agents on behalf of @tracyjohnsonux.