Summary

Describe the problem and fix in 2–5 bullets:

• Problem: Telegram model picker dropped long Amazon Bedrock models because callback_data exceeded Telegram's 64-byte limit and those buttons were silently skipped.
• Why it matters: users could not select affected models from /models at all, even though they were configured/allowed.
• What changed: added compact callback fallback format (mdl_sel/{model}), parser support for compact callbacks, and callback-handler provider inference when provider is omitted.
• What did NOT change (scope boundary): no changes to /model directive resolution logic, no catalog/allowlist behavior changes, and no changes outside Telegram model-button callback handling.

Change Type (select all)

• Bug fix
• Feature
• Refactor
• Docs
• Security hardening
• Chore/infra

Scope (select all touched areas)

• Gateway / orchestration
• Skills / tool execution
• Auth / tokens
• Memory / storage
• Integrations
• API / contracts
• UI / DX
• CI/CD / infra

Linked Issue/PR

• Closes Telegram: model buttons silently dropped when Bedrock callback_data exceeds 64 bytes #31815
• Related #

User-visible / Behavior Changes

• Telegram /models inline picker now keeps long model IDs selectable by using a compact callback format when provider/model exceeds Telegram callback limits.
• Compact callbacks are resolved back to full /model <provider>/<model> selections when provider inference is unique.
• Ambiguous compact callbacks now fail safely by returning to provider selection instead of selecting the wrong provider.

Security Impact (required)

• New permissions/capabilities? (No)
• Secrets/tokens handling changed? (No)
• New/changed network calls? (No)
• Command/tool execution surface changed? (No)
• Data access scope changed? (No)
• If any Yes, explain risk + mitigation:

Repro + Verification

Environment

• OS: macOS (Darwin)
• Runtime/container: Node 22 + pnpm
• Model/provider: Amazon Bedrock long model ID (us.anthropic.claude-3-5-sonnet-20240620-v1:0)
• Integration/channel (if any): Telegram
• Relevant config (redacted): agents.defaults.model=bedrock/us.anthropic.claude-3-5-sonnet-20240620-v1:0

Steps

1. On main, build Telegram model buttons for provider amazon-bedrock and model us.anthropic.claude-3-5-sonnet-20240620-v1:0.
2. Observe mdl_sel_amazon-bedrock/us.anthropic.claude-3-5-sonnet-20240620-v1:0 exceeds 64 bytes.
3. Prior behavior: button is skipped (continue), so model is missing/unselectable in Telegram picker.

Expected

• Long model remains selectable in Telegram picker.
• Callback parser/handler supports compact fallback callback data and resolves to the intended provider/model.

Actual

• Long model button is dropped on main, making selection impossible via Telegram picker.

Evidence

Attach at least one:

• Failing test/log before + passing after
• Trace/log snippets
• Screenshot/recording
• Perf numbers (if relevant)

Human Verification (required)

What you personally verified (not just CI), and how:

• Verified scenarios:
  • pnpm test -- src/telegram/model-buttons.test.ts src/telegram/bot.test.ts
  • Added/validated tests for compact callback parsing, compact callback generation, provider inference for compact callbacks, and safe handling of ambiguous compact callbacks.
  • pnpm check passes.
• Edge cases checked:
  • Compact callback with slash-containing model IDs.
  • Ambiguous provider inference for same model ID across providers.
  • Callback byte-length limit enforcement remains <=64 bytes.
• What you did not verify:
  • Live Telegram API interaction in a real chat.

Compatibility / Migration

• Backward compatible? (Yes)
• Config/env changes? (No)
• Migration needed? (No)
• If yes, exact upgrade steps:

Failure Recovery (if this breaks)

• How to disable/revert this change quickly:
  • Revert commit 384410d02.
• Files/config to restore:
  • src/telegram/model-buttons.ts
  • src/telegram/bot-handlers.ts
  • src/telegram/model-buttons.test.ts
  • src/telegram/bot.test.ts
• Known bad symptoms reviewers should watch for:
  • /models inline selection fails to resolve model callback.
  • Compact callback routes to wrong provider instead of showing provider list.

Risks and Mitigations

List only real risks for this PR. Add/remove entries as needed. If none, write None.

• Risk: compact callbacks omit provider and require inference.
  • Mitigation: infer only when exactly one provider matches; otherwise return provider picker with explicit resolution prompt.